A novel Asian clade within the Fusarium graminearum species complex includes a newly discovered cereal head blight pathogen from the Russian Far East

We investigated Fusarium. graminearum complex (Fg complex) species diversity and toxin potential in European and Asian regions of the Russian Federation and adjoining regions northwest to Finland and South near Harbin, Heilongjiang Province, China, to expand our knowledge of tire host range and geographic distribution of these economically devastating cereal head blight pathogens. Results of a recently described multilocus genotyping (MLGT) assay revealed that F. graminearum was the sole Fg complex pathogen in northern Europe and the predominant one in Asia (90.5%). Even though isolates of E graminearum were segregating for 3-acetyldeoxynivalenol (3ADON) and 15-acetyldeoxynivalenol (15ADON) chemotype in nearly equal frequencies in the regions sampled oil both continents, significant differences in the geographic distribution of isolates producing these acetyl ester derivatives of deoxynivalenol (DON) were observed in Europe. While 93.5% of the isolates in southern Russia (it 43 of 46) possessed the 15ADON chemotype, isolates of F. graminearum recovered in Finland and northwestern Russia (n = 40) were exclusively M-DON producers. Based on results Of the MLGT assay, species identity of 10 genetically novel F complex isolates front the Russian Far East was investigated further via molecular phylogenetic analyses Of analyses DNA sequence data. Results of these analyses resolved these isolates as a phylogenetically, distinct, reciprocally monophyletic sister lineage of F. asiaticum, which together with F. vorosii form a newly discovered Asian clade within the Fg complex. Because this novel lineage fulfills the highly conservative criterion of genealogical exclusivity under phylogenetic species recognition it is formally described herein as E ussurianum. In addition to morphologically characterizing isolates of F ussurianum, experiments were conducted to assess pathogenicity to wheat and trichothecene toxin potential in planta.