The Sixth Canadian Workshop on Fusarium Head Blight/Le Sixième Colloque canadien sur la fusariose

The Sixth Canadian Workshop on Fusarium Head Blight/Le Sixième Colloque canadien sur la fusariose ^†

Fusarium mycotoxins – biosynthetic pathways and role in virulence. N. J. ALEXANDER, S. P. MCCORMICK AND L. J. HARRIS. Mycotoxin Research Unit, National Center for Agricultural Utilization Research, USDA/ARS, 1815 N. University Street, Peoria, IL 61604, USA; and (L.J.H.) Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Fusarium head blight (FHB) of wheat and barley is a devastating disease that has reached global proportions. Not only does this disease result in lower yields, but the mycotoxins produced by the fungus affect the quality of the grain. Fusarium spp. can produce a number of mycotoxins. The trichothecenes most commonly found in infested grain are deoxynivalenol (DON) and nivalenol (NIV), the former of which has been identified as a virulence factor for FHB. The identification of genes involved in the formation of trichothecenes has lead to the description of a complex biosynthetic pathway. The physical location of the genes involves at least three chromosomes yet expression of many of the toxin biosynthetic genes is coordinated by the products of at least two genes located within the core cluster of 12 genes. The identification of genes involved in the formation of the mycotoxins butenolide and culmorin has been aided by the production of expressed sequence tag (EST) libraries. Searching the libraries for genes expressed at high levels during mycotoxin formation provided a number of candidate genes. Gene knock-out studies, as well as transgenic expression studies, provided the proof of function of these genes. Studies are underway to determine if culmorin and/or butenolide are virulence factors for FHB.

Identification of a biomarker for deoxynivalenol risk assessment and regulation. C. J. AMUZIE AND J. J. PESTKA. Department of Pathobiology and Diagnostic Investigation, and (J.J.P.) Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824, USA

Deoxynivalenol (DON) is the most commonly detected trichothecene fungal metabolite in cereal grains and processed food globally. Upon exposure, DON is rapidly distributed in animal tissues and induces proinflammatory cytokines (< 2 h). Longer term (> 2 weeks) DON exposure reduces weight gain in many species through a less understood mechanism, thus creating uncertainties in human safety assessment. We hypothesized that DON-induced weight reduction is preceded by a dysregulation of growth pathway-related proteins. Models of acute and chronic DON exposure were used to test this hypothesis. We determined that DON acutely induces hepatic suppressors of cytokine signalling (SOCS). The effect of SOCS on growth pathway was evaluated by measuring forms of insulin-like growth factor acid-labile subunit (IGFALS), a growth-related protein. Acute DON exposure (0.1–12.5 mg kg⁻¹) impaired growth hormone-induced IGFALS mRNA by 60–80%. Furthermore, dietary DON (20 ppm for 8 weeks) suppressed IGFALS mRNA (65%), circulating IGFALS (66%), weight gain and elevated plasma DON (≤ 63 ng mL⁻¹). In obese mice, dietary DON (10 ppm) also suppressed circulating IGFALS by 42%. Together, these data indicate that dietary DON consistently suppressed IGFALS in lean and obese mice, while elevating plasma DON. Therefore, circulating IGFALS is a potential biomarker for DON's effect, and might be used for epidemiological surveillance and human risk assessment.

Expression profiling of trichothecene induced genes in wheat. M. BALCERZAK, S. GULDEN AND T. OUELLET. Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Trichothecene mycotoxins synthesized by Fusarium graminearum (Fg) are virulence factors in the infection of plants by Fg. Loss of function mutations of the Fg tri5 gene, the first step in the biosynthesis of trichothecenes, reduced virulence on wheat. However, the effect of DON on the wheat host response to Fg infection is largely unknown. RNA profiling has been performed using the Affymetrix GeneChip Wheat Genome Array, comparing the response of the susceptible wheat cultivar Roblin when inoculated with either a wild type Fg (DON+) strain or a tri5 knockout (DON-) strain. To confirm the microarray expression profiles, quantitative PCR assays were performed on some differentially expressed genes. We identified several DON+ upregulated genes that belong to plant signalling pathways: shikimate, JA, SA and gibberellin pathways. They were designated as basal defence response genes which induction was largely independent of DON accumulation. We also detected several genes that were specifically induced in infection with the DON+ Fg strain, including transcription factors, ubiquitination-related proteins and stress-induced proteins. Some genes, such as cytochrome b561, a leucine-rich repeat protein and shikimate kinase were identified as significantly downregulated in DON+ Fg infection. Our results suggest that wheat response to trichothecene accumulation can be separated from the basal host response to F. graminearum infection.

Effect of glyphosate treatment to previous crop on fusarium head blight in wheat and barley. M. -È. BÉRUBÉ, A. VANASSE, S. RIOUX, N. BOURGET, Y. DION, G. TREMBLAY AND G. BOURGEOIS. Département de phytologie, Faculté des sciences de l'agriculture et de l'alimentation, Pavillon Paul-Comtois, Université Laval, Québec, QC G1V 0A6, Canada; (S.R., N.B.) Centre de recherche sur les grains, 2700, rue Einstein, Québec, QC G1P 3W8, Canada; (Y.D., G.T.) Centre de recherche sur les grains, 740 chemin Trudeau, Saint-Mathieu-de-Beloeil, QC J3G 0E2, Canada; and (G.B.) Horticulture Research and Development Centre, Agriculture and Agri-Food Canada, 430 Gouin Boulevard, Saint-Jean-sur-Richelieu, QC J3B 3E6, Canada

The objective of the study was to determine, under three different tillage practices (conventional, minimum and no-till), the effect of glyphosate applied the year preceding a wheat or barley crop on the incidence of fusarium head blight (FHB). In 2007 and 2008, six field experiments (two species × three tillage practices) were conducted in Saint-Augustin-de-Desmaures and Saint-Mathieu-de-Beloeil, QC. The herbicide treatments, glyphosate (G) and a herbicide (NG) chosen according to weed species were applied as main plots on a RoundUp Ready^TM (RR) soybean. The following year, three wheat and three barley cultivars with different levels of FHB resistance were seeded in their respective experiments as subplots in the main herbicide plots. In 2007, there were no significant herbicide × cultivar interactions nor herbicide effects on visual symptoms, DON content and amount of inoculum of Fusarium graminearum (Fg) coming from soybean residues. In 2008, only the barley-minimum-till trial of Saint-Augustin showed a DON content significantly (P = 0.046) higher in G (1.5 ppm) than in NG (1.1 ppm) treatments, but there was no significant herbicide effect on Fg inoculum production. All results collected indicate that under Quebec cropping conditions, glyphosate used on a RR soybean as previous crop has no or low impact on FHB whatever the tillage practices used.

Realistic expectations of foliar fungicides for management of fusarium head blight. L. BOURGEOIS AND S. HENRY. Bayer CropScience, 430-B Dovercourt Drive, Winnipeg, MB R3Y 1N4, Canada

The performance of fungicide to manage fusarium head blight (FHB) can be affected by fungicide type, crop variety, application quality and application timing. Current fungicide options for FHB management are limited to the triazole family and provide disease suppression averaging 25% for Folicur and 40% for Proline. The second factor is related to the responses to varieties to fungicides/disease interaction. The susceptibility of varieties amongst cultivar is well documented but more research is needed in evaluating the interaction of the fungicides and the cultivars. Finally application quality and timing are essential for optimum performance of the fungicides. Coverage peaks at about 30% using the best spray technology available. Application timing is fleeting with drop of efficacy of fungicides prior to and after the optimum timing. Therefore fungicides require to be integrated with other FHB management tools in order to produce a quality crop with low Fusarium damage.

Genetics of fusarium head blight resistance in wheat. H. BUERSTMAYR, T. BAN, J. A. ANDERSON, M. BUERSTMAYR, K. HUBER, A. ALIMARI, B. STEINER AND M. LEMMENS. University of Natural Resources and Applied Life Sciences Vienna, Department IFA-Tulln, Konrad Lorenz Str. 20, A-3430 Tulln, Austria; (T.B.) Kihara Institute for Biological Research, Yokohama City University, 641-12 Maioka-cho, Totsuka-ku, Yokohama 244-0813, Japan; and (J.A.A.) Department of Agronomy and Plant Genetics, University of Minnesota, 411 Borlaug Hall, 1991 Buford Cir., St. Paul, MN 55108, USA

In the wheat gene pool significant variation for resistance to fusarium head blight is evident. Resistance to fusarium head blight is a quantitative trait controlled by polygenes. During the past decade numerous studies have been performed to decipher the inheritance of fusarium head blight resistance in wheat. We summarize the relevant findings from 51 quantitative trait loci (QTL) mapping studies, nine research articles on marker assisted selection and seven on marker-assisted germplasm evaluation. QTL for FHB resistance were reported on all wheat chromosomes except 7D. Some QTL were found in several independent mapping studies indicating that such QTL are stable and appear therefore useful in breeding programmes. We summarize and update current knowledge on the genetics of fusarium head blight resistance in wheat and review breeding strategies based on the available information and DNA markers. A detailed review on FHB resistance QTL has been published recently by Buerstmayr et al. (2009) Plant Breed., 128, 1–26. In addition some information on ongoing research work at the group of IFA-Tulln will be presented, especially on mapping novel FHB resistance from Triticum macha, T. dicoccum and T. dicoccoides, as well an ongoing work on the identification of candidate FHB resistance genes based on differential gene expression experiments.

Effectiveness of marker-assisted selection for resistance to fusarium head blight in a wheat backcross breeding program. W. CAO, G. FEDAK, D. SOMERS, C. MCCARTNEY, A. XUE, M. E. SAVARD AND H. VOLDENG. Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada (AAFC), Ottawa, ON K1A 0C6, Canada; (D.S., C.M.) Cereal Research Center, AAFC, 195 Dafoe Road, Winnipeg, MB R3T 2M9, Canada

The objective of this study was to determine the effectiveness of marker-assisted selection (MAS) relative to conventional visual selection (CVS) for resistance to FHB in a spring wheat backcross breeding programme. BW301, an elite line but susceptible to FHB, was crossed with HC374, a line resistant to FHB and carrying three QTLs, and the F₁ backcrossed to BW301. A MAS population (MAS BC₂F₅) has been developed through an F₂-derived method, while two conventional visual selection populations (CVS BC₁F₆ and BC₂F₅) have been developed through single seed descent. A combined analysis showed that the means for FHB incidence, severity and FHB index and deoxynivalenol (DON) content for the MAS population were 39.2%, 27.3%, 11.2% and 4.6 ppm. For the CVS BC₁population these values were 43.0%, 30.8%, 14.4% and 6.1 ppm, and for the CVS BC₂ population they were 50.6%, 41.2%, 21.6% and 9.1 ppm. Marker profiles showed that the lines in the CVS BC₁ population carried from 0 to 2 QTLs whereas none of the lines in CVS BC₂population carried the FHB resistance QTLs. The results confirmed that MAS is more effective than CVS for improving FHB resistance in wheat backcross breeding programmes. The results also suggested that minor genes have an important role in providing resistance to FHB of wheat.

Application of marker-assisted selection for development of white seeded wheat resistant to fusarium head blight. W. CAO, G. FEDAK, D. SOMERS, H. VOLDENG, A. XUE, M. SAVARD AND S. MILLER. Eastern Cereals and Oilseeds Research Centre, Agriculture and Agri-Food Canada (AAFC), Central Experimental Farm, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; (D.S.) Cereal Research Centre, AAFC, 195 Dafoe Road, Winnipeg MN R3T 2M9, Canada

We are attempting to develop a white-seeded wheat with a high level of fusarium head blight (FHB) resistance using marker-assisted selection (MAS). ‘Snowbird’, a FHB susceptible white hard-seeded wheat registered by the C. R. C. in Winnipeg, was crossed to ‘Sumai 3’, a FHB resistant wheat, as a female parent. Twenty thousand F₂ plants were produced and grown in the greenhouse. One thousand and five hundred white seeds were visually selected and advanced to F₅ by single seed descent. At the seedling stage of F5, a MAS was performed for three FHB QTLs on chromosome 5A, 3B and 6B. Two hundred and fifty F₅ lines were selected with two or three resistance QTLs and grown in a FHB nursery in 2008. Fifteen F₆ lines were selected based on FHB resistance and agronomic performance. These 15 lines, parents ‘Sumai 3’ and ‘Snowbird’, plus ‘AC Vista’ as a check were planted in the FHB nursery with three replications and in a preliminary yield trial with two reps in the summer of 2009. The results showed that several white seeded wheat lines had high levels of resistance to FHB; significantly higher than ‘Snowbird’ and matured earlier than ‘Sumai 3’. Quality is also improved significantly compared to ‘Sumai 3’, based on the Glutomatic test.

Differential gene expression of wheat backcross lines with Fusarium resistance QTL. W. CHEN AND P. SCHWEIZER. Leibniz Institute of Plant Genetics and Crop Plant, Corrensstrasse 3, 06466 Gatersleben, Germany

Fusarium head blight (FHB) is a devastating disease of several species of wheat and other cereals. Resistance to FHB is governed by quantitative trait loci (QTL) distributed on different chromosomes, but the genes at these QTL and their function in resistance are still unknown. Winter wheat backcross lines carrying two resistance QTLs (on chromosomes 3BS and 5A) against FHB were used to investigate QTL-specific differential gene expression between resistant and susceptible lines following single spikelet inoculation with Fusarium culmorum spores. Transcript profiling was carried out by using a barley 13K cDNA macroarray, which contains EST clones from different pathogen-attacked tissues. By analyzing differential gene expression from 72 hybridization experiments, seven candidate genes were found to be significantly upregulated at 48 h after inoculation in a resistant line pool carrying both 3BS and 5A QTL, but not in a susceptible line pool, in which both QTL were absent. A functional test system based on virus-induced gene silencing (VIGS) in adult wheat plant was established and ready for testing the function of those seven candidate genes.

