USE OF RANDOM AMPLIFIED POLYMORPHIC DNA MARKERS FOR THE DETECTION OF GENETIC-VARIATION IN MAGNAPORTHE POAE

Random amplified polymorphic DNA (RAPD) markers were used to survey genetic variability among 35 Magnaporthe poae isolates. Amplification patterns for 23 of the 35 isolates were phenotypically unique and readily distinguishable from an outgroup of six additional ectotrophic, dematiaceous fungi. These results indicate the utility of RAPDs as an accurate and reproducible means of identifying individuals within the species. Analysis of molecular variance demonstrated that isolates of M. poae were significantly different (P = 0.001) among 12 sampling locations. This finding may have important implications for research programs concerned with obtaining genetically representative isolates of M. poae. Moreover, genetic variation was found among isolates within all but one location and within both mating types, suggesting that genetic variation is present among naturally occurring populations, even though natural sporulation has never been observed in M. poae. From a subset of 12 isolates, pathogenicity was found to decrease as genetic distance from the most pathogenic isolate increased. The use of RAPD markers to obtain measurements of genetic relatedness and genetic variation within and between fungal populations should aid in our understanding of the disease pathology and reproductive biology of this species.