Taxonomic Delineation of Fusarium weifangense within the F. incarnatum-equiseti Species Complex

Modern delineation of the Fusarium species using genetic data faces challenges no less complex than those previously encountered, when species descriptions were based exclusively on morphological characteristics. In present study, the taxonomic status of five fungal strains belonging to the F. incarnatum-equiseti species complex, which is a highly heterogeneous group of Fusarium, was clarified. The strains were isolated from wild and cultivated grasses and maintained in the fungal collections for 13-18 years under the epithet F. semitectum (syn. F. incarnatum). More precise identification of these strains as F. weifangense was achieved by combining phylogenetic analysis of fragments of the translation elongation factor 1α gene, the gene encoding RNA polymerase subunit II analyses, and calmodulin gene with morphological description and pathogenicity evaluation. The results of a comparative analysis of the phenotypic characteristics of the strains with those previously reported for this species, which are largely inconsistent. That differences in morphological description may be due to internal polymorphism of taxon, as well as differences in methodological approaches used by different research groups. The analyzed strains caused weak necrosis of wheat leaves inoculated under laboratory conditions, which indicates that F. weifangense is a non-pathogenic fungus. However, the previously demonstrated ability of the F. weifangense strains to produce zearalenone and diacetoxyscirpenol makes it necessary to clarify area and adaptive properties of this fungus.