Insights into the Species Diversity and Features of Fungi in the Fusarium heterosporum Species Complex

In this study, four Fusarium strains isolated from Poaceae plants infected by Claviceps spp. and one strain isolated from the stem of Cirsium arvense collected from two regions of Russia that are separated by a long distance were analyzed in detail. These fungi were accurately identified through a phylogenetic analysis of the fragments of translation elongation factor 1-α and RNA polymerase second largest subunit loci. Four of them belong to F. heterosporum species, and one strain, MFG 13060, together with the historical reference strain BBA 62226, forms a distinct lineage within the F. heterosporum species complex (FHSC). The morphological features of the anamorph structures of the fungi within the FHSC are presented. All the analyzed F. heterosporum strains are heterothallic and require a partner to mate. The fertile perithecia of F. heterosporum were obtained in a crossing experiment, and the teleomorph structures were characterized in detail. The screening of 19 mycotoxins typically produced by Fusarium fungi using high-performance liquid chromatography with tandem mass spectrometry revealed the ability of the strains to produce only moniliformin on an autoclaved rice substrate. A reassessment of the species diversity, distribution, and significance of fungi belonging to the FHSC is necessary to elucidate the unclear relationships between F. heterosporum, Claviceps fungi, and cereal plants.