AN ASSESSMENT OF AESCULIN HYDROLYSIS, VEGETATIVE COMPATIBILITY AND DNA POLYMORPHISM AS CRITERIA FOR CHARACTERIZING PATHOGENIC RACES WITHIN FUSARIUM-OXYSPORUM F-SP VASINFECTUM

Fifteen strains, assigned to four pathogenic races of Fusarium oxysporum f.sp. vasinfectum on the basis of host range, were characterized by means of vegetative compatibility, restriction fragment length polymorphisms (RFLPs) and pigmentation on aesculin-containing medium. Isolates were divided into two major vegetative compatibility groups (VCGs) comprising Races 1 and 2 (V1) and Race 3 (V2). The two VCGs were represented by a single RFLP pattern. An additional RFLP pattern was observed for a single Race 4 isolate. Isolates received as belonging to Races 2, 3 and 4 blackened aesculin agar, while designated and presumed Race 1 isolates gave a negative reaction.