Vegetative Compatibility Groups of Fusarium oxysporum f.sp. adzukicola and Nonpathogenic Fusarium oxysporum on Adzuki Bean Isolated from Adzuki Bean Fields in Hokkaido.

Abstract

Fusarium oxysporum f. sp. adzukicola and nonpathogenic F. oxysporum against adzuki bean were grouped using vegetative compatibility tests with nitrate non-utilizing (nit) mutants. One hundred and twelve pathogenic isolates collected from 20 areas in Hokkaido were classified into the largest vegetative compatibility group (VCG) including two subgroups, one small VCG, four self-vegetative incompatible isolates and three single self-compatible isolates.All three races of this fungus were grouped within the largest VCG. The 199 onpathogenic F. oxysporum isolates were incompatible with the VCGs of F. oxysporum f. sp.adzukicola mentioned above and the isolates examined except for 15 single self-compatible isolates were classified into 25 VCGs. Sixteen VCGs out of 25 VCGs of the nonpathogenic isolates contained isolates from soil samples of both non-infested and infested fields in Tokachi district. Moreover, 162 isolates (81.3% of all isolates tested) belonged to these 16 VCGs. No marked difference in the population structure of nonpathogenic F. oxysporum was observed between the infested and noninfested (Tokachi) district.