Species Composition and Trichothecene Genotyping of the Fusarium graminearum Species Complex from Wheat Show a Gradient Decline of 3ADON Genotype in Hubei, China

Members of the Fusarium graminearum species complex (FGSC) are the main causal agents of Fusarium head blight (FHB) of wheat and are frequently reported in the Yangtze River Basin of China. The present study examined the species composition and trichothecene genotypes of the FGSC in Hubei Province during 2024. Among the 360 isolates tested, 316 were identified as F. asiaticum, accounting for 87.78%; the remaining 44 isolates were identified as F. graminearum sensu stricto (s.s.), representing only 12.22% of the total. Among the F. asiaticum isolates, 63 were identified as carrying the trichothecene nivalenol genotype, 203 as carrying the 3-acetyldeoxynivalenol (3ADON) genotype, and 50 as carrying the 15ADON genotype. In contrast, all 44 F. graminearum s.s. isolates exclusively harbored the 15ADON genotype. In 2024, F. asiaticum with the 3ADON genotype was the dominant population causing FHB in wheat fields of Hubei Province. Comparison with previous survey data suggests that the 3ADON genotype of F. asiaticum has been present in Hubei Province for an extended period. However, significant temporal variations in the population frequency of the 3ADON genotype has been observed in Hubei Province over the past 25 years: specifically, the proportion of the 3ADON genotype population increased by more than 1.60-fold, rising from 46.43% in 1999 to 74.52% in 2009; subsequently, a 1.32-fold reduction was recorded between 2009 and 2024, with the proportion decreasing to 56.39%. These findings hold significant implications for plant disease management and food safety in Hubei Province.