GENETIC-VARIATION AMONG A WORLD-WIDE COLLECTION OF ISOLATES OF FUSARIUM-OXYSPORUM F SP CUBENSE ANALYZED BY RAPD-PCR FINGERPRINTING

To breed or select banana cultivars with durable resistance to Fusarium wilt it is necessary to determine the genetic variation that exists within the pathogen, Fusarium oxysporum f. sp. cubense, as potentially resistant cultivars ideally should have resistance to all variants of the pathogen. We have analysed genetic variation within a world-wide collection of isolates of F. oxysporum f. sp. cubense which represented races 1, 2 and 4 and 11 different vegetative compatibility groups (VCGs) using RAPD-PCR. Comparison of the RAPD-PCR banding patterns both visually and by phenetic analysis sub-divided isolates of F. oxysporum f. sp, cubense into two major groups. Group 1 contained isolates belonging in VCGs 0120, 0121, 0122, 0126, 01210, 01211 and 01212 and group 2 contained isolates belonging in VCGs 0123, 0124, 0124/5 and 0125. The RAPD-PCR banding patterns were generally VCG specific and it was possible to determine the genetic relatedness between the different VCGs and of isolates within each VCG. The two groups differentiated by RAPD-PCR analysis correspond with previous classifications based on volatile production and electrophoretic karyotyping. In contrast, there was no correlation between RAPD-PCR banding pattern and race. The results support the hypothesis that F. oxysporum f. sp. cubense co-evolved with edible bananas and their wild diploid progenitors in South East Asia.