Genetic diversity among isolates of Fusarium oxysporum f.sp canariensis

Fusarium oxysporum f.sp. canariensis causes vascular wilt disease of Phoeni x canariensis, the Canary Island date palm. Seventy-two isolates of this fu ngus were obtained from diverse geographic locations including France, Japa n, Italy, the Canary Islands, and California, Florida and Nevada, USA. The isolates were tested for vegetative compatibility and for similarities base d on mitochondrial DNA (mtDNA), single-copy sequences and repetitive DNA (p EY10) polymorphisms. Seventy-one percent of the isolates belonged to a sing le vegetative compatibility group (VCG 0240), and four closely related mito chondrial RFLP patterns were found. A subset of the isolates was further te sted for single-copy RFLPs and repetitive DNA fingerprints. Only four singl e-copy RFLP haplotypes were found among 25 representative isolates of F. ox ysporum f.sp. canariensis tested, using nine polymorphic single-locus probe /enzyme combinations. Finally, 32 different pEY10 DNA fingerprints were fou nd out of 57 isolates examined. Overall the results indicate that F. oxyspo rum f.sp. canariensis is a single lineage with a low to moderate level of g enetic diversity.