Pathogenic diversity in Pyrenophora teres f. maculata (spot form net blotch of barley) populations from the Canadian Prairies. A. AKHAVAN, T. K. TURKINGTON, H. ASKARIAN, A. TEKAUZ, K. XI, H. R. KUTCHER, J. R. TUCKER, C. KIRKHAM, K. KUMAR AND S. E. STRELKOV. Department of Agricultural, Food and Nutritional Science, 410 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada; (T.K.T.) Lacombe Research Centre, Agriculture and Agri-Food Canada (AAFC), 6000C & E Trail, Lacombe, AB T4L 1W1, Canada; (A.T.) Cereal Research Centre, AAFC, 195 Dafoe Road, Winnipeg, MB R3T 2M9, Canada; (K.X., K.K.) Field Crop Development Centre, Alberta Agriculture and Rural Development, 6000C & E Trail, 51 Campus Drive, Lacombe, AB T4L 1W1, Canada; (H.R.K.) Crop Development Centre, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada; (J.R.T.) Brandon Research Centre, AAFC, 2701 Grand Valley Road, Brandon, MB R7A 5Y3, Canada; and (C.K.) Melfort Research Farm, AAFC, P.O. Box 1240, Melfort, SK S0E 1A0, Canada
Cluster analysis using microsatellite DNA markers was performed on a collection of 82 Pyrenophora teres Drechs. f. maculata Smedeg. isolates from the Canadian Prairies. Twenty-seven of these isolates were selected as representatives of different clades to assess pathogenic variation among them. The isolates were evaluated against seedlings of 11 barley differentials, and leaves of each plant were rated on a 1–9 scale, with plants rated 1–3 and >3 scored as resistant and susceptible, respectively. Cluster analysis revealed 13 pathotype groups among the 27 representative isolates. Two pathotype groups, which comprised 52% of the isolates, were found to be predominant in the collection. Variation in virulence ranged from that of a Manitoba isolate (MBV25) which was virulent on 10 of the 11 differentials with an average disease rating of 6.1, to an avirulent isolate from Alberta (AB57) with an average rating of 2.2. Among the genotypes tested, ‘Herta’ was the most susceptible with an average disease rating of almost 5.9. In contrast, the differential CI 9214 was resistant to all isolates, except two, with average rating scores of 2.8. Thus, the differential line CI 9214 and breeding material derived from it can be considered as potential sources of spot form net blotch resistance for Canadian Prairie barley breeding programmes.
Pathotype shift in a population of Pyrenophora teres f. teres (net form net blotch of barley) from the Canadian Prairies. A. AKHAVAN, T. K. TURKINGTON, H. ASKARIAN, A. TEKAUZ, K. XI, H. R. KUTCHER, J. R. TUCKER, C. KIRKHAM, K. KUMAR AND S. E. STRELKOV. Department of Agricultural, Food and Nutritional Science, 410 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada; (T.K.T.) Lacombe Research Centre, Agriculture and Agri-Food Canada (AAFC), 6000C & E Trail, Lacombe, AB T4L 1W1, Canada; (A.T.) Cereal Research Centre, AAFC, 195 Dafoe Road, Winnipeg, MB R3T 2M9, Canada; (K.X., K.K.) Field Crop Development Centre, Alberta Agriculture and Rural Development, 6000C & E Trail, 51 Campus Drive, Lacombe, AB T4L 1W1, Canada; (H.R.K.) Crop Development Centre, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada; (J.R.T.) Brandon Research Centre, AAFC, 2701 Grand Valley Road, Brandon, MB R7A 5Y3, Canada; and (C.K.) Melfort Research Farm, AAFC, P.O. Box 1240, Melfort, SK S0E 1A0, Canada
Thirty-nine representative isolates of Pyrenophora teres Drechs. f. teres Smedeg. from the Canadian Prairies were evaluated for virulence on nine barley differentials. One week following inoculation, the second and third leaves of each plant were rated on a 1–10 severity scale, with plants rated as 1–5 and >5 scored as resistant and susceptible, respectively. Isolates were grouped based on the relative number of resistant (r) and susceptible (s) differential reactions. These groups ranged from 9r/0s, designated as group A, to 1r/8s, designated as group I. Each isolate was further designated with a number (1–11) based on the specific susceptible or resistant reactions on each of the nine barley genotypes. Cluster analysis revealed 16 pathotype groups among the 39 isolates. Two pathotype groups, which comprised 44% of the isolates, were found to be predominant in the collection, while 10 isolates (26%) had distinct virulence profiles. Comparison of the results from an earlier study in the 1980s suggests the virulence profile of P. teres f. teres on the Prairies has changed in the last three decades. Seven new pathotypes also were identified for the first time in the P. teres f. teres population from the Canadian Prairies.