Efficacy of ACM941-CU, a formulated product of Clonostachys rosea strain ACM941 on the control of fusarium head blight in wheat. Y. H. CHEN AND A. G. XUE. Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Previous studies demonstrated that Clonostachys rosea (Link:Fr.) Schroers strain ACM941 was an antagonist against Gibberella zeae (Schw.) Petch, the causal agent of fusarium head blight (FHB) of wheat in Canada. This research was to evaluate the efficacy of ACM941-CU, a formulated product of ACM941, on the reduction of perithecial production and control of FHB in comparison with registered fungicide Folicur^® (tebuconazole). Over the average of two field trials in 2009, ACM941-CU reduced the daily perithecial reproduction over a period of 42 days by 90% on corn residues, 90% on soybean residues and 71% on wheat residues. These effects were better than those of tebuconazole in the same trials. Five concentrations of ACM941-CU, ranging from 10⁴ to 10⁸ CFU mL⁻¹, were tested for the control of FHB in 2009 and ACM941-CU at 10⁸ CFU mL⁻¹ was the most effective treatment, reducing the area under the disease progress curve (AUDPC) by 79%, infected spikelets (IS) by 30% and Fusarium-damaged kernels (FDK) by 91% in the greenhouse experiments. Under field conditions, ACM941-CU significantly reduced the AUDPC by 43%, FHB index by 52%, IS by 45% and FDK by 43%. These effects were less but not significantly different from those achieved with tebuconazole, suggesting that ACM941-CU is a promising biocontrol product and may be used for managing FHB in wheat.

Impact of fusarium head blight on grain grading and handling in Canada. R. CLEAR AND T. NOWICKI. Grain Research Laboratory, Canadian Grain Commission, 1404-303 Main Street, Winnipeg, MB R3C 3G8, Canada

Since fusarium head blight first became a Canadian issue in 1980, it has influenced the grading and handling of cereals. With increasing research and practical experience we have been able to relax the initially very tight tolerances while improving grower returns and marketability, and meeting ever more stringent and numerous government regulations. Handling of infected grain has run the gamut from an early outright ban on exports, to the present system where blending, advanced cleaning equipment, and regular monitoring manages the quality and safety of our exports. The development of rapid toxin testing methods has given another tool to the industry, and is often employed in the selection of grain for DON-sensitive industries such as malt production and livestock feed. While the grain industry has developed ways of handling infected grain, producers have had less success reducing disease levels. Development of improved varieties has been slow, and better management practices have limited effect. In the worst affected areas, entire classes of grain have essentially been lost to producers. In the first 20 years the area affected by Fusarium graminearum Schwabe grew steadily, mainly in the eastern prairies. The recent change in the pathogen population may result in increasing toxin levels in the grain, which in turn might require lowering grading tolerances.

Results of field inoculation of barley lines by two chemotypes of Fusarium graminearum . R. CLEAR, J. TUCKER, D. GABA, S. PATRICK AND B. LEGGE. Grain Research Laboratory, Canadian Grain Commission, 1404-303 Main Street, Winnipeg, MB R3C 3G8, Canada; (J.T., B.L.) Brandon Research Centre, Agriculture and Agri-Food Canada, P.O. Box 1000A, R.R. 3, Brandon, MB R7A 5Y3, Canada

In 2008, autoclaved corn kernels colonized by Fusarium graminearum Schwabe were spread between lines of barley in a fusarium head blight (FHB) nursery at a 2:1 ratio of 15-acetyldeoxynivalenol (15ADON) to 3ADON isolates. This was the first use in this field of a 3ADON isolate after nine years of artificial inoculation with exclusively 15ADON isolates. Fusarium graminearum infected an average of 88.5% of 1800 seeds tested, with little difference across the nursery. However, the chemotype distribution of F. graminearum recovered from infected kernels, and DON levels, showed a several fold difference from the eastern (67% 3ADON isolates and 46 ppm) to the western end of the field (16% 3ADON isolates and 13 ppm). Highest DON and 3ADON levels were associated with the highest frequency of the 3ADON chemotype, but not without exception. The difference in results between the eastern and western end of the nursery suggests that resident inoculum on previous crop residue played an important role in the disease. Although the 3ADON isolates were recovered from 44% of the infected grain, significantly higher than the expected recovery rate, the possible impact of resident inoculum makes it difficult to draw firm conclusions at this time regarding differences in competitive ability between the two chemotypes.

Systemic germplasm development delivers more fusarium head blight resistance together with maximum test weight in bread wheat. A. COMEAU, F. LANGEVIN, Y. DION, S. RIOUX AND H. VOLDENG. Soils and Crops Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 2560 Hochelaga Boulevard, Québec, QC G1V 2J3, Canada; (Y.D.) Centre de recherché sur les grains (CÉROM), 740, chemin Trudeau, Saint-Mathieu-de-Beloeil, QC J3G 2E0. Canada; (S.R.) CÉROM, Complex scientifique, 2700 rue Einstein, Québec, QC G1P 3W8, Canada; and (H.V.) Eastern Cereal and Oilseed Research Centre, AAFC, 960 Carling Avenue, Ottawa,ON K1A 0C6, Canada

In breeding trials in Eastern Canada, a test weight (TWT) (syn. specific weight) above 82 kg hL⁻¹ is seldom obtained. Going back from 2003 to 2008, in most years, less than 1% of the TWT data of individual registration candidate lines at any given yield trial site went above 82. In 2009, in artificially inoculated fusarium head blight (FHB) resistance trials in Lévis, ‘SS Blomidon’ had a TWT near 73; bread-making check cultivars had TWT values near 74–76, and yet many progenies of the systemic selections from the cross AB143 had a TWT above 83. This cross had been selected annually (from F₁ to F₇) for multiple disease and stress resistance, including very high FHB resistance, through a systemic methodology. High TWT is not totally equivalent to FHB resistance; grain shape and composition also alter TWT, and any stress during grain fill also reduces it. However, although so many factors can reduce TWT, whenever FHB plays a role, maximal values above 83 can be attained only if the resistance-tolerance factors include very high FHB resistance. Selection for TWT is not costly. This trait is very important for the wheat industry. A stringent use of TWT selection can be recommended to increase FHB resistance and also obtain stable cultivar performance.

Transgenic field trials for fusarium head blight resistance and related research in wheat and barley. L. DAHLEEN, R. DILL-MACKY, J. SHAH, G. MUEHLBAUER, R. SKADSEN, M. MANOHARAN, T. ABEBE AND J. JURGENSON. USDA-Agricultural Research Service, 1307 18^th Street N. Fargo, ND 58105, USA; (R.D-M.) Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108, USA; (J.S.) Department of Biological Sciences, University of North Texas, Denton, TX 76203-5220, USA; (G.M.) Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN 55108, USA; (R.S.) USDA-ARS, Cereal Crops Research Unit, 205 Walnut Street, Madison, WI 53726, USA; (M.M.) Department of Agriculture, University of Arkansas Pine Bluff, AR 71601, USA; and (T.A., J.J.) Department of Biological Sciences, University of Northern Iowa, Cedar Falls, IA 50614, USA

Transgenic wheat and barley lines expressing genes with the potential to reduce fusarium head blight (FHB) and deoxynivalenol (DON) have been tested in field trials in MN since 1997 and in ND since 2001 (barley only). Replicated trials are planted, grown and harvested to meet containment regulations of the Animal and Plant Health Inspection Service (APHIS) to prevent accidental escape of the transgenic organisms, and trials are routinely inspected. Harvested seed is evaluated for DON contamination in laboratories at MN and ND. Early transgenes used were typically genes for antifungal compounds or genes induced by pathogen infection. More recently, genes selected as specifically influencing FHB reaction in model systems have been inserted into wheat and barley. As homozygous lines are developed, they are tested in these field trials, providing direct comparisons with resistant and susceptible lines from wheat and barley breeding programmes.

Developing a yipee wheat cultivar. R. M. DEPAUW AND R. E. KNOX. Semi-Arid Prairie Agricultural Research Centre, Agriculture and Agri-Food Canada, P.O. Box 1030, Swift Current, SK S9H 3X2, Canada

Recombining multi-genes that confer resistance to fusarium head blight (FHB) (caused by Fusarium spp.) with the myriad of genes for ‘on-farm’ production traits, resistance to rusts and smuts, and high grain yield of premium end-use suitability has been a major challenge. Carberry represents a ‘step change’ in variety development in the Canada Western Red Spring market class. Carberry sets a new standard for resistance to FHB coupled with high grain yield, high protein concentration, semidwarf stature with strong straw, and resistance to leaf rust, stem rust and common bunt. Based on 36 trials over three years, Carberry yielded similar to ‘Superb’, the highest yielding check. Carberry had protein concentration 0.5 units higher than Superb. These attributes were achieved without extending maturity beyond that of ‘Superb’, the latest maturing check. Carberry had significantly shorter straw than the semidwarf ‘Superb’, and had significantly higher volume weight than ‘Superb’. Carberry derives from parents ‘Alsen’ and ‘Superb’. Access to FHB disease nurseries to phenotype large populations has been fundamental to shift the frequency of desirable gene combinations, to identify superior recombinants and to overcome negative associations. Doubled haploid technology accelerated production of inbred lines to be assessed against the battery of target trait requirements in the development of Carberry.

Investigating the role of the production of indole-3-acetic acid in Fusarium graminearum . C. DESROCHES, T. OUELLET AND M. BALCERZAK. Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON, Canada K1A 0C6, Canada

The auxin, indole-3-acetic acid (IAA), is well known as a key plant hormone regulating multiple facets of development in various cell types, including cell division, elongation and differentiation. The production of IAA is however not limited to plants, some bacteria and fungi are also able to synthesize this hormone but its role is not as well defined, ranging from pathogenesis to phytostimulation. In recent years, many studies have focused on the role of the production of IAA during infection, suggesting that some pathogens may synthesize IAA or manipulate plant auxin biosynthesis to promote virulence and disease. In contrast to the broad insight of IAA biosynthesis pathways in plants and bacteria, little is known about IAA biosynthesis in fungi. The ability of Fusarium graminearum Schwabe to efficiently convert exogenously added tryptophan to IAA and the subsequent large accumulation of IAA levels upon infection suggests a potential role for pathogen-induced IAA as an infection strategy for this pathogen. These initial results are leading to further research in order to investigate this prediction.

Intracellular expression of a single-domain antibody reduces cytotoxicity of 15-AcDON. P. J. DOYLE, H. SAEED, A. HERMANS, S. C. GLEDDIE, G. HUSSACK, M. E. SAVARD, B. A. BLACKWELL, C. SEGUIN, C. R. MACKENZIE AND J. C. HALL. Department of Environmental Biology, University of Guelph, Guelph, ON N1G 2W1, Canada; (H.S., A.H., S.C.G., M.E.S., B.A.B., C.S.) Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, Ottawa, ON K1A 0C6, Canada; and (C.R.M.) Institute for Biological Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada

15-acetyl-deoxynivalenol (15-AcDON) is a low molecular weight sesquiterpenoid trichothecene mycotoxin associated with fusarium ear rot of maize and fusarium head blight of small grain cereals. The accumulation of mycotoxins such as 15-AcDON and deoxynivalenol (DON) within harvested grain is subject to stringent regulation as both toxins pose dietary health risks to humans and animals. These toxins inhibit peptidyl transferase activity which in turn limits eukaryotic protein synthesis. To assess the ability of intracellular antibodies (intrabodies) to modulate mycotoxin-specific cytotoxocity, a gene encoding a camelid single-domain antibody fragment (V_HH) with specificity and affinity for 15-AcDON was expressed in the methylotropic yeast Pichia pastoris (Guilliermond) Phaff. Mycotoxin-mediated cytotoxicity was assessed by continuous measurement of cellular growth. At equivalent doses, 15-AcDON was significantly more toxic to wild-type P. pastoris than was DON which, in turn, was more toxic than 3-AcDON. Intracellular expression of toxin-specific V_HH within P. pastoris conveyed significant (P = 0.01) resistance to 15-AcDON cytotoxicity at doses ranging from 20 to 100 μg mL⁻¹. Interestingly, we documented a biochemical transformation of DON to 15-AcDON which explained significant attenuation to DON at 100 and 200 μg mL⁻¹. The ‘proof of concept’ established in this work suggests that in plants V_HH expression may lead to enhanced tolerance to mycotoxins and limit Fusarium infection of commercial agricultural crops.

