Genetic diversity among isolates of Fusarium oxysporum f.sp. canariensis

Fusarium oxysporum f. sp. canariensis causes vascular wilt disease of Phoenix canariensis, the Canary Island date palm. Seventy-two isolates of this fungus were obtained from diverse geographic locations including France, Japan, Italy, the Canary Islands, and California, Florida and Nevada, USA. The isolates were tested for vegetative compatibility and for similarities based on mitochondrial DNA (mtDNA), single-copy sequences and repetitive DNA (pEY10) polymorphisms. Seventy-one percent of the isolates belonged to a single vegetative compatibility group (VCG 0240), and four closely related mitochondrial RFLP patterns were found. A subset of the isolates was further tested for single-copy RFLPs and repetitive DNA fingerprints. Only four single-copy RFLP haplotypes were found among 25 representative isolates of E oxysporum f. sp. canariensis tested, using nine polymorphic single-locus probe/enzyme combinations. Finally, 32 different pEY10 DNA fingerprints were found out of 57 isolates examined. Overall the results indicate that E oxysporum f. sp. canariensis is a single lineage with a low to moderate level of genetic diversity.