Pathogenic and Molecular Diversity of Fusarium oxysporum f. sp. lycopersici Races in Commercial Tomato Farms

Abstract

Fusarium oxysporum f. sp. lycopersici is the causal agent of Fusarium wilt, one of the most destructive diseases affecting tomato production worldwide. The occurrence of different pathogenic races and genetically diverse populations complicates disease management and reduces the durability of resistant cultivars. The present study investigated the pathogenic and molecular diversity of F. oxysporum f. sp. lycopersici races collected from commercial tomato farms. Diseased tomato plants exhibiting wilting, vascular browning, chlorosis, and stunted growth were sampled from major tomato-growing regions, and fungal isolates were obtained using standard isolation techniques. Pathogenicity assays were conducted on differential tomato cultivars carrying specific resistance genes to identify pathogenic races and evaluate variations in virulence among isolates. Significant differences in disease severity and aggressiveness were observed, indicating the presence of multiple pathogenic races within the studied populations. Molecular characterization was performed using polymerase chain reaction (PCR)-based markers and sequence analysis of conserved genomic regions to assess genetic diversity and phylogenetic relationships among isolates. The results revealed substantial molecular variability among pathogen populations, with certain isolates forming genetically distinct clusters associated with geographical origin and virulence characteristics. The coexistence of diverse races and genetically variable populations suggests continuous evolutionary adaptation driven by host selection pressure and agricultural practices. Correlation between pathogenic variability and molecular diversity highlighted the complex population structure of the pathogen in commercial tomato production systems. The findings provide valuable insights into the epidemiology and evolution of Fusarium wilt pathogens and support the development of effective resistance breeding programs and integrated disease management strategies aimed at sustaining tomato productivity.