Approaches to improving the fusarium head blight resistance of triticale. G. FEDAK, W. CAO, J. GILBERT, A. XUE, A. COMEAU, F. EUDES AND A. SINGH. Eastern Cereals and Oilseeds Research Centre, Agriculture and Agri-Food Canada (AAFC), 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; (J.G.) Cereal Research Centre, AAFC, 195 Dafoe Road, Winnipeg, MB R3T 2M9, Canada; (A.C.) Soils and Crops Research and Development Centre, AAFC, 2560 Hochelaga Boulevard, Quebec, QC G1V 2J3, Canada; (F.E.) Lethbridge Research Centre, AAFC, P.O. Box 3000, Lethbridge, AB T1J 4B1, Canada; and (A.S.) Semiarid Prairie Agricultural Research Centre, AAFC, P.O. Box 1030, Swift Current, SK S9H 3X2, Canada

A screening of genebank accessions has identified TMP 16315 with a good level of resistance to Type I, Type II and Type III. This accession has been crossed to ‘AC Ultima’ and the production of a mapping population by means of microspore culture is in progress. A second approach is to produce new combinations of primary triticale using fusarium head blight (FHB)-resistant Brazilian rye landraces such as Boller and Vacaria. These have been crossed onto Canadian durum cultivars such as ‘Strongfield’ and ‘Brigade’ and the amphiploids have been produced. Another approach is to enhance the FHB resistance of durum wheat as a prerequisite to the production of new combinations of primary triticale. Firstly, after extensive screening, a strain of Triticum carthlicum (4×) with good type II resistance was identified. Resistance quantitative trait loci (QTL) were mapped on chromosome 6B, while a QTL for resistance in ‘Strongfield’ was mapped to chromosome 2B. This same population was used to map a QTL for Type I resistance on chromosome 5A. An attempt was made to introgress the FHB resistance QTL of ‘Sumai3’ into ‘Strongfield’ durum. Preliminary observations indicate that a few durum lines from this combination have enhanced levels of FHB resistance. Finally a durum line with enhanced FHB resistance was isolated from hybrids with tritordeum (AABBHH).

Two new sources of fusarium head blight resistance in bread wheat. G. FEDAK, W. CAO, J. GILBERT, A. XUE, M. SAVARD AND H. VOLDENG. Eastern Cereals and Oilseeds Research Centre, Agriculture and Agri-Food Canada (AAFC), 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; and (J.G.) Cereal Research Centre, AAFC, 195 Dafoe Road, Winnipeg, MB R3T 2M9, Canada

Two bread wheat lines have been produced with resistance from two different wild wheat species. The resistance of M321 is derived from Triticum monococcum L., while the resistance of S184 is inherited from Aegilops speltoides Tausch. Both have an ‘AC Superb’ genetic background. Some of the linkage drag that was present in segregating progenies included late maturity, excessive plant height and other undesirable agronomic traits. As a result of selection against these factors, these two lines have minimal linkage drag. For example, in terms of grain yield, days to heading, test weight and thousand kernel weight the two lines are very similar to ‘AC Barrie’, the check cultivar. The protein content of the two lines was nearly identical to that of ‘AC Barrie’. The grain samples of ‘AC Barrie’ gave a flour yield of 66.8%, S184 gave 67.2% and M321 gave 57.5%. In the latest test M321 and S184 had DON contents of 1.6 and 0.7 ppm, respectively, compared with ‘AC Barrie’ at 4.5 and ‘Roblin’ at 10.4 ppm. Molecular markers, to facilitate the pyramiding of these sources of resistance with other known sources, are being developed. Thus far a unique quantitative trait locus for resistance has been mapped on chromosome 5A of M321.

Glyphosate associations with Fusarium diseases of cereal and pulse crops. M. R. FERNANDEZ, R. P. ZENTNER, P. BASNYAT, D. GEHL, F. SELLES, D. HUBE AND R. J. KREMER. Semiarid Prairie Agricultural Research Centre, Agriculture and Agri-Food Canada (AAFC), P.O. Box 1030, Swift Current, SK S9H 3X2, Canada; (D.G.) Indian Head Research Farm, AAFC, P.O. Box 760, Indian Head, SK S0G 2K0, Canada; (F.S.) Brandon Research Centre, AAFC, P.O. Box 1000A, Brandon, MB R7A 5Y3, Canada; (D.H.) Purdue University, Botany and Plant Pathology Department, 915 West State Street, West Lafayette, IN 47907-2054 USA; and (R.K.) USDA, ARS, 302 ABNR Building, University of Missouri, Columbia, MO 65211 USA

A summary of multi-year field studies on the effects of tillage systems and glyphosate use on the development of fusarium head blight (FHB) and common root rot (CRR) in wheat and barley in eastern Saskatchewan will be presented. Although environment was the most important factor determining FHB development, previous glyphosate use and tillage practice were among the production factors with the greatest association with FHB. Overall, disease was highest in crops under minimum-till management. Previous glyphosate use was consistently associated with higher FHB levels caused by Fusarium avenaceum (Fr.) Sacc. and Fusarium graminearum Schwabe. Cochliobolus sativus (Ito & Kurib.) Drechs.:Dastur, the most common CRR pathogen, was negatively associated with previous glyphosate use, while other fungi, including F. avenaceum and F. graminearum, were positively associated, suggesting that glyphosate might cause changes in fungal communities. Previous glyphosate applications were also correlated positively with F. avenaceum and negatively with C. sativus on crop residues. These studies established a relationship between previous glyphosate use and increased Fusarium colonization in wheat and barley. Because of the close association between non-cereal crops, reduced tillage and glyphosate use, it was not possible to completely separate the effects of these factors on disease development. Research aimed at elucidating the nature of the association between previous glyphosate use and Fusarium crop infections is underway.

Priming induced systematic resistance and susceptibility to fusarium head blight in wheat. N. A. FOROUD, B. E. ELLIS AND F. EUDES. (N.A.F., F.E.) Lethbridge Research Centre, Agriculture and Agri-Food Canada, P.O. Box 3000, Lethbridge, AB T1J 4B1, Canada; and (N.A.F., B.E.) Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, BC V6T 1Z4, Canada

Two major forms of resistance to fusarium head blight have been identified in wheat: type I resistance (resistance to initial infection) and type II resistance (resistance to disease spread). In a recent microarray study, we observed that Fusarium graminearum Schwabe and deoxynivalenol induced upregulation of few defence-related transcripts in the uninoculated spikelets of a type II resistant ‘Sumai 3’-derived line, GS-1-EM0168 (‘CM82036’/‘Superb’*2) compared with type I resistant GS-1-EM0040 (‘CIMMYT 11’/‘Superb’*2). In order to understand the impact of the induced defence-signalling responses on systemic resistance in these lines, we point inoculated a single floret of GS-1-EM0040, GS-1-EM0168 and ‘Superb’ with different inocula, including water, a trichothecene non-producing F. graminearum mutant (Tri5-), and deoxynivalenol. Eight hours after point inoculation, the plants were spray inoculated with an aggressive F. graminearum strain (Tri5+), and evaluated for disease severity at 7, 9, 12 and 18 days after inoculation. Priming of wheat spikes with Tri5- and deoxynivalenol increased type I resistance in GS-1-EM0040, had no impact on resistance in GS-1-EM0168, and increased susceptibility in ‘Superb’. Based on the defence pathways differentially regulated in the microarray study, we believe the susceptible response is due to increased salicylate production and the type I resistance response to increased jasmonates production. We are currently testing this hypothesis.

Progress in breeding for fusarium head blight resistance in Canadian spring wheat – 2009. S. L. FOX, J. T. THOMAS, P. HUCL, C. POZNIAK, R. M. DEPAUW, A. SINGH, R. E. KNOX, P. D. BROWN, D. G. HUMPHREYS AND H. S. RANDHAWA. Cereal Research Centre, Agriculture and Agri-Food Canada (AAFC), 195 Dafoe Road, Winnipeg, MB R3T 2M9, Canada; (P.H., C.P.) Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK SN7 5A8, Canada; (R.M.D., A.S., R.E.K.) Semiarid Prairie Agriculture Research Centre, AAFC, P.O. Box 1030, Swift Current, SK S9H 3X2, Canada; and (H.S.R.) Lethbridge Research Centre, AAFC, P.O. Box 3000, Lethbridge, AB T1J 4B1, Canada

Breeding for resistance to fusarium head blight (FHB) caused by Fusarium graminearum Schwabe continues to be a primary objective for spring wheat breeding programs in western Canada, and the breeding effort is more relevant now due to the recognition that this pathogen is present in Alberta. Progress in the various spring wheat market classes since 2005 is evident in several indices including increased frequency of lines with potential resistance, increased frequency of lines with characterized FHB genes/quantitative trait loci (QTL) and the recent successful registration of three cultivars that are moderately resistant to FHB. However, no FHB resistant cultivars have been registered. Advancement in the art of breeding for FHB resistance is apparent in improvements in field nursery operation resulting in reliable annual results, ease of marker assessment due to fine mapping of FHB QTL regions and rapid throughput marker platforms, merging research information into breeding programmes and identification of elite lines with intermediate, uncharacterized background resistance. Several breeding technology improvements are required including a review of the fine mapping around the FHB 6B QTL, utilization of other resistance sources, rapid assessment of FDK, expansion of deoxynivalenol testing and the impact of stacking known QTLs for FHB resistance into elite backgrounds.

A comparison of the effects on disease ratings of 3ADON and 15ADON chemotypes of Fusarium graminearum on spring wheat. V. GAUTHIER, A. BRULE-BABEL, W. G. D. FERNANDO AND J. GILBERT. Department of Plant Science, 222 Agriculture Building, 66 Dafoe Road, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; and (J.G.) Cereal Research Centre, Agriculture and Agri-Food Canada, Winnipeg, MB R3T 2M9, Canada

Fusarium graminearum Schwabe is the most common causal agent of fusarium head blight (FHB) of wheat in Canada. Presence of the pathogen results in losses in yield and quality. Production of the mycotoxin deoxynivalenol (DON) by the pathogen also limits the uses for feed and food. Recently, it has been shown that the higher DON producer, 3-acetyl DON (3ADON) is replacing the 15-acetyl DON (15ADON) chemotype populations in western Canada. The objective of this study was to evaluate the interaction between 25 F. graminearum isolates which differ in chemotype production and three spring wheat genotypes which differ in reaction to F. graminearum. In 2008 and 2009, each trial was a split plot with three replicates. Fusarium graminearum isolate was the main plot effect and wheat genotype was the sub-plot effect. Each plot was inoculated with a macroconidial suspension containing 50 000 macroconidia mL⁻¹ at anthesis and three days later. Data from both years showed significant differences among isolates and genotypes for area under the disease progress curve. In 2008, there were significant differences for the isolate × genotype interaction, but not in 2009. Disease progressed similarly for all 3ADON isolates but there were differences among the 15ADON isolates. In general, 3ADON isolates produced higher levels of disease than the 15ADON isolates.

Molecular identification and databases in Fusarium . D. M. GEISER, S. KANG AND K. O'DONNELL. Department of Plant Pathology, The Pennsylvania State University, University Park, PA 16802, USA; and (K.O.) Microbial Genomics and Bioprocessing Research, National Center for Agricultural Research, USA Department of Agriculture, Peoria, IL 61604, USA

DNA sequence based methods for identifying Fusarium isolates have become standard as molecular technologies are increasingly available worldwide, and as more data are available in sequence databases for comparative purposes. Unfortunately, the use of BLAST against GenBank as an identification tool is in some ways becoming less reliable, as GenBank cannot possibly curate all submitted sequences and annotation for accuracy, and isolates associated with sequences are not necessarily available to researchers. In 2004, we released the first version of FUSARIUM-ID, a translation elongation-factor 1-alpha database of Fusarium on a BLAST server. All sequences in the database are from isolates that are available for distribution from major culture collections. An updated version of the database was released in late 2008, with additional features including cross-reference to strain information and downloadable sequence data from multiple loci. These resources were discussed and an outline presented of the author's ultimate goals to create a comprehensive bioinformatics resource that facilitates collaboration and integrates culture collection resources and phenotypic and genotypic data.

Alberta seed testing laboratory perspectives – Fusarium graminearum testing methodology and detection. H. GELECH AND K. ZAYCHUK. BioVision Seed Labs, 7225 B Roper Road, Edmonton, AB T6B 3J4, Canada; and (K.Z.) 20/20 Seed Labs Inc, Suite 201, 509-11^th Avenue, Nisku, AB T9E 7N5, Canada

The 1999 declaration of Fusarium graminearum Schwabe in Alberta's Agricultural Pest Act resulted in the 2002 release of AAFRD's Alberta F. graminearum Management Plan. A crucial component of the plan is the requirement for all cereal grains intended for seed use to be tested for the presence of F. graminearum. Since the inception of the plan in 2002, tens of thousands of cereal grain seed samples have been tested in Alberta using one (or both) of two testing methodologies (the whole seed PDA plate culture or a PCR method). Between the 2001/2002 and the 2008/2009 crop years, the number of wheat samples testing positive for F. graminearum has increased from 4.6% to over 15% in southern Alberta whereas infection in cereal samples submitted from northern Alberta is rare. PCR data, which analyzes large samples with high sensitivity, suggest that the percentage of wheat samples testing positive across Alberta has doubled annually since 2006. Plate tests, used to quantify the number of seeds infected with F. graminearum within a sample (≥ 0.5%), further shows that the highest level of infection detected in the 2008/2009 crop year from southern Alberta was 15.5%, with an average infection level of 1.86%. Fusarium graminearum is detected in other cereals in Alberta to a much lesser extent.

