CHROMOSOME LOCATION OF GENES FOR RESISTANCE TO POWDERY MILDEW IN COMMON WHEAT (TRITICUM-AESTIVUM L) .1. MILK AND OTHER ALLELES AT THE PM3 LOCUS

Several wheat cultivars/lines were inoculated with isolates of Erysiph e graminis tritici to identify new genes/alleles for resistance. The w heats were tested with 13 isolates that had been characterized from re sponses on differential lines with known resistance genes. Gene Mlk wh ich occurs in cultivars 'Kolibri'. 'Syros', 'Ralle' and several other European common wheats was found to be an allele at the Pm3 locus and is now designated Pm3d. The mildew resistance in an old Australian whe at, 'W150', is conferred by a single gene also allelic to Pm3 and now designated Pm3e. The near-isogenic line 'Michigan Amber/8Cc' possesse s another allele now designated Pm3f. A Syrian land variety of common wheat shows mildew resistance that is conditioned by the combination o f genes Pm1 and Pm3a. Finally, two accessions of Triticum aestivum ssp . sphaerococcum appeared to possess the Pm3c allele.