RADIATION-INDUCED NONHOMOLOGOUS WHEAT AGROPYRON-INTERMEDIUM CHROMOSOMAL TRANSLOCATIONS CONFERRING RESISTANCE TO LEAF RUST

The Agropyron intermedium chromosome 7Ai # 2 is the source of the leaf rust resistance gene Lr38 which was transferred to wheat by irradiati on. The chromosomal constitutions of eight radiation-induced rust-resi stant wheat-Agropyron intermedium derivatives were analyzed by C-bandi ng and genomic in-situ hybridization (GISH). Five lines were identifie d as wheat-Ag. intermedium chromosome translocation lines with the tra nslocation chromosomes T2AS.2AL-7Ai # 2L, T5AL.5AS-7Ai # 2L, T1DS.IDL- 7Ai # 2L, T3DL .3DS-7Ai # 2L, and T6DS.6DL-7Ai # 2L. The sizes of the 7Ai # 2L segments in mitotic metaphases of these translocations are 2. 42 mum, 4.20 mum, 2.55 mum, 2.78 mum, and 4.19 mum, respectively. One line was identified as a wheat-Ag. intermedium chromosome addition lin e. The added Ag. intermedium chromosome in this line is different from 7Ai # 2. This line has resistance to leaf rust and stem rust. Based o n the rust reactions, and the C-banding and GISH results, the remainin g two lines do not contain any Ag. intermedium-derived chromatin.