Detection of the Introgression Loci of Synthetic Hexaploid Wheat in Wheat Cultivar Chuanmai 42 by SSR Markers

Triticum durum and Aegilops tauschii are the secondary gene pool of hexaploid common wheat,and their synthetic hexaploid wheat possesses rich genetic diversities and elite genes for common wheat improvement.An elite synthetic hexaploid wheat Syn769(Decoy1/Aegilops tauschii 188) with beneficial traits such as large kernels and high resistance to stripe rust,was crossed and backcrossed with Sichuan commercial wheat cultivars SW3243 and Chuan 6415,and a high yield potential and good stripe rust resistance wheat cultivar Chuanmai 42 was developed.In the present study,217 SSR primers were used to reveal the introgression loci of synthetic hexaploid wheat in Chuanmai 42 by comparing Chuanmai 42 with its parents synthetic hexaploid wheat Syn769,and common wheat cultivars SW3243 and Chuan 6415,and 24 synthetic introgression loci in Chuanmai 42 were detected.The frequency of synthetic introgression loci in Chuanmai 42 was 11.06%,which is significantly deviated from the expected segregation ratio 25%.Distribution of synthetic introgression loci in A,B,and D genomes was unbalanced in Chuanmai 42,with the distribution frequency order of D B A genomes.Unbalanced distribution of synthetic introgression loci among different chromosomes was also observed.Synthetic chromosome fragments were observed most frequently on chromosomes 1B,2B and 5A in Chuanmai 42,while non-loci were detected on chromosomes 1A and 10 others.The result indicated that selection stress was the main reason resulting in the significant deviations of synthetic introgression loci from expected segregation ratios.Significant deviations of the expected allele frequencies in the direction of synthetic hexaploid wheat parent Syn769 in Chuanmai 42 can be used to detect chromosomal regions of interest coming from Syn769.