Problems and Prospects of Alien Chromosome Integration in Wheat Cultivars

Remote hybridization was one of the essential methods for developing a broad series of wheat lines with alien translocation. Since the middle of last century, these lines were used in breeding process in Russia and some commercial wheat cultivars containing alien introgressions were developed. Wheat hybrids and varieties carrying translocations from related species or genera are an important source of rust resistance genes. Here we characterized Russian wheat cultivars and hybrid lines (Triticum aestivum/T. timopheevii, T. aestivum/Ae. speltoides) and their use in marker-assisted breeding.

It was shown that 5 of 25 varieties analyzed contain 1RS.1BL translocation. Some of varieties carry other types of introgressions that have not been identified before, namely 2DS.2SL, 5BS.5BL-5GL, and 6BS.6BL-6GL translocations, 6D/6Agi substitution from Agropyron intermedium and introgression of Aegilops tauschiigenetic material into 1D and 6D chromosomes. The chromosome 6D/6Agi of cultivar Tulaikovskaya possesses genes conferring resistance to leaf, stem, and yellow rusts and powdery mildew, which are not allelic to any known rust resistance genes. On the basis of EST analysis we selected markers specific for 6Agi chromosome for their subsequent use in molecular-assisted breeding.

Four lines with durable resistance to leaf rust were selected from 74 hybrid lines. Marker-assisted backcrossing was used for developing lines carrying a single Ae. speltoides and T. timopheevii translocations. It was shown that lines carrying translocations from Ae. speltoides (21-4 with T5BS.5BL-5SL, 17-7 with T6BS.6BL-6SL) are resistant to leaf rust. Line 11-8 with 7D/7S substitution is completely resistant to leaf rust and powdery mildew. Lines 5366-180 and 3862-5 with T. timopheevii translocations were resistant to leaf rust and stem rust, respectively. According to molecular analysis line 3862-5 may possess the Sr36 gene. The LrTt2 gene of 5366-180 may be allelic to Lr18. The rust resistance genes identified in other selected lines (21-4, 17-7, 11-8) haven’t been described earlier.

The variety Tulaikovskaya and lines 21-4, 17-7, 11-8, 3862-5 5366-180 were used as donors of resistance genes in molecular-assisted breeding of spring and winter wheat cultivars. As a result the spring wheat breeding lines with high productivity and resistance to fungal diseases have been developed. The development of winter wheat lines is in progress.

It was demonstrated that alien translocations as well as the alien substitutions of whole chromosome may successful exist in genome of commercial wheat cultivar.