Recovery of Fusarium graminearum chemotypes from the 2008 FHB nursery at Glenlea, Manitoba. J. GILBERT, R. M CLEAR AND D. GABA. Cereal Research Centre, Agriculture and Agri-Food Canada, 195 Dafoe Road, Winnipeg, MB R3T 3E5, Canada; and (R.M.C., D.G.) Grain Research Laboratory, Canadian Grain Commission, 1404-303 Main Street Winnipeg, MB R3C 3G8, Canada

Fusarium head blight (FHB) is a serious threat to the Canadian grain industry. Most isolates of Fusarium graminearum Schwabe, the principal cause of FHB in North America, produce the mycotoxin deoxynivalenol (DON) and one of its acetylated derivatives, 3ADON or 15ADON. In North America, a rapid shift from the 15ADON to 3ADON chemotype has been documented. While the 3ADON isolates are not more aggressive than the 15ADON isolates, they produce significantly more DON. The wheat FHB screening nursery at Glenlea, MB was inoculated with a macroconidial suspension of both chemotypes in equal ratio. The objective of this study was to determine if isolates of 3ADON or 15ADON were recovered in the same ratio as applied. A set of six check cultivars/lines, planted throughout the nursery, was sampled after harvest in 2008. For each check variety, 100 seeds were surface-sterilized and plated on potato dextrose agar. The first 40 isolates of F. graminearum recovered per check were single-spored and analyzed for chemotype by PCR. The ratio of 3ADON to 15ADON isolates recovered from seed was on average 4:1, respectively, for all six checks. The 3ADON chemotypes appear to effectively outcompete 15ADON isolates for space and resources on wheat heads.

Potential utility of RT-PCR to detect and quantify Fusarium spp. causing fusarium head blight in oat. T. GREWAL, W. YAN, W. YAJIMA, X. M. ZHANG, A. BEATTIE AND B. ROSSNAGEL. Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada; (T.G.) Saskatchewan Research Council, 125-15 Innovation Boulevard, Saskatoon, SK S7N 2X8, Canada; and (W.Y.) Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Potential significant economic losses from a widespread outbreak of fusarium head blight (FHB) in oat necessitate development of effective disease management strategies. The absence of visual FHB symptoms on oat requires the use of relatively expensive toxin analysis or time-consuming culturing of fungi on appropriate growth media for disease diagnosis. The Crop Development Centre, University of Saskatchewan has initiated a research project (partially funded by the Western Grains Research Foundation) in which a PCR-based assay to detect and quantify the presence of DNA specific to Fusarium spp. responsible for FHB on oat is being developed. Advantages of such an assay include simplicity, sensitivity and speed. Here we report the standardization of a real-time PCR assay using TaqMan technology to detect and quantify Fusarium graminearum Schwabe in oat plants infected in controlled environments. Subsequent deoxynivalenol (DON) analysis revealed a relatively strong positive correlation (r = 0.75) between DON accumulation and abundance of F. graminearum DNA on infected oat. Primer and probe combinations that can specifically detect and quantify F. poae (Peck) Wollenw., F. culmorum (W.G. Smith) Sacc., F. avenaceum (Fr.) Sacc. and F. sporotrichioides Sherb. have also been generated. Results of a 2009 survey of Saskatchewan oat fields to determine prevalence and severity of Fusarium spp. using the RT–PCR assay are also presented.

Effect of three spray inoculation protocols on fusarium head blight infection of cultivars of common wheat and of durum wheat. A. T. GUERRIERI, A. BRULE-BABEL, W. G. D. FERNANDO AND J. GILBERT. Department of Plant Science, University of Manitoba, 222 Agriculture Building, 66 Dafoe Road, Winnipeg, MB R3T 2N2, Canada; and (J.G.) Cereal Research Centre, Agriculture and Agri-Food Canada, 195 Dafoe Road, Winnipeg, MB R3T 2M9, Canada

Fusarium head blight (FHB) caused by Fusarium graminearum Schwabe is a serious disease of wheat capable of causing severe losses in yield and quality. Reliable measurement of cultivar FHB reaction is key to successful resistance breeding. The objective of this study was to compare the effect of three commonly used field macroconidial inoculation protocols on expression of resistance in eight cultivars of spring wheat and two cultivars of durum wheat that differ in reaction to FHB. For the three protocols, plots were inoculated at: (1) 50% anthesis and three days later; or (2) first anthesis and then at three-day intervals until the end of anthesis; or (3) the beginning of heading and at three-day intervals until the soft dough stage. An uninoculated control was also included. Disease incidence and severity were measured at three-day intervals from the onset of first symptoms through to senescence. Although there were absolute differences in disease incidence and severity among the protocols over two years of testing, relative ranking of cultivars was consistent and highly correlated across inoculated protocols. As anthesis is the stage of maximum susceptibility, differences in time to anthesis between cultivars required that comparisons of cultivar disease reactions be made at a consistent time from anthesis.

Competitive ability of 3ADON and 15ADON chemotypes of Fusarium graminearum after spray inoculation of spring wheat. A. T. GUERRIERI, R. CLEAR, A. BRULE-BABEL, W. G. D. FERNANDO AND J. GILBERT. Department of Plant Science, University of Manitoba, 222 Agriculture Building, 66 Dafoe Road, Winnipeg, MB R3T 2N2, Canada; (R.C.) Grain Research Laboratory, Canadian Grain Commission, 1404-303 Main Street, Winnipeg, MB R3C 3G8, Canada; and (J.G.) Cereal Research Centre, Agriculture and Agri-Food Canada, 195 Dafoe Road, Winnipeg, MB R3T 2M9, Canada

Fusarium head blight of wheat caused by Fusarium graminearum Schwabe is of great significance to western Canadian grain producers, processors and consumers. A shift in population structure of F. graminearum has occurred from the 15ADON chemotype to the more toxigenic 3ADON chemotype. The objective of this study was to elucidate the cause of the recent and rapid shift in population structure. Five wheat lines were spray-inoculated in the field with an equal number of macroconidia of two 15ADON isolates and two 3ADON isolates. An uninoculated control was also included. Four hundred isolates were recovered from the harvested seed, grown in pure culture, and the chemotype determined by PCR. Chi-square tests of pooled results for single spore isolations failed to fit a 1:1 ratio for 3ADON:15ADON, with 3ADON being the more abundant chemotype. The results suggest that the 3ADON chemotype is considerably more competitive on the wheat spike than the 15ADON chemotype. This difference could be one reason for the rapid population shift occurring in Canada.

Thinopyrum elongatum as a novel source of fusarium head blight resistance. S. GULDEN, E. WATSON, S. MILLER, G. FEDAK AND T. OUELLET. Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Very few sources of resistance to fusarium head blight (FHB) have been identified in wheat and other cereal crops. Thinopyrum elongatum (2n = 14, EE genome), a wild relative of wheat, was identified as carrying a strong resistance to FHB on its chromosome 7E. In this report, we have used disease rating data, fluorescence microscopy and a modified strain of Fusarium graminearum Schwabe expressing a green fluorescent protein to characterize the resistance carried by chromosome 7E when expressed in the susceptible wheat background of Chinese Spring (CS). Our observations of infected wheat heads showed that inoculated spikelets were less infected in the addition line, than in the parental line CS. Even more striking was the progression of the fungus from the inoculated spikelet to the adjacent node and rachis tissues: the fungus spreads easily and extensively from the inoculated spikelet into the node and adjacent spikelets in susceptible CS heads, but is effectively blocked from spreading in the addition line. Microscopic data clearly showed fungal growth was inhibited within the inoculated spikelet in heads of the addition line and that the fungus was completely blocked from spreading by the node tissue. Taken together, these observations suggest that T. elongatum chromosome 7E carries a novel allele for resistance to spread (Type II resistance) of F. graminearum.

An alternative path to fusarium head blight-resistant wheat cultivars: expression rather than introgression. S. HABER, J. GILBERT AND D. L. SEIFERS. Cereal Research Centre, Agriculture and Agri-Food Canada, 195 Dafoe Road, Winnipeg, MB R3T 2M9, Canada; and (D.L.S.) Kansas State University-Hays, Hays, KS 67601-9228, USA

Decades of sustained effort attest to the difficulty of generating fusarium head blight (FHB)-resistant spring wheat cultivars. The common assumption underlying these efforts is that discrete genes conditioning superior FHB resistance must be introgressed from sources such as ‘Sumai 3’ into elite germplasm. An alternative path could start from a very different assumption. FHB-susceptible near-isogenic lines of ‘Sumai 3’, like ‘Sumai 3’ itself, carry pathogenesis-related genes that are induced by Fusarium graminearum Schwabe. This suggests that the key to FHB resistance is the control of expression of critical genes that are already present. A scheme that might generate variation in expression was suggested when we observed that progeny derived by selfing of plants under pressure from systemic virus infection could vary visibly from type. We devised an iterative protocol which, even within small populations, selects such variants and identifies by their expression in subsequent generations those whose altered traits are heritable. Promising individuals are then advanced as founders of lines for testing. Within three years we have thus derived lines from the doubled haploid cultivar ‘McKenzie’ that express traits not seen in their progenitor: short stature, near-immunity to wheat streak mosaic virus, and improved resistance to leaf spot diseases and FHB. These new characteristics have been stably expressed over multiple generations.

Yeast genomic screening to identify cellular targets of Fusarium graminearum fungal toxins. A. HERMANS, L. MITCHELL, K. BAETZ, W. BOSNICH, L. HARRIS AND S. GLEDDIE. Eastern Cereal and Oilseed Research Centre, Agriculture and AgriFood Canada, 960 Carling Avenue, Ottawa, ON K1A0C6, Canada; and (L.M., K.B.) Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON K1H 8M5, Canada

The extensive homology between yeast and higher eukaryotic biochemical pathways means that high-throughput chemogenomic profiling in yeast has become a very powerful method to find drug and toxin targets. The yeast community has produced haploid non-essential gene deletion collections, heterozygous deletion collections and over-expression collections (http://www.yeastgenome.org). We have been using these resources to screen for cellular targets of the major mycotoxin produced by the cereal pathogen Fusarium graminearum Schwabe. We highlighted our results of four genome-wide screens of the heterozygous deletion collection against sub-lethal doses of the mycotoxin deoxynivalenol (DON) which contributes to the virulence of this pathogen against cereals. From these screens, we have selected a number of yeast strains whose gene deletions have resulted in either increased or decreased sensitivity to DON. The effect of these gene deletions on yeast cell tolerance to DON was validated by sensitive real-time liquid growth assays in the presence of toxin for a 24 h period. DON is known to bind to the eukaryotic ribosomal protein L3 (RPL3), inhibiting protein synthesis. This screen has identified genes expected to be associated with DON tolerance/sensitivity such as those involved in protein synthesis, folding, transport as well as some novel targets. We will discuss the elucidation of the targets and mode of action of this mycotoxin.

Shotgun proteomics gives insight into reversible redox modifications in double Nox mutants of Fusarium graminearum . M. JOSHI, C. RAMPITSCH AND R. SUBRAMANIAM. Cereal Research Centre, Agriculture and Agri-Food Canada (AAFC), 195 Dafoe Road, Winnipeg, MB R3T 2M9, Canada; and (R.S.) Eastern Cereal and Oilseed Research Centre, AAFC, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Shotgun proteomics, a strategy integrating protein digestion into peptides and sequencing through mass spectrometry, has become the method of choice for identification of key proteins in complex mixtures. We have used a shotgun redox proteomic technique to identify the reversibly modified cysteine groups in double mutants of Fusarium graminearum Schwabe. The fungus is mutated for NADPH oxidase (Nox) A and B genes. The free cysteines groups were blocked with IAA followed by reduction of oxidised cysteines with DTT and biotin-affinity chromatography was used to isolate a ‘redox subpeptidome’ which permits selective targeting of redox sensitive cysteines that undergo reversible modification. The reversible post translational modifications of thiol groups influence the protein's structure and function and control a broad spectrum of biochemical processes, including redox regulation, protection against oxidative stress and cell signalling. In this study, we are using a gel-free approach to detect redox sensitive cysteines within key proteins in double Nox mutants of F. graminearum in order to elucidate the mechanism involved in disease progression through the reduction/ oxidation of disulphide bonds in a pathway that includes NADPH oxidase A and B enzymes.

Development of transgenic maize plants expressing GFP, a marker gene and DON detoxifying gene, Tri101 for Fusarium resistance. P. KANT, B. NASH AND K. P. PARLS. Department of Plant Agriculture, University of Guelph, Guelph, ON N1G 2W1, Canada

Fusarium graminearum Schwabe (teleomorph Gibberella zeae (Schw.) Petch) causes fusarium/gibberella ear rot disease in maize. This is a major disease problem for maize production in North America, Europe and China. The current report describes progress in our efforts to develop resistance to gibberella ear rot in maize by transformation with genes that may provide resistance against F. graminearum. An Agrobacterium-mediated transformation system was used to transform maize multiple shoot meristems cultures initiated from apical shoot meristems of seedlings. Presently we have developed transgenic corn plants expressing deoxynivalenol (DON) detoxifying gene, Tri101 encoding trichothecenes 3-o-actetyltrasferease, whose product converts DON to a less toxic derivative, 3-acetyldeoxynivalenol (3ADON). The gene was obtained from our collaborators in Hebrew University of Jerusalem, Rehovot, Israel. Transgenic plants developed were confirmed for the presence and expression of GFP or Tri101 gene with southern analysis and reverse-transcriptase PCR, respectively. All transgenic plants were fertile and set seeds. Tests of the ability of the transgenic kernels to detoxify DON are currently being performed and studies of the enzymatic activity of the TRI101 protein will be carried out. Our work suggests that corn transformation with genes that interfere with the disease or detoxify DON are good approaches to enhancing the resistance of maize to F. graminearum.

