OLIGONUCLEOTIDE FINGERPRINTING DETECTS GENETIC-VARIABILITY AT DIFFERENT LEVELS IN NIGERIAN MYCOSPHAERELLA FIJIENSIS

DNA fingerprinting with synthetic simple repetitive oligonucleotides s uch as (CA)(8) or (CAA)(5) detected polymorphisms between various isol ates of the ascomycete Mycosphaerella fijiensis, the causal agent of t he black Sigatoka disease of Musa. These microsatellite motifs are pre sent at multiple chromosomal locations and in high copy numbers in the Mycosphaerella genome, generating informative fingerprints with low b ackground. Variability exists on a macro- as well as a microgeographic al scale: it occurred within one lesion, between lesions of one plant, between plants, cultivars, and geographic locations. Mathematical ana lysis of the data produced dendrograms that demonstrated the presence of different genetically related groups of Mycosphaerella fijiensis in Nigeria.