GENETIC-VARIATION IN POWDERY MILDEW OF BARLEY - DEVELOPMENT OF RAPD, SCAR, AND VNTR MARKERS

Isolates of Erysiphe graminis f. sp. hordei derived from airborne conidia and progeny of specific crosses were screened for random amplified polymorphic DNA (RAPD) variation detected with 10-base primers. Using two DNA samples, 58 of 76 primers yielded good amplification products. Twenty-seven primers were screened further on a test set of 16 E.g. hordei isolates collected from throughout Europe. Approximately 119 resolvable bands were reproducibly amplified, 56 bands were variable, and each primer yielded at least one polymorphism. A subset of 10 of these primers detected 30 polymorphisms in the European test set but only 19 variable bands in 48 isolates collected with a stationary spore trap. In addition to the RAPD markers, we developed six sets of specific primers that detected variation, five of which detected multiple alleles, one detected the presence and absence of a band, and a seventh was monomorphic. These polymerase chain reaction markers, in conjunction with virulence and fungicide sensitivity, are being used to investigate evolutionary processes and genetic linkage in the barley powdery mildew pathogen.