GENETIC-CHARACTERIZATION BY RAPD ANALYSIS OF ISOLATES OF FUSARIUM-OXYSPORUM F SP. ERYTHROXYLI ASSOCIATED WITH AN EMERGING EPIDEMIC IN PERU

An epidemic of vascular wilt caused by Fusarium oxysporum f. sp. eryth roxyli is currently occurring on Erythroxylum coca var. coca in the co ca-growing regions of the Huallaga Valley in Peru. Random amplified po lymorphic DNA (RAPD) analysis of isolates of the pathogen was undertak en to elucidate its genetic complexity, as well as to identify a speci fic DNA fingerprint for the pathogen. Two hundred isolates of Fusarium were collected from 10 coca-growing regions in Peru. Of these, 187 we re confirmed to be F. oxysporum, and 143 of the F. oxysporum were show n to be pathogens of coca by a root-dip pathogenicity test. The pathog ens could be grouped into two subpopulations based on RAPD analysis, a nd no polymorphism in RAPD pattern was observed among isolates of eith er subpopulation. Both subpopulations were present in the central Hual laga Valley, where earliest reports of the epidemic occurred, RAPD ana lysis could easily distinguish the isolates of F. oxysporum f. sp. ery throxyli from the nonpathogenic isolates of F. oxysporum from E, coca var. coca, indicating its utility in DNA fingerprinting.