Abstract :
This investigation was carried out to identify stem rust resistance genes in the six Egyptian bread wheat cultivars Sakha 93, Sids 1, Gemmeiza 10, Gemmeiza 11, Misr 1 and Misr 2. F1 seed were developed from the crosses between the six wheat cultivars and each of the wheat monogenic lines of Sr 11, Sr 32, Sr 33 and Sr 40 in 2012/2013 season. In the next season, 2013/2014, F2 plants were tested under field conditions after artificial inoculation with a mixture of stem rust physiological races at Sids Agricultural Research Station, ARC, Egypt. Chi-square test was used to test the fitness of segregation in F2 plants for each cross to the expected ratios. Out of the six wheat cultivars, the two cultivars Sids 1 and Gemmeiza 10 showed no or negligible segregations in F2 crosses between them and each of the four stem rust monogenic lines. All or majority of F2 plants showed resistant type of reaction to stem rust under field conditions indicating that both cultivars expected to carry Sr 11, Sr 32, Sr 33 and Sr 40 adult-plant stem rust resistance genes. On the other hand, the remaining four wheat cultivars, Sakha 93, Gemmeiza 11, Misr 1 and Misr 2 showed significant segregation in their F2 crosses with the monogenic lines. Segregations among F2 plants were toward resistance in the crosses with the two cultivars Sakha 93 and Gemmeiza 11 while it was toward susceptibility in the crosses with the two cultivars Misr 1 and Misr 2. Resistance found to be dominant over susceptibility in the crosses between the two cultivars Sakha 93 and Gemmeiza 11 and the monogenic lines except for the cross Sakha 93 x Sr 32. Meanwhile, susceptibility was dominant over resistance in the crosses between the two cultivars Misr 1 and Misr 2 and the monogenic lines. The results of this study indicate the importance of the two Egyptian bread wheat cultivars Sids 1 and Gemmeiza 10 as a source of adult-plant stem rust resistance genes which could be utilized in wheat breeding program for improving stem rust resistance in Egypt.
