CHROMOSOMAL LOCATION OF GENES FOR RESISTANCE TO POWDERY MILDEW IN COMMON WHEAT (TRITICUM-AESTIVUM L. EM. THELL.) .4. GENE PM24 IN CHINESE LANDRACE CHIYACAO

Chinese wheat landrace Chiyacao exhibited a response pattern different from that of the cultivars/lines possessing documented Pm genes after inoculation with 106 isolates of Erysiphe graminis f. sp. tritici. To characterize this resistance and to determine the chromosomal locatio n of the gene or genes present, we crossed the landrace to susceptible cultivar 'Chinese Spring' and also to a set of 21 'Chinese Spring' mo nosomic lines. Monosomic F-1 plants were allowed to self-pollinate and to produce F-2 seeds. Seedlings of F-2 plants and their parents were inoculated with isolates nos. 5 and 12 of Erysiphe graminis f. sp. tri tici. The results revealed that one major dominant gene is located on chromosome 6D of Chinese common wheat landrace Chiyacao. The new gene is designated Pm 24.