Fusarium algeriense, sp. nov., a novel toxigenic crown rot pathogen of durum wheat from Algeria is nested in the Fusarium burgessii species complex

ABSTRACT

A novel crown rot pathogen of wheat discovered during pathogen surveys in Algeria in 2014 and 2015 is formally described as Fusarium algeriense. Multilocus molecular phylogenetic data resolved the eight isolates of this pathogen as a genealogically exclusive species lineage in the F. burgessii species complex. The previously described species of this complex, F. burgessii and F. beomiforme, produce abundant chlamydospores in culture, and their optimal temperature for growth is 30 C. In comparison, F. algeriense did not produce chlamydospores under the conditions tested and its optimal temperature for growth is 25 C. Furthermore, F. algeriense differs from F. burgessii because it does not produce polyphialides and F. beomiforme, because it does not produce globose-to-napiform conidia in the aerial mycelium. Isolates of F. algeriense induced moderate crown rot on the susceptible spring wheat cultivar Norm in a temperature-controlled incubator. Fusarium burgessii and F. beomiforme, in contrast, only induced mild symptoms of this disease. BLASTn searches of the whole-genome sequence of F. algeriense strains NRRL 66647 and 66648, using homologs of genes that are responsible for synthesis of toxic secondary metabolites, indicated that they have the potential to produce several polyketide and non-ribosomal peptide-derived mycotoxins. However, moniliformin and 2-AOD-ol (2-amino-14,16-dimethyloctadecan-3-ol) were the only mycotoxins detected by liquid chromatography–mass spectrometry (LC-MS) analyses of strains cultivated in vitro on a solid medium. A polymerase chain reaction (PCR) assay for MAT idiomorph revealed that MAT1-1 and MAT1-2 strains of F. algeriense were present in Algeria, which suggests this pathogen might possess a heterothallic sexual reproductive mode.

KEYWORDS:

• Mating type
• molecular phylogenetic
• moniliformin
• morphology
• mycotoxins
• pathogenicity
• phylogenetic species recognition
• qPCR
• 1 new taxon

ACKNOWLEDGMENTS

The authors thank Gail Doehring, Jennifer Teresi, Debbie Shane, Nathane Orwig, Amy McGovern, and Arthur Thompson for skilled technical assistance in various aspects of this study.

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Funding

Imane Laraba thanks the Ministry of Higher Education and Scientific Research and École Nationale Supérieure Agronomique, Algiers, Algeria, for support while conducting research at the National Center for Agricultural Utilization Research, Peoria, Illinois.