What has been learned from six years of genomic research on the fusarium head blight pathogen? H. C. KISTLER. USDA, ARS, Cereal Disease Laboratory, 1551 Lindig Street, University of Minnesota, St. Paul, MN 55108, USA

Since its first public release in May 2003, the genome sequence of Fusarium graminearum Schwabe (Fg) has guided a broad range of research on fusarium head blight disease and toxicology. Using genomic information, over two dozen genes essential for full pathogenicity of the fungus have been identified. The basic genetic framework involved in pathogenicity for Fg consists of elements highly conserved with other fungi as well as pathways specific to Fg and closely related species. Microarrays have been designed based on the Fg genome sequence and these tools have led to a greater understanding of developmental processes essential for disease initiation and reproduction of the fungus such as spore germination and perithecium formation. Fundamental studies on the regulation of mycotoxin accumulation also have been aided by whole genome sequence information. My talk summarized these recent advances in genome biology and prospects for rational disease control and toxin reduction based on fundamental knowledge of pathogen biology.

Introgression of two QTLs from exotic source in adapted European wheat. V. KORZUN, C. KNOPF, E. EBMEYER AND T. MIEDANER. KWS LOCHOW GMBH, Ferdinand-von-Lochow-Str.5, 29303 Bergen, Germany; and (C.K., T.M.) University of Hohenheim, State Plant Breeding Institute, 70593 Stuttgart, Germany

At the beginning of the 21st century, mankind faces the challenge of feeding a growing population with increasing demands in the quality of food. Land and water resources are limited and threatened by degradation worldwide. Forecasts of climate change indicate additional uncertainty and place even more pressure on our natural resources to provide enough food for everyone. Fusarium head blight (FHB) is one of the most important wheat diseases that cause yield and quality losses as well as contamination with deoxynivalenol (DON). This study presented here was aimed at the marker-based introduction of two previously mapped quantitative trait loci (QTL) from the exotic resistance source ‘Sumai 3’ into an elite background of two German winter wheat varieties. Phenotypic selection is a current method to improve FHB resistance in wheat breeding in Europe by exploiting the existing variability of a lot of loci with small effects in adapted and elite germplasm. Markers for several QTL have been published that may be useful for the development of FHB resistant cultivars in the future. The aim of this study is (1) to validate the effectiveness of the resistance from the exotic ‘Sumai 3’, and (2) to examine the amount of linkage drag on agronomic traits. Detailed results of this study will be presented and discussed.

Sources of type II Fusarium resistance for triticale breeding. F. LANGEVIN, F. EUDES, A. COMEAU, Y. DION, S. RIOUX, H. RANDHAWA, G. FEDAK, W. CAO, J. GILBERT, C. LACHANCE AND D. SALMON. Soils and Crops Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), 2560 Hochelaga Boulevard, Québec, QC G1V 2J3, Canada; (F.E., H.R.) Lethbridge Research Centre, AAFC, P.O. Box 3000, Lethbridge, AB T1J 4B1, Canada; (Y.D.) Centre recherché sur les grains, 740 chemin Trudeau, Saint-Mathieu-de-Beloeil, QC J3G 0E2, Canada; (S.R.) Centre recherché sur les grains, 2700, rue Einstein, Québec, QC G1P 3W8, Canada; (G.F., W.C.) Eastern Cereal and Oilseed Research Centre, AAFC, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; (J.G.) Cereal Research Centre, AAFC, 195 Dafoe Road, Winnipeg, MB R3T 2M9, Canada; and (D.S.) Field Crop Development Centre, Alberta Agriculture and Rural Development, 5030-50 Street, Lacombe, AB T4L 1W8, Canada

Triticale lines have been assessed in field and indoors trials for Fusarium resistance since 2006. In artificially inoculated field trials, Pronghorn had rather consistent MR fusarium head blight (FHB) reaction; however, its lateness also leads to escape, and the presence of type I (resistance to infection) R genes interferes with the observation of other R types. Replicated trials were conducted indoors using point inoculations with Fusarium graminearum Schwabe on 62 triticale lines, to obtain clear evidence of type II R (resistance to spread). Quite strong type II R was found in a few triticale lines (e.g. Trit-910, Trit-875, Trit-1317 and a few others). However, Pronghorn rated only MRMS for type II R. Breeding for type II R should be an easy task, using point inoculation. However, this does not suffice. The challenge in order to get acceptable overall resistance in natural FHB epidemics is to increase also the type I R, and to improve pericarp resistance (a third mechanism), which is inadequate in most current germplasm. Sources of genes for those three mechanisms exist. Gene pyramiding assisted by a systemic approach (including FHB inoculations by spawn, spray and point-inoculation methods) may be ideal for the task, since the desired end result, toxin-free grain, is necessarily under polygenic control.

Update on improving fusarium head blight resistance in Canadian barley. W. G. LEGGE. Brandon Research Centre, Agriculture and Agri-Food Canada, P.O. Box 1000A, R.R. 3, Brandon, MB R7A 5Y3, Canada

Fusarium head blight (FHB) caused by Fusarium graminearum Schwabe is the most important disease of barley in Canada. Good progress has been made over the past decade by Canadian barley breeding programmes in developing FHB resistant cultivars and germplasm with low deoxynivalenol (DON) accumulation. The two-row feed barley cultivar CDC Mindon, registered in 2007, has set the standard with about half the DON content of AC Metcalfe over many years of testing. Two new cultivars, ‘Norman’ and ‘HB705’, resulting from in vitro selection using Fusarium mycotoxins during doubled haploid production were registered in 2009. Norman is a two-row malting cultivar selected from ‘CDC Kendall’ with 25–30% lower DON content than its parent, while HB705 is a two-row hulless cultivar with malting quality potential and lower DON content than other hulless cultivars. Progress has lagged in six-row germplasm. Most programmes are in the second or third breeding cycle, and have better parents available for crossing purposes to enhance FHB resistance. In 2009, the FHB project in western Canada will replace selection based on visual symptoms for most advanced breeding lines with preliminary selection for DON content using near-infrared reflectance (NIR) spectrometry to identify lines for further DON testing with standard methods. Funding constraints may pose a serious challenge to future progress.

Progress in developing fusarium head blight resistant two-row malting barley at Agriculture and Agri-Food Canada's Brandon Research Centre. W. G. LEGGE, J. R. TUCKER, B. BIZIMUNGU, M. BANIK, A. TEKAUZ, R. A. MARTIN, T. M. CHOO AND M. E. SAVARD. Brandon Research Centre, Agriculture and Agri-Food Canada (AAFC), P.O. Box 1000A, R.R. 3, Brandon, MB R7A 5Y3, Canada; (B.B.) Lethbridge Research Centre, AAFC, P.O. Box 3000, Lethbridge, AB T1J 4B1, Canada; (M.B., A.T.) Cereal Research Centre, AAFC, 195 Dafoe Road, Winnipeg, MB R3T 2M9, Canada; (R.A.M.) Crops and Livestock Research Centre, AAFC, 440 University Avenue, Charlottetown, PE C1A 4N6, Canada; and (T.M.C, M.E.S.) Eastern Cereal and Oilseed Research Centre, AAFC, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Fusarium head blight (FHB) caused by Fusarium graminearum Schwabe continues to be the most destructive disease of barley in Canada. Development of FHB resistant cultivars with low deoxynivalenol (DON) accumulation has been an important objective of the two-row malting barley breeding program at Agriculture and Agri-Food Canada, Brandon, MB, for the past decade. To hasten progress, doubled haploid lines were produced with many subjected to in vitro selection (IVS) using culture media containing Fusarium mycotoxins. TR05915, an IVS selection from ‘CDC Kendall’ showing 25–30% lower DON content than ‘CDC Kendall’ while maintaining its desirable quality profile, was recently registered as Norman. ‘HB705’, an IVS selection from the ‘CDC Freedom’/ ‘Rivers’ cross, was also registered as a two-row hulless cultivar with malting quality potential. ‘HB705’, which combines reduced DON content relative to other hulless cultivars with high malt extract, may be attractive to the malting and brewing industry. Using exotic parents, such as two-row Chinese accession Harbin, to enhance FHB resistance has been attempted with limited success. A second breeding cycle is currently underway; TR08203, a promising line tracing back to Harbin, was advanced to a second year in the 2009 Western Cooperative Two-row Barley Registration Test. Numerous FHB resistant breeding lines at various stages of development will be evaluated further in 2009.

Coordinated regulation by Tri10 and Tri6 in Fusarium graminearum . W. LEUNG, C. NASMITH, L. WANG, A. JOHNSTON, L. HARRIS AND R. SUBRAMANIAM. Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Fusarium graminearum Schwabe is a globally distributed fungal pathogen that causes disease in cereal crops such as wheat and barley and it also contaminates host plants with secreted mycotoxins such as deoxynivalenol. Consumption of infected or contaminated cereal products is hazardous to animals, as a result, fungal infection and contamination causes major economic losses in agriculture industries worldwide. Gene expression profiling of Tri10Δ and Tri6Δ mutant strains under deoxynivalenol (DON)-inducing conditions in culture provided evidence that the regulatory roles of the two studied genes extend beyond the trichothecene biosynthesis pathway. They are potential regulators of another clustered secondary metabolic pathway – butenolide biosynthetic pathway. Furthermore, Tri10 and Tri6 also regulate genes that might contribute to virulence of F. graminearum. In addition to the previously proposed model where Tri10 and Tri6 are independently regulated, we have evidence to show that Tri6 auto-regulates its own expression.

Relationship between incidence of fusarium head blight, tombstone kernels and deoxynivalenol concentration of spring wheat as affected by planting and harvesting dates, and nitrogen fertilization. B. L. MA, K. D. SUBEDI, A. G. XUE AND H. D. VOLDENG. Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Proper crop management is an important strategy to reduce deoxynivalenol (DON) concentrations in the grain of spring wheat. A field experiment was conducted at two sites in Ottawa, Canada for three growing seasons to investigate DON concentration, visual assessments and their relationships to planting and harvesting dates and nitrogen (N) application. The cultivar ‘AC Brio’ was seeded at three planting dates with five N treatments. At early dough stage, each plot was surveyed for fusarium head blight (FHB) infestation. From physiological maturity (PM), plant samples were taken at weekly intervals, and grain and plant moisture contents determined. The Fusarium-damaged tombstone kernels (FDK) were counted and the kernel samples ground and analyzed for DON concentration. For both soil types, later planting significantly increased the FDK count and DON concentration in the grain. The effect of late planting was greater in coarse-textured sandy loam than in a fine-textured loam or clay loam soil. DON concentration was significantly increased when harvest was delayed from two to four weeks after PM. There was often weak or no correlation between FHB incidence and grain DON concentration. Our data indicate that under the eastern Canadian conditions, some precautionary practices such as early seeding and timely harvest will reduce the incidence of FDK and DON content.

Association of morphological and developmental traits with fusarium head blight in a population of wheat derived from a cross of wheat cultivar ‘Brio’ and a Triticum timopheevii line. A. MALIHIPOUR, J. GILBERT, A. BRÛLÉ-BABEL, G. FEDAK AND W. CAO. Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; (A.M, J.G.) Cereal Research Centre, Agriculture and Agri-Food Canada (AAFC), 195 Dafoe Road, Winnipeg, MB R3T 2M9, Canada; (A.B.) Department of Plant Science, 222 Agriculture Building, 66 Dafoe Road, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; and (G.F., W.C.) Eastern Cereal and Oilseed Research Centre, AAFC, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Fusarium head blight (FHB) is one of the most devastating diseases of wheat. In a population of recombinant inbred lines derived from the cross of bread wheat cultivar ‘Brio’ and a Triticum timopheevii line, the association of morphological and developmental traits (number of days to anthesis, height and presence/absence of awns) with disease-related variables [disease incidence, disease severity, disease index and Fusarium-damaged kernels (FDK)] was investigated. The evaluations were done in single-floret-inoculated trials in the greenhouse and spray-inoculated field experiments in two locations. Results showed that the number of days to anthesis had significant negative correlation with disease incidence, disease severity and disease index in 2006 (−0.2543, −0.4119, and −0.3572, respectively at P ≤ 0.01) but positive correlation with FDK (0.3080 at P ≤ 0.01). In the greenhouse, where only disease severity was assessed, correlation of the number of days to anthesis and plant height with disease severity was relatively low (0.1762 at P ≤ 0.01) or not significant, respectively. The presence of awns in plants significantly reduced the level of disease in both field (disease incidence, severity, index and FDK) and greenhouse (disease severity) conditions. These results generally support the results of earlier FHB studies and should be considered when breeding wheat genotypes for resistance to FHB.

Integrated management of fusarium head blight – research and outreach. M. MCMULLEN. Department of Plant Pathology, North Dakota State University, Walster Hall, Fargo, ND 58102, USA

Fusarium head blight (FHB) is a difficult disease to manage, and under environmental conditions favourable for FHB development, use of just a single management strategy may result in management failure. In the past decade, more FHB management research has focused on use of multiple techniques, and today, most published FHB management recommendations encourage an integrated approach. In 2007, the US Wheat and Barley Scab Initiative (USWBSI) began a multi-state research effort to examine use of two or more strategies in managing this disease; the goal was to demonstrate to grain producers the value of an integrated approach. For example, research in North Dakota in 2007 showed an incremental improvement in reducing FHB parameters and increasing yield, by stacking strategies. The primary strategies examined in these USWBSI sponsored integrated studies have been host resistance, crop rotation and fungicide use. Disease levels have varied considerably across years and locations, but integrated strategies have proven reliable, regardless of disease level. An update on results of these USWBSI sponsored integrated management studies, as well as information on a new US outreach effort called Scab Smart (www.scabsmart.org), was presented.

