IDENTIFICATION OF POWDERY MILDEW RESISTANCE GENES IN SOFT RED WINTER-WHEAT CULTIVARS AND OHIO BREEDING LINES

Eight-day-old seedlings of seven soft red winter wheat cultivars and f our elite breeding lines were tested for the presence of powdery milde w resistance genes with 14 isolates of Blumeria graminis f. sp. tritic i. These isolates were characterized for their virulence on differenti al wheat cultivars and lines with single genes for powdery mildew resi stance. Phenotypic reactions of the cultivars and lines to each isolat e were assessed 8 days after inoculation. Differential reactions and p edigree information were used to determine the presence of putative po wdery mildew resistance genes. The B. g. tritici isolates detected pow dery mildew resistance gene Pm3a in AGRA brand GR915, and pedigree inf ormation indicated that Freedom contained Pm8. No Pm genes were detect ed in Cardinal, Clark, Dynasty, or Titan. The gene Pm3a was present in breeding lines OH470 and OH493-1, and gene Pm17 was detected in OH464 . OH490 contained gene Pm2 or Pm6, or possibly both; the isolates coul d not differentiate these two genes.