REPETITIVE GENOMIC SEQUENCES FOR DETERMINING RELATEDNESS AMONG STRAINS OF FUSARIUM-OXYSPORUM

Polymorphic restriction fragments containing moderately repetitive DNA sequences have been identified in the fungus Fusarium oxysporum. Arbitrarily chosen genomic clones pEY1, pEY2, pEY7, and pEY10, containing 1.1, 1.1, 2.3, and 1.2 kb of fungal DNA, respectively, were used to identify the repetitive sequences. When used as probes in DNA/ DNA hybridization analyses of restriction endonuclease-digested DNAs from various strains of F. oxysporum, these probes identified distinctive banding patterns for each strain. These probes were used to infer the phylogenetic relationships among crucifer-infecting strains of F. oxysporum. Parsimony analysis suggests a common ancestry for strains representing different races of F. o.f. sp. conglutinans, but a distinct ancestry between these and strains of F. o. raphani and F. o. matthioli. A geographical subpopulation of F. o. conglutinans was identified by pEY2. Clone pEY10 was useful to fingerprint individual strains F. o. cubense, causal agent of Fusarium wilt of banana.