Inheritance of Resistance to Leaf Rust in 13 Wheat Near-Isogenic Lines

Abstract

The inheritance of seedling and adult plant resistance against race no 49 of P. triticina and more virulent race mixture, was studied under greenhouse and field conditions sequentially. The monogenic line Lr34 was crossed with each of Lr,s : B, 11, 12, 13, 17, 24, 31 and 35.The line Lr10 was crossed with either of Lr9, 23 and 24. Finally the line Lr35 was crossed with each of Lr31 and 38. At seedling stage, the cross Lr34 + Lr24 was segregated in F2 as ratio 9(R): 7(S), while at adult stage no segregation was observed and the resistance was dominant. Lr35 + Lr38 at seedling and adult stage F2 segregated to 9 (R): 7(S). On the other hand Lr9 + Lr10 at seedling stage F2 segregated to 7(R): 9(S), but at adult stage appeared no segregated and dominance of resistance. Likewise Lr10 + Lr23 at seedling stage F2 segregated to 1(R): 15(S), while adult stage segregated to 13(R): 3(S). The cross Lr34 + Lr35 at seedling stage F2 showed no segregation, the dominance was in the side of susceptibility, while adult stage segregated to 13(R) : 3(S). The rest crosses of adult stage appeared segregated and dominance tend to the side of susceptibility, but at seedling stage all crosses showed no segregation and dominance tend to the side of susceptibility. This investigation confirmed on studying the genetics of resistance at adult stage that have expression rather than seedling stage.