Genetic Variation Among Fusarium graminearum Isolates Causing Head Blight of Wheat Based on Vegetative Compatibility Grouping

Abstract

Genetic variation among Fusarium graminearum isolates causing head blight of wheat was investigated using vegetative compatibility grouping (VCG) to assess population structure, diversity, and potential implications for disease epidemiology. Field samples were collected from wheat-growing regions exhibiting typical head blight symptoms, including spike bleaching, premature grain shriveling, and reduced yield. Fungal isolates were obtained and purified, followed by vegetative compatibility testing through nitrate non-utilizing (nit) mutant complementation assays. Results revealed substantial genetic diversity among F. graminearum populations, with isolates clustering into multiple distinct vegetative compatibility groups. The presence of several VCGs within and across regions indicated a heterogeneous population structure, suggesting both local adaptation and long-distance dispersal of inoculum. Certain VCGs were more frequently associated with highly aggressive isolates, indicating a potential link between vegetative compatibility and pathogenic variability. Differences in growth rate and virulence were observed among groups, highlighting functional diversity within the species complex. The study demonstrates that VCG analysis is an effective tool for assessing intraspecific variation and provides valuable insights into the population biology of F. graminearum. These findings contribute to a better understanding of pathogen diversity and support the development of targeted disease management strategies, including resistant cultivar deployment and region-specific control measures for wheat head blight.