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Alternaria infectoria species-group member emerges as a wheat pathogen in New York

Michael Fulcher: Cornell University

<div>A recently observed foliar disease of wheat was attributed to isolates from the <em>Alternaria infectoria</em> species-group. This globally distributed species complex contains pathogens and saprobes associated with a variety of host plants, and members of the group exhibiting both of these lifestyles are known to inhabit wheat. We scouted cereal fields in New York for this fungus and recovered it from symptomatic and asymptomatic gramineous hosts, including non-cultivated species. Isolates showed variable pathogenicity on several hosts in greenhouse and laboratory assays. Our wheat pathogenic strains were not identified as a known species based on morphology or a multi-gene phylogeny, and pathogenicity on wheat could not be predicted without plant-based assays. The difficulty of identifying species and distinguishing pathogen from non-pathogen in this group is a challenge for disease monitoring. We are employing comparative genomics to study species delimitation within the entire <em>A. infectoria </em>complex and to search for genetic factors that underlie pathogenicity.</div>