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 Erysiphe graminis tritici to identify new genes/alleles for resistance. The wheats were tested with 13 isolates that had been characterized from responses on differential lines with known resistance genes. Gene Mlk which 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 wheat, 'W150', is conferred by a single gene also allelic to Pm3 and now designated Pm3e. The near-isogenic line 'Michigan Amber/8*Cc' possesses another allele now designated Pm3f. A Syrian land variety of common wheat shows mildew resistance that is conditioned by the combination of genes Pm1 and Pm3a. Finally, two accessions of Triticum aestivum ssp. sphaerococcum appeared to possess the Pm3c allele.