Assessment of genetic diversity and population structure of<em> Fusarium</em> species from the <em>Fusarium fujikuroi</em> species complex causing Fusarium stalk rot of maize

Fusarium stalk rot (FSR) caused by the Fusarium species complex is an economic threat to maize cultivation all over the world. We investigated the population structure and genetic diversity of Fusarium spp. obtained from five major maize-growing regions of India. The Tef-1α locus was used for phylogenetic analysis of geographically distinct isolates of Fusarium verticillioides, F. andiyazi, F. proliferatum, F. nygamai, and F. acutatum causing FSR. Geographical separation among four local populations contributed to 7.87% variance, whereas 92.12% of the variance was within popula-tions, suggesting a predominant influence of local adaptation or stochastic events like genetic drift within populations, with geographical separation playing a lesser but significant role in shaping genetic diversity. Genetic differentiation statistics between Fusarium species showed lower gene flow from haplotypes except in the population of F. acutatum and F. andiyazi having high GST values. In contrast, a high Kxy was reported, indicating elevated genetic differentiation between populations. The haplotype network analysis revealed the presence of eight distinct haplotypes which reflected pathogenic evolution and adaptive potential of Fusarium spp. The results offer a comprehensive framework for discussing the implications of genetic diversity in pathogen management and the evolutionary dynamics of the Fusarium spp. causing FSR of maize in the Indian subcontinent.