Variability of agronomically important traits in spring wheat hybrids obtained by marker-assisted selection from crosses of winter wheat with spring wheat donors of resistance genes

Spring wheat is the main cereal crop in the West Siberian region of Russia and occupies more than 40 % of the acreage. The widening of the genetic diversity of this culture and the creation of new varieties with high productivity and resistance to environmental factors have always been a key problem of breeding. Winter wheat varieties which are characterized by a wide diversity of useful characters such as tolerance to abiotic stressors, productive tillers and yield can be used as a promising source of agronomically important traits. Despite the fact that the methodological approach to the introgression of the gene pool of winter wheat into the genome of spring wheat has been in use for a long time to increase the yield of spring varieties, at the moment there is little available information concerning the manifestation of valuable traits in offspring obtained from the winter and spring wheat hybridization. However, such results are important for assessing the combining ability of winter and spring wheat varieties and for the selection of potential parents by a complex of characters. For the identification of the winter and spring genotypes in the offspring resulting from the hybridization of winter and spring parents with the help of convenient breeding methods, a large sample size populations and a long period of cultivation of plant material are required. The application of MAS technologies and markers linked to the target loci can significantly decrease the time of development of new breeding lines. In creation of breeding lines resistant to leaf rust, the winter wheat varieties Filatovka and Biyskaya ozymaya, adapted for cultivation in the West Siberian region, were involved in a scheme of hybridization. Spring wheat introgression line 5366-180 ( Triticum aestivum / T. timopheevii ) и spring wheat cultivar Tulaikovskaya 10, containing genetic material of Thinopyrum intermedium were the donors of effective leaf rust resistance genes LrTt2 and Lr6Ai#2. The aim of this work was to evaluate the diversity of spring wheat forms obtained from these crosses on economically important traits and analysis of the genotype influence on their manifestation. The plants differing in winter and spring habits were selected in F2 progeny by means of allele-specific markers to the VRN-1 genes. To identify genotypes containing leaf rust resistance genes, a microsatellite marker Xbarc232 and primers MF2/MR1r2 and MF2/MR4 specific for T. timopheevii and Th. intermedium translocations, respectively, were used. As a result of hybridization of winter varieties with spring donors, 122 F2 plants were obtained, of which 30 homozygous spring plants with different allelic composition of VRN-1 genes were selected. Of these, 12 plants according to molecular data with Lr -specific primers contained alien translocations. For the comparative analysis of agronomic traits, six F2 plants were used which possessed the same allelic composition of VRN-1 genes as in the initial spring donors but differed in the presence or absence of Lr genes. F3-4 families obtained by selfing of the corresponding F2 plants were studied during two field seasons on the following traits: heading date, productive tillers, grain number per spike, grain weight per spike, and 1000-grain weight. The results of heading date evaluation showed that, despite the same allelic composition of the VRN-1 genes, there was a significant difference in the heading date between F3-4 hybrids and spring donors. Depending on the year of the field evaluation, the differences were three to eight days, and it was found that the presence of alien genetic material does not affect this trait. Analysis of the productivity traits of F3-4 hybrids indicated that the main impact to the manifestation of the traits was made by environmental factors. A significant contribution of the genotype to the phenotypic manifestation of the traits grain number per spike and 1000-grain weight was detected in the hybrid 70-12 containing the translocation from Th. intermedium. The obtained data demonstrated the effectiveness of MAS for the identification of homozygous genotypes with desired traits in the early breeding stages using small sample population. Agronomic trait variations observed in the F3-4 progenies allows to select breeding lines with the optimal expression of valuable traits for further breeding.