Vegetative Compatibility Groups in Fusarium oxysporum f.sp. ciceris and F. oxysporum Non‐pathogenic to Chickpea

Abstract

AbstractForty‐seven isolates of Fusarium oxysporum f.sp.ciceris, representative of the different pathogenic races and originating from California, India, Tunisia and Spain, and twenty‐five non‐pathogenic F. oxysporum isolates obtained from chickpea roots in Algeria, Italy, Morocco, Pakistan and Spain, were analyzed for vegetative compatibility. Only one vegetative compatibility group (VCG) was found among the 47 isolates of F. oxysporum f.sp. ciceris, although some isolates failed to complement with one or more isolates in this VCG. Among the twenty five non‐pathogenic isolates, we found three multi‐member VCG, each group containing two to five isolates. Pathogenic and non‐pathogenic isolates complemented sporadically. Most of the non‐pathogenic isolates were compatible with a yellowing‐type low virulent F. oxysporum f.sp. ciceris isolate (Foc USA 3/1 JG), thus suggesting the possibility of the existence of transition isolates between pathogenic and non‐pathogenic populations. Heterokaryon formation between compatible isolates was shown by both pathogenicity and molecular tests. The virulence pattern displayed by the heterokaryons indicated the presence of genetic factors controlling pathogenicity from both parental races. RAPD‐PCR analysis of total DNA of the heterokaryon also showed the presence of the two genomes in it. The existence of a single VCG in the F. oxysporum f.sp. ciceris population support the hypothesis of its monophyletic origin.