Relationship between Partial Resistance and Inheritance of Adult Plant Resistance Gene LR 46 of Leaf Rust in Six Bread Wheat Varieties

Leaf rust caused by Puccinia triticina Eriks. is an important disease of wheat (Triticum aestivum L. ) in Egypt and worldwide. Six Egyptian bread wheat varieties were evaluated and tested for their levels of adult plant resistance to leaf rust at Sadat City location during three successive growing seasons i. e.2011/12, 2012/13 and 2013/14. Wheat varieties Gemmeiza 9, Giza 168 and Gemmeiza 7 showed the highest levels of partial resistance and lower values of percentage final rust severity (FRS) did not exceeded up to 30 % as well as area under disease progress curve (AUDPC) not more than 250. On the other hand, Gemmeiza 1, Sakha 93 and Sids 1 were highly susceptible or fast rusting varieties. These varieties showed the highest levels of percentage FRS and AUDPC compared with the partially resistant varieties under the same field conditions. To determine the inheritance of adult plant resistance to leaf rust, tested wheat varieties were crossed with seven adult plant leaf rust resistance monogenic lines i. e. Lr 38, Lr 42, Lr 43, Lr 44, Lr 45, Lr 46 and Lr 47. The resulted F1 plants were selfed to produce F2 seeds. F2 plants were tested at adult plant stage under field conditions at Sadat City location during 2012/13 growing season. Segregations of F2 plants at adult plant stage revealed that the wheat varieties Giza 168 and Gemmeiza 9 have the same three genes i. e. Lr 45, Lr 46 and Lr 47. While the other tested varieties Sakha 93, Gemmeiza 1, Gemmeiza 7 and Sids 1 do not carry any of the tested leaf rust resistance genes.