THE USE OF SPECIES-SPECIFIC DNA PROBES FOR THE IDENTIFICATION OF MYCOSPHAERELLA FIJIENSIS AND M-MUSICOLA, THE CAUSAL AGENTS OF SIGATOKA DISEASE OF BANANA

The polymerase chain reaction (PCR)-based technique of random amplific ation of polymorphic DNA (RAPD) was used to differentiate DNA from spe cies of the genus Mycosphaerella. DNA from two pathogens which cause S igatoka leafspot diseases of banana, M. fijiensis and M. musicola, and two other Mycosphaerella species which are commonly found on banana, M. musae and M. minima, gave distinct RAPD banding patterns with all P CR primers tested. PCR, using primer RC07, amplified a 1250 bp RAPD fr agment from all isolates of M. fijiensis obtained from 11 geographical origins. This fragment was absent from the other species of Mycosphae rella. In Southern blots of genomic DNA, this band hybridized exclusiv ely to DNA from M. fijiensis, and the pattern of hybridization suggest ed that it was binding to repeated DNA. A RAPD band amplified with pri mer PM06 obtained from M. musicola was also found to be species-specif ic. Southern analysis suggested that the fragment hybridized to a sing le-copy sequence in the M. musicola genome. Total genomic DNA from M. musicola was found to be a species-specific hybridization probe. Dot-b lots confirmed the specificity of these probes, and could be used to i dentify isolates of Mycosphaerella which cause Sigatoka disease of ban ana in south-east Asia.