Pathogenic fungi associated with root rot of field pea on the Canadian prairies. A. ESMAEILI TAHERI, S. SAFARIESKANDARI, S. CHATTERTON, N. FOROUD, B. D. GOSSEN AND D. L. MCLAREN. Lethbridge Research Centre, Agriculture and Agri-Food Canada (AAFC), 5403 1st Avenue South, Lethbridge, AB T1J 4B1, Canada; (B.D.G.) Saskatoon Research Centre, AAFC, 107 Science Place, Saskatoon, SK S7N 0X2, Canada; and (D.L.M.) Brandon Research Centre, AAFC, 2701 Grand Valley Road, Brandon, MB R7A 5Y3, Canada
Root rot of field pea (Pisum sativum L.) is a major production constraint on the Canadian prairies. Symptomatic plants were sampled from 10 fields in 2014; four in Alberta, three in Saskatchewan and three in Manitoba. Fungi associated with symptomatic roots, crowns and lower stem tissues of pea were characterized using plate culture and PCR-based identification. Tissue segments were surface sterilized and incubated on PDA. Fungal isolates were identified according to morphology, and TEF-1 alpha or ITS sequences. Fusarium spp. accounted for more than 60% of total isolations. Fungi associated with roots and crowns were similar, but differed significantly from the pathogen communities invading lower stems. The Mycosphaerella/Ascochyta complex and Alternaria spp. were the most abundant pathogens in lower stems. Fusarium avenaceum (Fr.) Sacc. was predominant in crowns, but in roots Fusarium redolens Wollenw. and F. avenaceum were most frequently isolated. Aphanomyces euteiches Drechs. was only detected using PCR, indicating that identification using plate culture systematically under-estimates the importance of this pathogen. The composition of Fusarium spp. on roots from healthy and diseased patches of affected fields in Alberta was also evaluated. There were differences in the proportions of Fusarium spp. detected in roots from diseased and healthy patches. Similarly, pea seedlings grown in soil from diseased areas developed severe root rot in a greenhouse bioassay, while those grown in healthy soil did not. Use of DNA quantification to determine levels of predominant pathogens causing root rot of field pea in the prairie region is clearly required.
Monitoring of the Puccinia striiformis population in central Alberta by examining the pathogen’s intergenic spacer region. M. D. HOLTZ, K. KUMAR, K. XI AND T. K. TURKINGTON. Field Crop Development Centre, Alberta Agriculture and Rural Development, 6000C & E Trail, Lacombe, AB T4L 1W1, Canada; and (T.K.T.) Lacombe Research Centre, Agriculture and Agri-Food Canada, 6000C & E Trail, Lacombe, AB T4L 1W1, Canada
Stripe rust, caused by Puccinia striiformis Westend., is an important and frequently occurring disease of cereals. There are different formae speciales of the pathogen; P. striiformis f. sp. tritici (Pst) and P. striiformis f. sp. hordei (Psh) are specialized on wheat and barley, respectively. The occurrence of the pathogen on different host species was monitored by examining length polymorphisms in the pathogen’s ribosomal DNA intergenic spacer 1 (IGS1) region, which facilitates identifying the pathogen to the formae specialis level and below. A total of 890 infected leaves were collected from wheat, triticale, barley and foxtail barley in 2013 and 2014 for PCR analysis. The expected host specificity of the formae speciales was confirmed on cultivated crops, but not on foxtail barley. The vast majority of infections on wheat were attributable to Pst, with the IGS1 genotype that was prevalent in previous years remaining dominant. Only Pst was found on triticale. Barley was predominantly infected by Psh, but 3% and 22% of infections appeared to be Pst in 2013 and 2014, respectively. The majority of these infections were from highly susceptible barley breeding material planted in close proximity to wheat. Foxtail barley was infected by Pst and Psh at an equal frequency. Unlike Pst, there was a significant change in the predominant Psh IGS1 genotype between 2013 and 2014. Several previously undetected IGS1 genotypes were found, with the majority occurring on barley or foxtail barley. This indicates that there are rare members of the pathogen population that have not yet been characterized.
