A single recessive gene confers effective resistance to powdery mildew of field pea grown in northern New South Wales

Reactions to powdery mildew (Erysiphe pisi Syd.) of a range of varieties, advanced lines and pea germplasm from the Australian Temperate Field Crops Collection (ATFCC) were evaluated under field conditions at Narrabri, New South Wales. Thirteen resistant genotypes, including 3 M257 sister lines [M257-2-1 (Mukta), M257-3-6 and M257-5-1], Glenroy, Kiley and PSI 11 from Australian breeding programs, and LE 25 (ATC 1275), ATC 649, ATC 767, ATC 823, ATC 1036, ATC 1121 and ATC 1181 from the ATFCC, along with 8 susceptible lines Dinkum, Bohatyr, Jupiter, Greenfeast, Solara, P441-6, Trapper and Cressy Blue, were used to make resistant × resistant, resistant × susceptible and susceptible × susceptible combinations to examine the inheritance of resistance. Parental lines and F1 and F2 populations were evaluated in the field under natural disease epiphytotics at the Plant Breeding Institute, Narrabri, during the winters of 1996 and 1997. In 1996, resistant and susceptible F2 plants were selected from 5 crosses, and further examined as F3 families in 1997. No fully resistant line was identified among the parents. F1 reactions indicated that resistance was governed by recessive genes and there were no maternal effects. Segregation patterns in the F2 and F3 generations supported the hypothesis of resistance in the genotypes M257-5-1, Glenroy, Kiley, ATC 649 and ATC 1121 being conferred by the same single recessive gene.