INHERITANCE OF ADULT PLANT RESISTANCE TO POWDERY MILDEWIN SOME CROSSES OF BREAD WHEAT

Eight F2 populations of crosses carried out between the resistant cultivar Amigo and 8 susceptible bread wheat cultivars were evaluated to study the inheritance of resistance to powdery mildew (Pm) caused by Blumeria. graminis f.sp. tritici and also to estimate the number and action of genes related to adult plant resistance. The response to powdery mildew disease was studied in a conditioned glass house and natural infection in the open field. Individual plants were scored and classified as resistant or susceptible according to a specific scale. The tested local wheat cultivars showed susceptible responses at both seedling and adult stages, while the Amigo cultivar was susceptible at seedling stage and resistant at adult stage. The F2 plants of all tested crosses were susceptible at seedling stage and resistant at the adult stage. Obtained results revealed that the inheritance of resistance is ruled by a single gene in the crosses Amigo/Sids12 and Amigo/Misr2; and by two recessive genes in Amigo/Gemmeiza 11 cross. The inheritance of resistance in F2 populations of Amigo/Sakha 95, and Amigo/Giza 171 crosses is controlled by two dominant genes, while in Amigo/Gemmeiza 12, Amigo/Sakha 94 and Amigo/Misr1 crosses is conditioned by two incompatible dominant genes. Sakha 95 and Giza 171 wheat cultivars were the best and suitable for transferring the adult plant resistance gene Pm17.