Isolation, Toxigenic Potential, and Mating Type of Fusarium pseudograminearum Causing Wheat Crown Rot in Hebei, China

Fusarium crown rot (FCR) is a devastating fungal disease of wheat in China that causes substantial yield losses and deterioration of grain quality. To clarify the pathogen composition and associated mycotoxin risks of FCR in Hebei Province, a comprehensive field survey was conducted during the critical growth stage from flowering to maturity (April to May) of the 2024 wheat season from 46 sites. Fungal isolates were obtained from symptomatic wheat stem bases and were identified through morphological and molecular analyses. In total, 156 <i>Fusarium</i> isolates were obtained, and from these isolates, 12 <i>Fusarium</i> species were identified based on species-specific PCR and DNA sequencing of the <i>translation elongation factor 1-α</i> (<i>TEF1</i>) loci. Of these <i>Fusarium</i> isolates, 118 were identified as <i>Fusarium pseudograminearum</i>, 16 identified as <i>F. graminearum</i> and the remaining isolates consisted of <i>F. acuminatum</i>, <i>F. asiaticum</i>, <i>F. boothii</i>, <i>F. culmorum</i>, <i>F. equiseti</i>, <i>F. flocciferum</i>, <i>F. incarnatum</i>, <i>F. proliferatum</i>, <i>F. sinensis</i>, and <i>F. verticillioides</i>. The results revealed that <i>F. pseudograminearum</i> with the 15ADON genotype was the predominant species, accounting for 75.64% of all the isolates, followed by <i>F. graminearum</i>. Trichothecene genotyping revealed that 91.53% of the <i>F. pseudograminearum</i> strains possessed the 15ADON genotype (108 isolates), while 8.47% exhibited the 3ADON genotype (10 isolates). Although differences were observed within <i>F. pseudograminearum</i> in <i>MAT1-1</i> and <i>MAT1-2</i> distributions among different sampling regions, a well-balanced mating type ratio was identified across Hebei Province. Population genetic analysis based on composite genotypes (trichothecene and mating type) revealed moderate to high genetic diversity within the <i>F. pseudograminearum</i> population. Recent studies on causal <i>Fusarium</i> species, trichothecene genotypes, and their distribution in China are compared and discussed. These findings may have implications in managing this significant fungal disease.