Inheritance of powdery mildew resistance in pea

Pea, an important grain legume crop, suffers significant yield and quality losses because of infections by the parasitic fungus Erysiphe pisi Syd., the causal agent of powdery mildew. Most pea cultivars in western Canada are susceptible to this fungus. The genetic basis of resistance found in certain Canadian cultivars is unclear. Resistant cultivars and lines were intercrossed with each other and crossed with susceptible lines to determine the genetic basis of resistance. Resistance in the cultivars Highlight, AC Tamor, Tara, Mexique 4, Stratagem and lines JI 210, JI 1951, JI 1210 was found to be conferred by a single recessive gene, er-1. The resistance in line JI 2480 is conferred by a different recessive gene, er-2. Resistance provided by er-1 was durable under both field and growth cabinet conditions, however, resistance of er-2 was broken under controlled growth conditions. Combining er-1 and er-2 in a cultivar could increase the durability of resistance. Key words: pea, Pisum sativum, powdery mildew, Erysiphe pisi, inheritance, resistance