Vegetative Compatibility Groups within Populations of Fusarium oxysporum f. sp. cubense Causing Banana Fusarium Wilt in Myanmar

Abstract

Vegetative compatibility groups (VCGs) are used to study genetic relationships among asexually reproducing plant pathogenic fungi. VCGs are strongly associated with specific Fusarium oxysporum f. sp. cubense (Foc) races and often correlate with pathogenicity. In this study, 20 Foc isolates, the causal agent of banana Fusarium wilt, were analyzed using VCG analysis to identify strains and assess their diversity. The experiment was conducted from August 2024 to February 2025 at the Laboratory of the Department of Plant Pathology, Yezin Agricultural University, Myanmar. The 20 isolates tested were previously confirmed as virulent and identified as Foc race 1 through pathogenicity and PCR assays carried out in the same Laboratory. Nit-mutants of each isolate were firstly induced on KPS media (potato dextrose agar medium amended with 1.5% potassium chlorate, KClO3) and generated on minimal media (MM). VCGs assay was performed on MM media by pairing the generated nit-mutants of each Foc isolate with nit-M mutants of 15 known Foc VCGs testers which were obtained from China. The ability of heterokaryon formation among isolates and VCGs testers was evaluated, and the corresponding physiological races were designated. Among the 20 isolates, 11 belonged to VCG 0124, eight to the VCG 0124/0125 complex, and one to VCG 0125, accounting for 55%, 40%, and 5% of the isolates, respectively. VCG analysis indicated that VCG 0124 was the most prevalent group, followed by the 0124/0125 complex and VCG 0125.The identification of these VCGs is consistent with earlier virulence and molecular studies, confirming that the isolates are pathogenic and belong to Fusarium oxysporum f. sp. cubense race 1. This study represents the first comprehensive investigation of Foc populations in Myanmar using VCG analysis.