Breeding for resistance to ear rot and tolerance to mycotoxins in European maize. T. MIEDANER, M. LOEFFLER, B. KESSEL AND M. OUZUNOVA. State Plant Breeding Institute, Universitaet Hohenheim (720), Fruwirthstr. 21, D-70799 Stuttgart, Germany; and (B.K, M.O) KWS SAAT AG, Grimsehlstr. 31, D-37555 Einbeck, Germany

Maize was grown in the European Union (EU27) in 2008 on 14 million hectares, 37% thereof as silage maize (DMK 2009). In the northern parts of Europe, ear rot is primarily caused by Fusarium graminearum Schwabe (Fg), while in southern Europe, Fusarium verticillioides (Sacc.) Nirenberg (Fv) prevails. Three maturity groups (early, mid-late and late) were evaluated separately for resistance to Fv and Fg across two years. The early maturity group consisted of 50 flint and 90 dent inbred lines, the mid-late and late group of 147 and 148 dent lines, respectively. All lines were current breeding lines of the KWS SAAT AG. The results showed that chances for selecting improved European elite maize material is promising by multi-environmental inoculation trials. Separate testing of Fg and Fv is necessary since genotypes resistant to deoxynivalenol (DON) or ZEA were not necessarily resistant to FUM accumulation. Test crosses must be tested separately because the resistance of inbreds alone does not allow a secure prediction. Breeding for resistant varieties is an urgent need in view of the high mycotoxin contents found even in less-infected samples.

Transcriptional profiling of maize kernels infected with Fusarium graminearum . M. MOHAMMADI, W. BOSNICH, D. SCHNEIDERMAN, A. JOHNSTON, P. COUROUX, N. TINKER AND L. HARRIS. Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Fusarium graminearum Schwabe is the causal agent of gibberella ear rot in maize. Transcriptional profiling enriches our knowledge of the molecular response of maize kernels to F. graminearum. Two maize inbred lines (B73 and CO441), differing in their susceptibility to F. graminearum infection, were selected. Comparisons of transcript abundance were conducted by hybridizations of maize long oligomer microarrays (representing 58K transcripts) with RNA isolated from F. graminearum-treated kernels and (i) untreated kernels and (ii) mock-treated kernels. By comparing the results obtained with those previously reported for trichothecene-responsive transcripts in wheat and barley, we have divided our discussion into two sections: (a) genes for which previous evidence exists showing that they are more likely induced upon trichothecene accumulation (e.g. glucosyltransferases, transporters); and (b) genes that are putatively induced independent of trichothecenes and as a result of pathogen invasion per se (e.g. pathogenesis-related proteins, peroxidases, and proteins involved in plant hormonal responses, cell wall modifications, and secondary metabolism biosynthesis).

Fighting Fusarium with Fusarium – priming for FHB protection in wheat. C. NASMITH, R. SUBRAMANIAM AND L. WANG. Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Attempts to control Fusarium graminearum Schwabe, the causal agent for fusarium head blight (FHB), have involved chemical and biological approaches, along with resistance breeding. Priming, a more recently characterized control strategy, involves innate plant immunity through microbe perception. In this study, priming is tested with three targeted gene-disrupted mutants including NADPH oxidase, MGV1 map kinase, and the trichothecene regulator Tri6. All three genes have diverse functions, but mutants display similar non-virulent disease phenotypes on wheat. The Tri6 mutant was first tested for various parameters associated with priming including priming load, priming window and challenge load, on the FHB susceptible wheat variety Roblin. Wheat heads were first inoculated (primed) with the Tri6 mutant, and then after 24 h, the wild-type progenitor strain was inoculated (challenged). Following 21 days the Tri6 mutant drastically reduced disease symptoms compared to mock controls. The NADPH oxidase mutant reduced symptoms as well, but the MGV1 mutant showed no difference in disease reduction compared with mock controls. Priming works, and is presently being investigated both as a biological control, and as the basis for continuing wheat expression studies, as a novel procedure to characterize FHB-resistant wheat germplasm.

Rapid optical sorting of Fusarium -infected wheat. D. A. PRYSTUPA. Spectrum Agricultural Inc., P.O. Box 883, 402 Ara Mooradian Way, Pinawa, MB R0E 1L0, Canada

A colour sorter for identifying and removing Fusarium-damaged kernels in wheat has been developed. The device singulates wheat kernels, makes a series of measurements at two wavelengths, classifies kernels as ‘infected’ or ‘healthy’ and directs infected kernels into a separate stream. The classification accuracy is 92.4% for ‘healthy’ kernels and 93.4% for ‘infected’ kernels. The deoxynivalenol concentration is reduced by an average of 84% by removing the ‘infected’ kernels, in all cases to less than 1 ppm. The process is economic at $10 per tonne.

Salicylic acid inhibits the germination and growth of Fusarium graminearum and improves the resistance of wheat to fusarium head blight. P. F. QI, T. OUELLET, Y. M. WEI AND Y. L. ZHENG. (P.F.Q., Y.M.W., Y.L.Z.) Triticeae Research Institute, Sichuan Agricultural University, Yaan, Sichuan 625014, PR Chin; and (P.F.Q., T.O.) Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Salicylic acid (SA) is one of the key signal molecules in regulating the resistance of plant to diverse pathogens. It is predominantly associated with resistance against biotrophic and hemibiotrophic pathogens, and triggering systemic acquired resistance (SAR). However, whether SA directly affects Fusarium graminearum Schwabe (Fg) and how SA influences the defence efficiency of wheat against fusarium head blight (FHB) are still poorly understood. Here we show that the germination of Fg spores can be significantly reduced by a concentration of SA between 600–800 μM in a modified SNA media, and 1 mM SA can stop Fg germinating. Growth of Fg mycelia can be significantly inhibited under a concentration higher than 1 mM and can be stopped by 5 mM SA. Point inoculation of 10 μL solution containing 400 μM-1 mM SA and 1000 spores can protect a very susceptible Triticum aestivum cultivar ‘Roblin’ away from Fg infection. Further work is needed to differentiate the direct effect of SA from SAR induced by exogenously applied SA. The above results clearly demonstrate that SA has a significant and direct impact on Fg through the reduction of germination and growth rate, and SA could improve the resistance of wheat to FHB.

Strategic application of proteomics and plant genotyping toward improved fusarium head blight resistance in Canadian wheat. C. RAMPITSCH, D. SOMERS, L. TAMBURIC-ILINCIC, G. FEDAK, T. OUELLET, G. HUMPHREYS AND R. DEPAUW. Cereal Research Centre, Agriculture and Agri-Food Canada (AAFC), 195 Dafoe Road, Winnipeg MB R3T 2M9, Canada; (L.T.) Department of Plant Agriculture, University of Guelph, Ridgetown Campus, 120 Main Street East, Ridgetown, ON N0P 2C0, Canada; (G.F., T.O.) Eastern Cereal and Oilseed Research Centre, AAFC, 960 Carling Avenue, Ottawa ON K1A 0C6, Canada; and (R.D.) Semiarid Prairie Agricultural Research Centre, AAFC, P.O. Box 1030 Swift Current, SK S9H 3X2, Canada

This poster described progress from a bilateral project between Canada and Germany, funded under the GABI-Canada collaboration. The project combines traditional breeding, molecular breeding and mapping with ‘-omics’ sciences to mitigate the impact of fusarium head blight (FHB) and its associated mycotoxins in spring and winter wheat. FHB is a major concern in both countries. It is imperative to apply genomics-based science to safeguard Canadian and European wheat. The outcome of this project will be the reduction of mycotoxins in grain by introducing new FHB-resistant wheat cultivars to sustain the multi-billion/year Canadian and German wheat industries and to ensure food and feed safety. In this project three sources of FHB resistance (Asian, Brazilian, European) were pyramided and examined phenotypically and biochemically. The major goals included: introgression of European winter wheat FHB resistance into elite Canadian wheat; introgression of Asian resistance into broader-based Canadian spring wheat genetic platforms using marker-assisted selection; creating a new biochemical understanding of FHB resistance in wheat through comparative proteomics and genomics. This poster summarized progress of the project, principally on the Canadian side, to date.

Protein phosphorylation and deoxynivalenol synthesis – candidate phosphopeptides from wild-type and MAP kinase (MGV1)-deficient Fusarium graminearum . C. RAMPITSCH, R. SUBRAMANIAM, N. V. BYKOVA AND S. DJURIC-CIGANOVIC. Cereal Research Centre, Agriculture and Agri-Food Canada (AAFC), 195 Dafoe Road, Winnipeg, MB R3T 2M9, Canada; (R.S.) Eastern Cereal and Oilseed Research Centre, AAFC, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; and (N.B.) Department of Biology, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada

The steps comprising the synthesis of deoxynivalenol (DON) and its derivatives by Fusarium graminearum Schwabe are well understood, but their regulation at the molecular level is not. We are investigating a potential role for protein phosphorylation in initiating DON synthesis during nitrogen starvation in vitro. We have previously used multidimensional separations and analyses, MUDPiT and GeLCMS, to establish a phosphoproteome map of wild-type F. graminearum, and are now probing the phosphoproteome of MAP-kinase (MGV1)-deficient F. graminearum after the onset of DON synthesis. This mutant produces only about 20% of the DON levels seen in wild-type in vitro. Phosphopeptides were enriched by immobilized metal affinity chromatography and titanium dioxide affinity chromatography. Enriched peptides were analyzed by LC-MS using collision induced dissociation (CID) and electron transfer dissociation (ETD) fragmentation of peptides. The Mascot search engine was used to query a complex fungal sequence database to assign tentative protein identities based frequently on single peptides. All phosphorylation sites were confirmed manually. The biological role of some of these proteins in regulating DON synthesis will be assessed in vivo by producing F. graminearum mutants and measuring both their virulence and ability to produce DON.

QTLs for gibberella stalk rot resistance in maize population CG62 × CO387. Y. REINPRECHT, M. RIAZ, L. M. REID AND K. P. PAULS. Department of Plant Agriculture, University of Guelph, Guelph, ON N1G 2W1, Canada; and (Y.R., M.R., K.P.P.) Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON, K1A 0C6

Gibberella stalk rot caused by Fusarium graminearum Schwabe is prevalent in cool maize-growing regions. The disease can cause extensive crop damage by initiating premature plant death, interfering with the translocation of water and nutrients during grain filling and promoting crop lodging. Previously, a maize recombinant inbred line (RIL) population from the cross CG62 × CO387 was used to map quantitative trait loci (QTL) for gibberella ear rot resistance and seed phenolics. The objective of the current study was to identify QTLs for gibberella stalk rot resistance in the same population by the means of selective phenotyping. Forty RILs (selected based on the seed ferulic acid content) and parental genotypes (CG62 and CO387) were evaluated for gibberella stalk rot and physical/chemical characteristics of the stalk in Ottawa in 2008 and 2009. The RILs were segregating for the stalk rot disease severity ratings and ranged from 4.67 to 7.00 in 2008. Twelve molecular markers were associated with the 2008 disease severity ratings. There was no significant correlation between the 2008 gibberella stalk rot and the previously determined ear rot disease severity ratings. Chemical and physical characterization of the stalk (height, diameter, lodging, phenolics) is underway. After completing the 2009 experiment, the data will be used to map stalk rot QTLs.

Comparative gene expression profiling of major plant hormone pathways during infection by Fusarium graminearum . H. J. ROCHELEAU, W. ZHENG, S. GULDEN, R. XU, L. WANG AND T. OUELLET. Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Plant host defence involves many changes in hormone signalling pathways (jasmonic acid, salicylic acid, gibberellin, auxin, shikimate) for the majority of plant infection diseases. In this study, we examine the molecular basis of the host wheat resistance against Fusarium graminearum Schwabe (Fg) by comparing RNA profiles of key genes of these plant hormone signalling pathways. Differences in RNA transcript levels of three wheat varieties: fusarium head blight (FHB)-susceptible ‘Roblin’, moderately resistant ‘NuyBay’, and very resistant ‘Wuhan’ were determined by the Affymetrix GeneChip Wheat Genome Array and then validated by quantitative PCR (qPCR). RNA was extracted from head tissues sampled at zero, one, two and four days post-inoculation (dpi) with water or Fg spores (100 spores/floret). Each cDNA sample was tested for its relative expression level and normalized using the averaged expression of three reference genes. We observed a major trend among most genes validated: expression varies during the development of infection, is strongly associated with the fungal biomass and also consistent with deoxynivalenol accumulation. The responsiveness of the very infected, susceptible variety ‘Roblin’ contrasted strongly in our study with the modest response observed in the resistant variety ‘Wuhan’. This suggests that, for the pathways analyzed, the level of RNA accumulated is not the major determinant of resistance in ‘Wuhan’.