Use of Fourier transform-infrared spectroscopy as a new method to study host resistance mechanism to fusarium head blight [Fusarium graminearum]. R. LAHLALI, L. WANG, S. KUMAR, C. KARUNAKARAN, P. R. FOBERT, G. PENG AND E. HALLIN. Canadian Light Source, 44 Innovation Boulevard, Saskatoon, SK S7N 2V3, Canada; (L.W., P.R.F.) National Research Council Canada, 110 Gymnasium Place, Saskatoon, SK S7N 0W9, Canada; and (G.P.) Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N OX2, Canada
Fusarium head blight (FHB) is a serious disease of wheat worldwide. Cultivar resistance to FHB depends on biochemical factors that confine the pathogen spread in spikes. In the current study, Fourier transform infrared (FTIR) spectroscopy (4000–800 cm−1) was used of bulk samples of florets and rachises to better understand the mechanism of FHB resistance. Three cultivars, resistant (‘Sumai3’), moderately resistant (‘FL62R1’) and susceptible (‘Muchmore’) to FHB, were compared. Changes in absorption spectra following inoculation were observed mostly between 3400–800 cm−1, and this range of FTIR spectra was analysed using integrated area of absorption bands to identify differences among the cultivars, and between diseased and healthy florets and rachises. Marked differences were observed in association with amide I, aromatic, carbonyl ester, phosphate, CH2 and functional groups between infected and non-infected spikes. In the rachis of resistant ‘Sumai3’, the bands of 1460 cm−1, 1650 cm−1 and 1615–1590 cm−1 representing CH2, amide I and aromatics, respectively, were persistent after infection at 4 and 10 days post-inoculation compared with those from the other two cultivars. These bands may be candidate biochemical markers for FHB resistance. The presence of these bands was more consistent in the rachis than in floret. The histological comparison of rachis showed many differences in the cell wall of the wheat cultivars before and after infection. It is concluded that FTIR spectroscopy can be a useful method in understanding the biochemical modes of action to FHB based on metabolic changes.
Managing crown rust in oat with fungicides and cultivar resistance. J. LIU, J. TAYLOR, C. KIRKHAM, G. PENG AND H. R. KUTCHER. Department of Plant Sciences, College of Agriculture and Bioresources, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada; and (C.K., G.P.) Melfort Research Centre, Agriculture and Agri-food Canada, Box 1240, Melfort, SK S0E 1A0, Canada
Crown rust, caused by the basidiomycete fungus Puccinia coronata Corda/Eriks., is an important oat disease. Our objectives were to assess the effect of fungicides and oat cultivars with varying resistance on yield and quality. Trials were conducted at Saskatoon and Melfort, SK in 2012 and 2013 using the cultivars ‘AC Morgan’ (susceptible), ‘CDC Dancer’ (moderately resistant) and ‘CDC Morrison’ (resistant). The fungicides propiconazole (Bumper®) and pyraclostrobin (Headline®) were applied at 209 and 100 g a.i. ha−1, respectively, at the flag leaf stage. In a separate experiment, ActigardTM was applied at 8.75 and 26.25 g a.i. ha−1, respectively, to ‘CDC Dancer’ and ‘CDC Morrison’ at seedling, boot and heading stage. At Saskatoon, severe crown rust infection was observed every year on ‘CDC Dancer’ and ‘AC Morgan’, but ‘CDC Morrison’ was generally free of the disease. At Melfort, only leaf-spot diseases occurred, and the levels were low at both locations (2–8% severity) each year. At Saskatoon, fungicides reduced crown rust severity by 14–57%, on ‘AC Morgan’ and ‘CDC Dancer’, and increased yield of ‘AC Morgan’ by 27–87% and ‘CDC Dancer’ by 0–20% depending on the year. There was little to no yield or quality response to fungicide on ‘CDC Morrison’. At Melfort, there was no substantial benefit of fungicide application on any cultivar and at none of the site-years was there an effect of fungicide on the quality of oat, including β-glucan, protein or total dietary fibre content. No effects of Actigard were observed on any of the yield/quality parameters measured.
