Fusarium Species Associated with Spikes and Grains of Cereal Crops in the Volga Region: Virulence and Toxin-Producing Potential

Fusarium head blight (FHB) is a major threat to cereal crops, causing yield losses and mycotoxin contamination. This study investigated <i>Fusarium</i> species associated with spikes and grains of cereals in the Volga region, focusing on species diversity, virulence, and mycotoxin production. <i>F. sporotrichioides</i>, <i>F. avenaceum</i>, and <i>F. poae</i> were the most prevalent species isolated from wheat, rye, barley, triticale, and stored grains in the Volga region. Individual strains of <i>F. culmorum</i> and <i>F. graminearum</i> were also identified. High intraspecific variability in virulence was observed for the first time within <i>F. sporotrichioides</i> and <i>F. poae</i> species, and highly virulent strains were identified for the first time within these species. Not only symptomatic but also asymptomatic (weakly expressed) infections caused by <i>F. sporotrichioides</i> were shown to be associated with the accumulation of high levels of T-2 toxin in the grains of infected plants. <i>F. sporotrichioides</i> strains were first demonstrated to exhibit intraspecific variability in zearalenone-producing potential. A <i>F. graminearum</i> strain possessing the nivalenol chemotype was first identified in Russia. The study highlights the diversity of the regional FHB pathocomplex and the risks it poses to grain safety.