Cross tolerance to Fusarium spp . in fusarium head blight-tolerant genotypes of spring wheat. Y. F. RUAN, R. BABONICH, C. J. POZNIAK, P. J. HUCL, G. HUGHES AND J. M. CLARKE. Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada

Fusarium head blight (FHB), caused by Fusarium spp., is of interest due to its negative impact on wheat quality and yield. A majority of FHB resistance genes in wheat have been identified based on reaction to Fusarium graminearum Schwabe (Fg). To better understand tolerance to other Fusarium spp. four wheat genotypes with contrasting resistance to Fg were screened with five Fusarium spp. (F. culmorum Sacc., F. poae (Peck) Wollenw., F. graminearum Schwabe, F. avenaceum (Fr.) Sacc. and F. sporotrichioides Sherb.) in the greenhouse. Plants were artificially inoculated with two or three isolates from Manitoba, Saskatchewan and Alberta for each of Fusarium spp. The development of FHB was rated as disease severity (DS) on a 0–5 scale every two days from day 4 to day 22 after inoculation. FHB severity over time was summarized as the area under disease progress curve (AUDPC). Regardless of wheat cultivar, F. culmorum resulted in the greatest disease development. Cultivars resistant to Fg were also resistant to F. culmorum. The Fg tolerant wheat cultivars showed better resistance than the susceptible cultivars, regardless of Fusarium spp. These results suggest that the current tolerance genes deployed in spring wheat provide cross tolerance to all Fusarium spp. currently present in western Canada.

Mapping of QTL for tolerance to fusarium head blight in the tetraploid wheat population TG3487/2*DT735. Y. F. RUAN, C. J. POZNIAK, P. J. HUCL AND J. M. CLARKE. Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada

Most durum wheat (Triticum turgidum L var. durum) is susceptible to fusarium head blight (FHB). To date, few tolerance genes have been identified in durum and none provide adequate tolerance under endemic infection. This study was conducted to identify FHB resistance in tetraploid wheat and map quantitative trait loci (QTL) associated with FHB tolerance. A backcross recombinant inbred line population was developed from the tetraploid cross TG3487/2*DT735. A total of 160 lines were evaluated for type II resistance to Fusarium graminearum Schwabe in greenhouse experiments and in endemic nurseries at Carman, Manitoba in 2008 and 2009. The population was genotyped with approximately 100 microsatellite markers and QTL for FHB severity (greenhouse) and disease incidence, severity and index (field) were identified using single marker analysis. In field and greenhouse studies, TG3487 was tolerant to FHB, with reactions equal to the hexaploid line ND2710. DT735 expressed tolerance better than ‘AC Morse’ and similar to ‘AC Barrie’. In 2008, severity and incidence in the field were not correlated with heading time, but the correlations were significant in 2009. Xwmc349, Xbarc167, Xwmc445 and wmc201 were associated with greenhouse and field tolerance in both years. Efforts are underway to validate these QTL and to further backcross and pyramid these QTL into commercially adapted backgrounds.

Differential effect of chemotypes of Fusarium graminearum on spring wheat. Y. F. RUAN, C. J. POZNIAK, P. J. HUCL AND J. M. CLARKE. Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada

Two trichothecene chemotypes of Fusarium graminearum Schwabe, 3ADON and 15ADON, are the most prevalent chemotypes in Canada. Few studies have examined the interaction of wheat genotype and Fusarium chemotype, which would be valuable in designing resistance breeding strategies. In this study, four tetraploid and three hexaploid wheat genotypes representing different fusarium head blight (FHB) resistance levels were evaluated in replicated greenhouse trails. Spikes were inoculated with one of four isolates (two 3ADON; two 15ADON), and two mixtures containing one isolate of each chemotype. Disease severity was scored at days 7, 14 and 21 after inoculation and recorded as percentage of infected spikelets. Spread of FHB within the heads was assessed by the area under disease progress curve (AUDPC). Compared with the 15ADON chemotype, a higher level of disease development was observed in hexaploid wheat inoculated with the 3ADON chemotype. The opposite was observed in tetraploid wheat except for the susceptible control, and suggests different genetic mechanism(s) of resistance in tetraploid wheat. For all genotypes, a mixture of 3ADON and 15ADON showed similar pathogenicity to individual inoculations with 3ADON or 15ADON chemotype. Our results also indicated that there was some influence of isolate on the pathogenicity within chemotype.

A tale of contrasting economic reaction to mycotoxin in maize and wheat in the same agricultural system in Ontario, Canada. A. W. SCHAAFSMA, D. HOOKER, L. TAMBURIC AND V. LIMAY-RIOS. Ridgetown Campus, University of Guelph, 120 Main Street East, Ridgetown, ON N0P 2C0, Canada

In 1996 Ontario experienced the worst Fusarium epidemic in recent history in wheat. This event precipitated a gathering of industry stakeholders to design strategies to collectively prevent further harm to the sector by supporting and developing an integrated management system. In 13 years this strategy yielded significant progress on: breeding for more tolerant varieties, an improved variety registration system, implementing fungicide recommendations and improving application technologies, developing a pre-harvest forecasting system (DON-Cast) and setting up surveillance strategies and mycotoxin testing. In contrast, more than 20 years have passed since the first severe epidemic of Fusarium in corn in 1986 and very little progress has been achieved toward the development of an integrated approach, as seen in the severe epidemic of 2006. The corn hybrid registration requirements were abandoned approximately 10 years ago. There is a distinct difference between the two commodities in their end use and the associated mycotoxin regulations (feed/industrial for corn versus food for wheat) and a different approach to grain trading giving more opportunities to mitigate mycotoxin problems by dilution in the corn market. The advent of transgenic corn and the logistical challenges of handling seed inventory led to a narrow genetic pool of widely adapted high-yielding hybrids, perhaps at the expense of some disease resistance.

Disruption of genes involved in butenolide and culmorin synthesis in Fusarium graminearum. D. T. SCHNEIDERMAN, S. P. MCCORMICK, N. J. ALEXANDER, A. JOHNSTON AND L. J. HARRIS. Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; and (S.P.M., N.J.A.) Mycotoxin Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, USA Department of Agriculture, Peoria, IL 61604, USA

Butenolide (4-acetamide-4-hydroxy-2-butenoic acid γ-lactone) and culmorin (a tricyclic sesquiterpene diol) are two less-studied mycotoxins produced by several Fusarium spp., including Fusarium graminearum Schwabe. A putative butenolide biosynthetic eight-gene cluster in F. graminearum includes fg08080 which encodes a zinc-finger protein and may function as a regulatory gene for the cluster. Gene disruption of fg08080 resulted in loss of butenolide biosynthesis and the downregulation of other genes within the cluster. Fusarium infection in wheat revealed no difference in virulence between the fg08080-disrupted and wild-type strains. fg08080 is required for butenolide biosynthesis in F. graminearum and may control butenolide biosynthesis through regulation of the gene cluster. A terpene synthase gene, fg10397, was observed to be induced under trichothecene-inducing conditions and during plant infection (based on EST library representation, Northern and microarray analysis). Transformed yeast cultures expressing FG10397 produced longiborneol, a terpene with the same tricyclic structure as culmorin, which was not produced by the progenitor yeast strain. The fg10397 gene was disrupted in F. graminearum strain 9F1, a wild-type strain that produces a significant amount of culmorin in vitro. No culmorin was produced by 9F1 strains with a disrupted fg10397 while wild-type and fg10397 add-back strains produced culmorin in liquid cultures. Thus, fg10397 encodes a longiborneol synthase that is required for culmorin synthesis.

Alternate route to attain resistance against Fusarium graminearum . R. SUBRAMANIAM, C. NASMITH, L. WANG AND W. LEUNG. Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Breeding programmes have yielded many tolerant varieties of wheat over the years against fusarium head blight (FHB). Although this line of defence against FHB will continue, it is imperative that we understand the underlying molecular mechanisms such that we can develop crop varieties that are durable in their resistance against FHB. Of the two types of resistance that are present in plants, resistance against Fusarium utilizes the ancient innate immunity pathway. This resistance pathway has evolved in plants to recognize the patterns or signatures of microorganisms in order to mount an effective response. In the long term, this type of response is also more durable. In order to gain insight into this pathway, our laboratory is involved in characterizing the patterns contained in Fusarium that will trigger the innate immunity pathway. A detailed characterization of one such pattern in the pathogen has allowed us to evoke the innate immunity pathway and provide resistance against FHB, even in the susceptible wheat ‘Roblin’.

Testing the WCORT oat entries for reaction to fusarium head blight. A. TEKAUZ AND J. M. FETCH. Cereal Research Centre, Agriculture and Agri-Food Canada, 195 Dafoe Road, Winnipeg MB R3T 2M9, Canada

The Western Cooperative Oat Registration Test (WCORT) is grown annually to evaluate advanced oat breeding lines for their agronomic, disease and quality attributes. This test supplies the data necessary for support by the ‘Prairie Recommending Committee for Oat and Barley’, and subsequent official registration by the Canadian Food Inspection Agency. Disease data generated include that for stem rust, crown rust, smut and BYDV. Information on fusarium head blight (FHB), now regarded as an important disease of oat in western Canada, has hitherto not been available or considered. The 36 entries in the 2008 WCORT were grown in the irrigated CRC FHB Nursery at Portage la Prairie MB, and exposed to ground-applied Fusarium graminearum Schwabe-infested corn kernel inoculum to assess their FHB reactions, based on levels of deoxynivalenol (DON) in the whole grain. A severe FHB epidemic ensued in 2008. DON levels ranged from 8.0 to 40.2 ppm; ‘Leggett’, a check cultivar, had the lowest DON. Preliminary resistance designations (MR or moderately resistant, etc.) were applied to the lines. Entries from individual breeding programmes were scattered in several resistance categories. These preliminary designations need to be verified or amended in 2009 and in future years, to provide valuable new information on overall oat cultivar performance for western Canada and beyond.

Preliminary observations on diversity in several fusarium head blight-causing Fusarium species from Manitoba, Ontario and Québec. A. TEKAUZ AND D. GABA. Cereal Research Centre, Agriculture and Agri-Food Canada, 195 Dafoe Road, Winnipeg MB R3T 2M9, Canada; and (D.G.) Grain Research Laboratory, Canadian Grain Commission, 1404-303 Main Street, Winnipeg MB R3C 3G8, Canada

Several Fusarium spp. are routinely isolated from seed of oat and barley crops affected by fusarium head blight (FHB). These species, F. avenaceum (Fr.) Sacc. (Fa), F. graminearum Schwabe (Fg), F. poae (Peck) Wollenw. (Fp) and F. sporotrichioides Sherb. (Fs), incite the disease in field trials or controlled environment settings on both oat and barley. Recent work shows that the population of Fg from wheat in Canada comprises two deoxynivalenol (DON) chemotypes, 3ADON and 15ADON, which can differ in their total DON production. It is not known whether the Canadian populations of the other species which cause FHB are physiologically uniform or diverse, or differ in their mycotoxin profiles. To assess their diversity, 20–29 isolates of each of Fa, Fg, Fp and Fs, obtained from three Canadian provinces, were cultured on agar media under uniform conditions to observe their rates of growth. Within each species colony growth varied significantly among isolates. Regional origin, more than the host source (wheat, oat or barley) of the isolate, influenced colony growth. A first test for trichothecene mycotoxins on single isolates from oat, grown on sterilized rice medium, indicated that Fa produced no toxin (moniliformin not assayed), Fg produced DON and 3ADON, Fp produced nivalenol, and Fs produced HT-2 and T2.

Interaction between Cochliobolus sativus and Fusarium graminearum on seed of barley. A. TEKAUZ AND E. MUELLER. Cereal Research Centre, Agriculture and Agri-Food Canada, 195 Dafoe Road, Winnipeg MB R3T 2M9, Canada

Cochliobolus sativus (Ito & Kurib.) Drechs.:Dastur and Fusarium graminearum Schwabe both are important pathogens of barley in Manitoba, and can often be isolated from the same seed. Their presence is indicative that spot blotch and/or fusarium head blight (FHB), respectively, affected the crop. The finding that C. sativus appeared to be inhibitory to F. graminearum and reduced the severity of FHB on barley spikes in a controlled environment prompted an examination of their isolation frequency from seed putatively infected by both species. Seed of the barley cvs. ‘Harrington’, ‘CDC Stratus’ and ‘Stander’, grown at two test locations in southern Manitoba, was plated onto PDA medium, PDA amended with Benlate^® (benomyl, to which C. sativus is insensitive), and PDA amended with PCNB (quintozene, to which Fusarium spp. are insensitive). Averaged over the three cultivars and two test sites, isolation frequencies of C. sativus and Fusarium spp. (mainly F. graminearum) on PDA, PDA + Benlate^®, and PDA + PCNB were 46.7 and 25.0, 64.7 and 0.3, and 3.8 and 36.3%, respectively. The results suggest that when both pathogens are present, their isolation frequency on a ‘neutral’ medium is reduced (here by 31% for Fusarium spp. and 22% for C. sativus) compared with when one or the other is absent, and is indicative of a mutually inhibitory effect.