Genetic and pathogenic variability of Sclerotinia sclerotiorum from canola in western Canada. K. PURI, H. GARG, J. DURKIN, D. D. HEGEDUS, M. HARRINGTON, J. ADAM, D. LIABEUF, K. GALI, A. SHARPE AND L. BUCHWALDT. Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada; and (K.G., A.S.) National Research Council, 110 Gymnasium Place, Saskatoon, SK S7N 0W9, Canada
Our objective was to characterize genetic and pathogenic variability of Sclerotinia sclerotiorum (Lib. de Bary) in western Canada, and examine if partial resistance in Brassica napus L. germplasm is effective against the pathogen population. In 2010, a single isolate was selected from each of 129 canola fields in Alberta, Saskatchewan and Manitoba. Genomic DNA was screened with 47 simple sequence repeat markers designed from the S. sclerotiorum genome sequence (Broad Institute). Genetic analyses were based on polymorphisms at 446 alleles. Test for genetic dissimilarity showed all isolates were unique haplotypes, which could be divided into 17 sub-populations using neighbour-joining analysis (NtSYS). Population structure was not related to geographic origin of isolates (Structure). One isolate from each sub-population was selected for a pathogenicity test on six B. napus lines. Plants grown in a semi-field nursery were inoculated at full flower by attaching a mycelium plug to the main stem with Parafilm. Lesion lengths were measured three times at weekly intervals for calculation of the area under the disease progress curve (AUDPC). Analysis of variance showed pathogenicity of isolates was significantly different with AUPDC ranging from 15.0 to 100.3 across lines. Germplasm line PAK54 had the highest level of resistance against all isolates (AUDPC 11.4–74.2) followed by PAK93 and K22, then DC21 and Tanto, while Topas was highly susceptible. The level of resistance in PAK54 and PAK93 from Pakistan is effective against the majority of the pathogen population in western Canada. Molecular markers are currently used to transfer loci conferring sclerotinia resistance into canola breeding lines.
Best management practices for stripe rust of wheat in Saskatchewan. J. T. VERA, J. LIU AND H. R. KUTCHER. Crop Development Centre, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada
Stripe rust of wheat (Puccinnia striiformis Westend. f. sp. tritici Eriks.) is observed every year in Saskatchewan. Our objectives were to determine: the benefit of fungicide to reduce disease and improve yield and quality of wheat cultivars varying in stripe rust resistance; the appropriate fungicide timing; and the effect of seeding date on application timing. The study was conducted at two locations in replicated, disease-inoculated, field experiments on susceptible (S), moderately resistant (MR) and resistant (R) cultivars, at two seeding dates: early (mid-May) and late (early June) in 2014. Tebuconazole (Folicur® 250EW) was applied at 125 g a.i. ha−1 at stem elongation, flowering (anthers visible on majority of spikes), early milk and at all three stages. Stripe rust was severe (73–98% of flag and penultimate leaves affected by symptoms) on the unsprayed check of the S cultivar at both locations and seeding dates. There were few stripe rust pustules detected on the R cultivar and no benefit to fungicide. In the early seeded experiment, fungicide applied at flowering was the most effective timing, reducing severity of the S cultivar to 54–72% and increasing yield by 116–354% and severity of the MR to 26–31% and increasing yield by 143–171%. In the late seeded experiment, optimum disease control was achieved at stem elongation. For the S cultivar, symptoms were reduced to 21–43% and yield increased by 21–77% and on the MR to 6–15% and by 9–12%, respectively. Three fungicide applications did not generally improve disease control over one well-timed application. Improved disease control through fungicide application resulted in higher yields for susceptible and moderate resistant cultivars.
