Molecular And Cytogenetics Identification Of Wheat-secale Africanum 5R Introgression Lines

Genus Secale(Secale L., 2n=2x=14, RR) belongs to Poaceae(syn. Gramineae), in the tribe Triticeae, and is a member of tertiary gene pool of bread wheat since it has largely different chromosomes compared with wheat. As it contains a variety of genes associated with resistance to many cereal diseases, sprouting, drought, winter hardiness and high protein content, genus Secale comes to be an important source of genes for morphological and biochemical development in wheat breeding. As far as now, the main study in wheat breeding focus on cultivated rye(S. cereale L.), while the wild Secale species have been relatively few studied. Wild Secale species, Secale africanum Stapf.(RafrRafr), is an important species in genus Secale which widely distributed in southern Africa and now verging on extinction as for the other species invasion. S. africanum now has no more than 10 population all around the world.The plant of S. africanum Stapf is short, and has excellent resistance to various diseases. Therefore, it serves as potential source of genes in wheat breeding. This study focused on the development of a variety of Secale chromosome specific molecular markers, molecular cytogenetic identification of a series of new wheat–S. africanum introgression lines, and investigation of the effects of disease resistance and agronomic performance of wheat-S. africanum introgression lines. The research results showed as follows:Total 19 pairs of PLUG(PCR-based Landmark Unique Gene) primers of group 5 were used for identifying the wheat-S. africanum introgression lines. One introgression line, N39-3-4-5 neither has S. africanum chromatin nor group D chromosomes of wheat. N39-3-27-n4 、 N39-3-28-1 、 N39-3-28-3 、 N39-3-3-1 、 N39-3-4-2 、 N39-3-4-4 had incomplete 5RafrS and lost 5RafrL, were supposed to be potential translocation lines. N36-5-4-n2 and N36-5-4-n3 had complete 5Rafr and lost group D chromosomes. It need more study to identify these introgression lines.The FISH showed that both N39-3-27-n3 and N39-3-27-n7 had 42 chromatins, including a pair of 5RafrS.5DL translocated chromosomes. These two introgression lines were found to be 5RafrS.5DL translocation lines. Besides, the FISH signal indicated the different modes of recombination between the two 5RafrS.5DL translocation lines. Specifically, the 5RafrS of N39-3-27-n3 showed the FISH signals of 5RafrL, suggesting that there must be mutation in the 5Rafr before the recombination between 5RafrS and 5DL.The wheat-rye introgression lines in our study showed strong resistance to stripe rust. But the introgression of S. africanum chromosome 5Rafr leads to wrinkle of the seed of addition lines. On the other hand, the thousand seed weight of 5Rafr addition lines is higher than that of Chinese Spring.