Evaluation of oat germplasm for resistance to fusarium head blight. A. TEKAUZ, J. M. FETCH AND M. SAVARD. Cereal Research Centre, Agriculture and Agri-Food Canada (AAFC), 195 Dafoe Road, Winnipeg MB R3T 2M9, Canada; and (M.S.) Eastern Cereal and Oilseed Research Centre, AAFC, 960 Carling Avenue, Ottawa ON K1A 0C6, Canada

Fusarium head blight (FHB) is an important disease of cereals in western Canada. In oat FHB is difficult to recognize, and its presence and severity requires sampling of harvested grain for the causal Fusarium spp. and/or deoxynivalenol (DON), a mycotoxin associated with infection. The food and feed industries both require oat with a low content of DON. Differences in DON occur among registered Canadian oat cultivars, but better resistance to FHB is needed and may be available in exotic Avena germplasm. A selection of oat lines from various international gene banks has been evaluated at the irrigated CRC Portage la Praire FHB Disease Nursery for the past three years. In 2008, conditions for infection following artificial inoculation with Fusarium graminearum Schwabe were particularly favourable resulting in high levels of disease. DON measured 26–57 ppm in wheat and barley checks included in the nursery. Among 150 oat accessions tested, DON levels in the most susceptible tier of 25 averaged 29 ppm, with seed-borne F. graminearum as high as 76%. However, DON levels in the nine best lines were considerably lower, averaging 7.4 ppm, and were accompanied by relatively low F. graminearum (29% kernel infection). These low DON oat accessions are promising parents for use in crosses to breed for enhanced resistance to FHB.

Comparison of the fungicide sensitivity of Alberta and Prince Edward Island isolates of Fusarium graminearum producing either either 3- or 15-acetyl deoxynivalenol. T. K. TURKINGTON, R. CLEAR, J. GILBERT, T. NOWICKI, K. O'DONNELL, A. TEKAUZ, T. WARD, A. P. ROONEY, H. KLEIN-GEBBINCK AND R. A. MARTIN. Lacombe/Beaverlodge Research Centre, Agriculture and Agri-Food Canada (AAFC), Lacombe AB T4L 1W1, Canada; (J.G., A.T.) Cereal Research Centre, AAFC, 195 Dafoe Road, Winnipeg MB R3T 2M9, Canada; (R.C., T.N.) Grain Research Laboratory, Canadian Grain Commission, 1404-303 Main Street, Winnipeg MB R3C 3G8, Canada; (K.O., T.W., A.P.R.) USA Department of Agriculture, Peoria, IL 61604, USA; and (R.A.M.) Charlottetown Research Centre, AAFC, 440 University Avenue, Charlottetown, PE C1A 4N6, Canada

Fusarium graminearum Schwabe (Fg) of the ‘3ADON’ chemotype is now displacing ‘15ADON’ isolates in Canada. One concern regarding this shift in chemotypes is related to potential differences in fungicide sensitivity. This could have significant implications as fungicide application is an important strategy to reduce disease severity and mycotoxin contamination. Fungicide sensitivity was assessed for a total of 12 isolates of Fg; three 3ADON and three 15ADON from each of Alberta and Prince Edward Island. Spezieller Nährstoffarmer agar (SNA) plates were amended with 0, 0.78, 2.16, 4.16, 9.00, 16.78 and 30.62 μg mL⁻¹ of commercial grade tebuconazole. Plates were inoculated with mycelial plugs and after 72 h colony diameters were measured along two transects. Measurements were averaged for each plate, with results expressed as a percentage of the diameter of the unamended control. There were significant effects due to isolate, fungicide rate and their interaction. Contrasts indicated no significant differences due to chemotype, while there were significant linear, quadratic and cubic effects for mean response over fungicide concentrations. These preliminary results suggest that the 3ADON and 15ADON isolates tested had similar sensitivity to tebuconazole. Further research is investigating the potential of a microplate technique to assess fungicide sensitivity of Fg.

Incidence of Fusarium graminearum and Fusarium poae from a two-year wheat monitoring – factors that promote infection and mycotoxin contamination. S. VOGELGSANG, N. BISCHOFBERGER, F. WETTSTEIN AND H. R. FORRER. Research Station Agroscope Reckenholz-Taenikon ART, Reckenholzstrasse 191, 8046 Zurich, Switzerland

In a two-year investigation, wheat samples and respective information on cultivation techniques were collected from Swiss growers. Wheat kernels were examined for Fusarium spp. incidence and mycotoxin content. From a total of 248 samples originating from 16 out of 26 cantons, three Fusarium spp. were dominant: F. graminearum Schwabe, followed by F. poae (Peck) Wollenw. and F. avenaceum (Fr.) Sacc. The average deoxynivalenol (DON) content was 1.0 ppm and thus barely below the European limit for unprocessed cereals (1.25 ppm). With respect to pre-crop maize, conservation tillage or ploughing resulted in an average DON content of 3.2 ppm or 0.6 ppm, respectively. Recently, we started to measure the content of other trichothecenes and zearalenone (ZON). Preliminary data (92 samples) suggest that nivalenol (NIV) and ZON production are correlated to similar production factors (NIV: average of 39.1 and 10.2 ppb for the two cropping systems; ZON: 86.5 and 40.5 ppb). However, since no correlation was found between F. poae incidence and both the NIV content and the two cropping systems, we assume the presence of F. graminearum NIV chemotypes. Ongoing toxin measurements, chemotype investigations of fungal isolates as well as in-depth analyses of the cultivation data should contribute to elucidate factors that influence the occurrence and toxin contamination by the most prevalent Fusarium species on wheat.

Biocontrol and bioprotection fungi against fusarium head blight and mycotoxin accumulation in cereals . V. VUJANOVIC. Department of Food and Bioproduct Sciences, University of Saskatchewan, College of Agriculture and Bioresources, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada

In North America, fusarium head blight (FHB) causes severe yield losses in wheat and barley, thus greatly impacting Canadian agriculture. Saskatchewan prairies represent approximately 40% of the overall cultivated land in Canada and are one of the most important cereal crop regions worldwide. Fungi can counteract Fusarium spp. causing FHB and hence prevent the appearance of the disease and accumulation of associated mycotoxins (deoxynivalenol, nivalenol, and zearalenone). Optimal biocontrol seems to rest within Fusarium-specific mycoparasites, whereas bioprotection mostly depends on plant-specific endophytes of wheat and barley. The overall aim is the creation of a new generation of beneficial bioinoculants efficient against FHB. These are considered environmentally friendly or green solutions for feed and food safety, as well as economic profitability of cereal crops.

Biological management of fusarium head blight of wheat with Clonostachys rosea strain ACM941. A. G. XUE, H. D. VOLDENG, M. E. SAVARD, G. FEDAK AND Y. H. CHEN. Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Fusarium head blight (FHB), caused by Gibberella zeae (Schw.) Petch, is a harmful disease of wheat. A strain of Clonostachys rosea (Link:Fr.) Schroers, ACM941 (ATCC #74447) was evaluated for its ability to inhibit perithecial production of G. zeae and for the control of FHB and deoxynivalenol (DON) contamination under greenhouse and field conditions, in comparison to the registered fungicide Folicur^® (tebuconazole). ACM941 reduced G. zeae perithecial production by > 99% in a leaf disk assay and by > 60% under field conditions. In the greenhouse trials, ACM941 significantly reduced infected spikelets (IS) by 64% and Fusarium-damaged kernels (FDK) by 65%. Under simulated disease epidemic conditions during 2005–2007, ACM941 significantly reduced the FHB index by 58%, IS by 46%, FDK by 49% and deoxynivalenol (DON) in kernels by 21%. ACM941-CU, a formulated product of ACM941, was evaluated in two field trials in 2008. Over the average of the two trials, ACM941-CU reduced FHB index by 31.4%, FDK by 43.8% and DON by 37.1%. These effects were significant but less than those achieved by tebuconazole in the same trials, suggesting that ACM941 is a promising bioagent against G. zeae and may be used as a control measure in an integrated FHB management programme.

An overview of oat fusarium head blight in Canada. W. YAN. Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Studies on fusarium head blight (FHB) in oats are new and limited. This presentation provided an overview on the current activities related to oat FHB research and breeding in Canada under the following subtitles: (1) assessment of the FHB problem in oats, (2) identification of FHB-tolerant germplasm, (3) breeding for FHB tolerant genotypes, and (4) proposed genetic studies to facilitate marker-assisted selection. It is now clear that oats are not immune to FHB as previously believed. In fact, oats can be highly susceptible to FHB under excessive inoculation and inductive conditions, suggesting that FHB can be a potential problem for oat production. In natural conditions, the phototoxic level produced by FHB in oats is generally low, but in some areas in some years, the deoxynivalenol level, averaged across multiple genotypes, was higher than 3 ppm, presenting a real problem for the oat industry. There are inheritable differences in oats in FHB tolerance. Tolerant lines have been identified and used in breeding programmes. Some genetic studies on oat FHB have also been initiated, which may facilitate breeding from FHB-tolerant oat cultivars.

Cytogenetic analysis of an intergeneric amphiploid × triticale hybrid – a new source of resistance to fusarium head blight. Y. YANG, G. FEDAK, W. CAO, D. CHI, J. ZENG, A. XUE AND F. HAN. Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; (J.Z., Y.Y.) Triticeae Research Institute of Chengdu Science Academy, Sichuan Agricultural University, Wenjiang District, 611130, Sichuan, China; and (F.H.) Division of Biological Science, University of Missouri-Columbia, Columbia, 65211-7400, USA

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe, is a ravaging disease of cereal crops worldwide. The Thinopyrum spp. carry important traits such as biotic and abiotic stress tolerance. The amphiploid 8801 (AABBEE) with the E genome from Thinopyrum elongatum, derived from the hybrid Triticum turgidum (AABB)/Thinopyrum elongatum (EE), is an excellent source of FHB resistance. We produced a hybrid between the amphiploid 8801 and the triticale line T182 (AABBRR). In this study, 29 F₃ plants were analyzed by genomic in situ hybridization. The chromosome numbers of the plants ranged from 28 to 45. The results showed that one plant with 42 chromosomes and one plant with 45 chromosomes each contained a pair of E/R Robertsonian translocation chromosomes and one E/R translocation chromosome was also found in each of five additional F₃ plants. Among these five plants, there was a unique plant with 28 chromosomes which contains an E/R chromosome translocation. One R genome chromosome and seven E genome chromosomes were also found in three F₃ plants with 35 chromosomes. Meiotic studies are being conducted on the above materials and their progenies.

A new source of resistance to fusarium head blight from wheat – Elymus repens introgressions. J. ZENG, W. CAO, G. FEDAK, P. HUCL, Y. YANG, A. XUE AND D. CHI. Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada; (J.Z., Y.Y.) Triticeae Research Institute of Chengdu Science Academy, Sichuan Agricultural University, Wenjiang District 611130, Sichuan, China; and (P.H.) Department of Plant Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada

Elymus repens (L.) Gould (2n = 6× = 42, StStStStHH) is a hexaploid wild grass species, distantly related to wheat (Triticum aestivum L. em Thell; 2n = 6× =42, AABBDD). It has a high level of resistance to fusarium head blight (FHB). We have transferred genes for resistance to FHB from E. repens to common bread wheat. The cross Crocus/E. repens was made at the Crop Development Center, Department of Plant Sciences, University of Saskatchewan. The F₁ plants were backcrossed to Crocus, then seeds from the BC₁F₁plants were bulked and advanced to the BC₁F₇generation. Sixteen lines were selected and evaluated for FHB reaction. Two lines, P1142 and P1131 (F₈), were re-selected based on agronomic traits and FHB resistance performance. The results showed that the line P1142 was still segregating, with chromosome numbers ranging from 42 to 56, while the line P1131 with 56 chromosomes was stable morphologically. Cytological study and in situ hybridization analyses indicated that we obtained several wheat–E. repens addition and translocation lines, and two partial amphiploids. The results of greenhouse FHB evaluation by point inoculation showed that all the lines had a high level of resistance to FHB with only one spikelet infected (6%), compared with the check ‘Roblin’ (100%) and the parent Crocus (85%).

Diversity and density of fungal and bacterial populations in wheat rhizosphere under monoculture and rotation cropping systems. D. ZHAO, Y. XU, G. ZHOU, B. L. MA, M. LIN, H. QU, L. CHUN, F. YANG, Y. FU AND Y. ZHANG. Horticultural Branch, Heilongjiang Academy of Agricultural Sciences, 666 Haping Road, Harbin, Heilongjiang, 150069, China; (Y.X., M.L., H.Q., F.Y. Y.F., Y.Z.) Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, 138 Haping Road, Harbin, Heilongjiang, 150081, China; and (G.Z., B.L.M.) Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, 960 Carling Avenue, Ottawa, ON K1A 0C6, Canada

Soil fungi and bacteria are major components of rhizosphere environment and important factors affecting crop growth. A field study was conducted to determine the diversity and density of fungi and bacteria in wheat rhizosphere in the wheat monoculture and wheat-corn-soybean rotation cropping systems. Soil samples were collected at seedling, jointing, flowering and ripening growth stages of wheat. The fungal population density was higher in wheat monoculture than in the rotation system at all growth stages, but the difference was significant (P < 0.05) only for the flowering stage. The fungal population density increased for both cropping systems during the first three stages, and decreased during the ripening stage. Both the diversity and the population density of bacteria were higher in wheat monoculture than in wheat rotation for all four growth stages, but the differences were significant (P < 0.05) for only the jointing and ripening stages. Bacterial population showed a single peak at the wheat flowering stage for both cropping systems. Our data suggested that the dynamics of fungi and bacteria in wheat rhizosphere might affect the resistance of wheat crop to fusarium head blight and other diseases, and the importance of further investigating the relationship between rhizosphere microorganism and disease incidence and yield formation.

Notes

^†This meeting was held in Ottawa, Ontario on 1–4 November 2009.