Efficiency of Yellow Rust Resistance Genes Yr5, Yr10, Yr15 and Yrsp in Improving the Two Egyptian Bread Wheat Cultivars Sids 12 and Gemmeiza 11

A filed and greenhouse study was conducted at Sakha Station during 2015-2020 wheat seasons to enhance stripe rust resistance of the two Egyptian wheat cultivars Sids12 and Gemmeiza11 using the four monogenic lines Yr5, 10, 15 and Sp. The two wheat cultivars were crossed to the four monogenic lines to obtain eight F1 hybrids then selfed to produce F2 populations and selected F3 families. In the field, parents, F1, F2, F3, were inoculated with a mixture of the dominating stripe rust pathotypes (Pst). Evaluation of the monogenic lines indicated that wheat genotypes carrying stripe rust resistance genes Yr5 and Yr15, at both seedling and adult plant stages exhibited high resistance to Pst pathotypes. More than 75% of lines in both mapping populations showed susceptibility reaction indicating that both cultivars having similar genetic constitution against the tested stripe rust races. F1 field response confirmed that the four tested Yr genes are effective against the tested stripe rust races and resistant reaction is dominating over susceptibility. Segregation ratios of the eight F2 crosses indicated that the cultivars differ in three, two, or one genes with the monogenic lines. Average coefficient of infection recorded the lowest mean values for F2 crosses with Yr5 and Yr15 in both cultivars indicating that the two genes shifted the F2 population means toward resistance more than Yr10 and YrSp. Efficiency of the four genes can be arranged in the following order Yr5 ˃Yr15 ˃YrSp ˃Yr10 with Sids12 background and Yr5 ˃Yr15 ˃Yr10 ˃YrSp with Gemmeiza11 background.