Verified molecular markers linked to resistance or susceptibility to barley leaf scald disease [Rhynchosporium secalis] in spring barley. J. L. ZANTINGE, S. XUE AND P. E. JUSKIW. Field Crop Development Centre, Alberta Agriculture and Rural Development, 5030-50th Street, Lacombe, AB T4L 1W8, Canada
Barley leaf scald, caused by Rhynchosporium secalis J.J. Davis, is prevalent in central Alberta and reduces both barley yield and quality. In order to identify molecular markers that could be used for marker assisted selection (MAS) within our two-row malt spring barley breeding programme, we screened over 100 SSR or STS markers on scald resistant parental variety ‘Seebe’ and susceptible ‘Merit’. We then used these polymorphic markers to genotype 94 recombinant inbred lines (RILs) from a two-row malt barley breeding population J04075 with ‘Seebe’ parentage. This population was also assessed for scald resistance in the field with natural infection in Lacombe in 2009. QTL analysis was performed with WinQTLCart2.5 utilizing single-marker analysis (SMA), multiple interval mapping (MIM) and Mapdisto 1.7.0. Five molecular markers showed linkage to scald disease severity and each accounted for 4.76% to 10.4% of disease severity variations in the population. Marker CDO395 could be linked to one QTL on 3H, and Bmac0187 and GMS27b could be linked to one QTL on 7H as their mapping distance was 18.7 cM, whereas GBM1456 and Bmag1089 appeared to be linked to another QTL on 7H as their mapping distance was 4 cM. These markers were further tested on a few breeding populations in 2014. Reduced scald severity were revealed with the following four markers: up to 20.45% for CDO395, 25.6% for Bmac0187, 9.25% for GMS27b and 13.85% for GBM1456. Only Bmag1089 accounted for 30.5% of increased scald severity.
Developing near-isogenic Brassica napus lines for resistance to clubroot through introgression of resistance genes from B. rapa. Y. ZHANG, G. PENG, B. GOSSEN, S. VAIL, S. E. STRELKOV, S. F. HWANG AND F. YU. Saskatoon Research Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N OX2, Canada; (S.E.S.) Department of Agricultural, Food and Nutritional Science, 410 Agriculture/Forestry Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada; and (S.F.H.) Crop Diversification Centre North, Alberta Agriculture and Rural Development, 17 507 Fort Road N.W., Edmonton, AB T5Y 6H3, Canada
Development of a set of near-isogenic spring-type canola (B. napus L.) lines containing single clubroot resistance genes is urgently required. The lines could be used for differentiating the pathotypes of Plasmodiophora brassicae Woronin, monitoring race changes in the pathogen populations in canola fields, and pyramiding resistance genes. Genetic mapping has identified 10 genes for clubroot resistance that occur in B. rapa lines ECD01, ECD02, ‘Debra’, ‘Flower Nabana’, ‘Jazz Napa Cabbage’, ‘Milan White’ and ‘Siloga’. All the donor cultivars were highly resistant to pathotype 3 of P. brassicae and the first four were confirmed to be highly resistant to all other pathotypes found in Canada (2, 5, 6 and 8). Interspecific crosses were performed between canola line DH16516 and the respective resistance donors, and successive backcrosses are being carried out using DH16516 as a recurrent parent. The F1 or BC1 seed was obtained from all of the interspecific crosses except ‘Debra’. Gene-specific SNP markers associated with genes CRa in ECD02, CRb in ECD01, Rcr1 in ‘Flower Nabana’ and Rcr2 in ‘Jazz Napa Cabbage’ were identified and the resistance genes are being introgressed using these markers. Development of SNP markers linked to CRk and CRc in ‘Debra’, Crr3 in ‘Milan White’ and Crr1, Crr2 and Crr4 in ‘Siloga’ is in progress. A BC2 line carrying Rcr1 introgressed with limited donor background and a full set of C-genome chromosome was produced. This line and the gene-specific SNP markers are available for introgression of Rcr1 into breeding lines.