TEMPERATURE AND RESISTANCE GENE INTERACTIONS IN THE EXPRESSION OF RESISTANCE TO BLUMERIA-GRAMINIS F SP. TRITICI

The influence of temperature on the resistance to powdery mildew cause d by Blumeria graminis (DC.) E.O. Speer f. sp. tritici Em. Marchal, wa s evaluated on six wheat cultivars/lines, Axminster/8 Chancellor (Cc) (Pml), Chul/8Cc (Pm3b), Yuma/8*Cc (Pm4a), VPM1 (Pm4b), Kavkaz (Pm8), and Chancellor, at two temperatures of 25EC and 15EC with two isolate s of powdery mildew. Resistance, based on the components of latency pe riod, infection type, colony number per unit leaf area, per cent infec ted leaf area, and AUDPC, was much less effective at 15EC than at 25EC for VPM1 and Yuma/8Cc, but no resistance shift was observed for Kavk az and Axminster/8Cc, indicating the difference of temperature-sensit ivity among Pm gen es or among the interactions of individual host gen es with corresponding powdery mildew pathogen genes.