Pathogenicity Variation and Molecular Diversity of Fusarium oxysporum f. sp. ciceris Races Causing Wilt on Chickpea

Abstract

Pathogenic variability and molecular diversity among Fusarium oxysporum f. sp. ciceris (Foc) isolates associated with chickpea wilt were assessed to elucidate race structure and virulence differentiation across agroecological regions. Isolates collected from infected chickpea fields were evaluated for pathogenicity on differential host genotypes under controlled conditions, revealing significant variation in symptom expression, incubation period, and disease severity. Highly virulent isolates induced rapid vascular discoloration and plant mortality, whereas moderate and weakly pathogenic isolates showed delayed symptom development and restricted colonization. Molecular characterization using PCR-based markers and sequence analysis of ITS and housekeeping gene regions indicated substantial genetic polymorphism among isolates, clustering them into distinct phylogenetic groups corresponding partially with pathogenic races. Analysis of molecular variance demonstrated moderate genetic differentiation, suggesting both clonal propagation and limited gene flow within populations. Association between pathogenicity profiles and molecular clusters indicated partial linkage between virulence and genetic background. Environmental and host-driven selection pressures appeared to contribute to diversification of Foc populations in chickpea-growing regions. The observed variability highlights the dynamic nature of pathogen evolution and its implications for resistance breeding programs. Integration of molecular diagnostics with pathogenicity assays provides a robust framework for accurate race identification and disease management. These findings support the deployment of multi-line resistant chickpea cultivars and region-specific management strategies to mitigate yield losses caused by Fusarium wilt. Continuous monitoring of Foc population structure is essential for sustainable disease control under changing agricultural practices and climatic conditions.