GENETIC-STRUCTURE OF SOIL POPULATION OF F UNGUS FUSARIUM-OXYSPORUM SCHLECHTEND, FR - MOLECULAR REIDENTIFICATION OF THE SPECIES AND GENETIC DIFFERENTIATION OF ISOLATES USING POLYMERASE CHAIN-REACTION TECHNIQUE WITH UNIVERSAL PRIMERS (UP-PCR)

The genetic structure of three soil populations of fungus Fusarium oxy sporum was analyzed using polymerase chain reaction with universal pri mers (UP-PCR). Distinct UP-PCR variants revealed by means of cross-dot hybridization of amplified DNA and restriction analysis of nuclear ri bosomal DNA represent subspecies or sibling species of F. oxysporum; T he remaining isolates of F. oxysporum showed moderate UP-PCR polymorph ism characterized by numerous types, whose relatedness was analyzed by computer treatment of the UP-PCR patterns. The genetic distance trees based on the UP-PCR patterns, which were obtained with different univ ersal primers, demonstrated similar topology. This suggests that evolu tionarily important genome rearrangements correlatively occur within t he entire genome. Isolates representing different UP-PCR polymorphisms were encountered in all populations, being distributed asymmetrically in two of these. In general, soil populations of F. oxysporum were re presented by numerous genetically isolated groups with a similar genom e structure. The genetic heterogeneity of the isolates within these gr oups is likely to be caused by the parasexual process. The usefulness of the UP-PCR technique for population studies of F. oxysporum was dem onstrated.