Molecular Cytogenetic Identification Of Wheat-Rye 1BL·1RS Translocation Line

Wild relatives of common wheat has contained much genetic diversity to improve wheat yield and quality. In order to broaden the genetic base and rich the genetic diversity of wheat, an efficient strategy is to introgress some useful genes of its relatives through distant hybridization and chromosome engineering. At the same time, the breeders have produced many new germplasms with superior characteristics from different genus. Trigeneric hybrids offer the possibility to transfer different alien characters into cultivated wheat to enrich the genetic variation of common wheat. Our research team successfully synthesized the first intergeneric amphiploid (PHW-SA, 2n= 8x= 56, AABBDDNsNs) between bread wheat J-11 and P. huashanica by chromosome doubling of Fi hybrids with colchicine treatment. It has the characteristics of large spike and high resistance to stripe rust. To produce wheat-rye translocations, the F3 progenies derived from the hybrid between hexaploid triticale Zhongsi 828 (2n= 6x= 42, AABBRR) and PHW-SA, with high levels of resistance to stripe rust, high thousand-kernel weight and grain number per spike, were crossed with wheat cultivar SM51, and then seeds selected from the BC2F1 plants were bulked and advanced to the BC2F4 generation by single seed descent. Wheat line K13-868, with enhanced stripe rust resistance, thousand-kernel weight and grain number per spike, was isolated from the BC2F4 generation. The objectives of this work were to determine the chromosome composition of this line using molecular cytogenetic methods, and evaluate its agronomic performance. Main results are as follows:(1) The thousand-kernel weight of K13-868 (53.2g) and grain number per spike (59.9) were significantly higher than that of Zhongsi 828, PHW-SA, SM51, and six other wheat cultivars containing 1BL·1RS translocations. Zhongsi 828, SM51, SY95-71, MN3, MN4, CN16, CM21, CM19, and MY21 were susceptible to stripe rust, showing infection of types 3 or 4, respectively. K13-868 and PHW-SA were highly resistant to stripe rust, showing only 0 infection types.(2) GISH and FISH analyses revealed that the rye chromosome IRS was translocated to the short arm of wheat chromosome 1B in K13-868, and it was a 1BL·1RS translocation line. Similarly, GISH and FISH karyotypes results indicated that six wheat cultivars MN3, MN4, CN16, CM21, CM 19, and MY21 also contained the 1BL·1RS translocation chromosomes.(3) SDS-PAGE analysis indicated that K13-868 contained the 5+10 subunits. The electrophoretic profiles of the gliadin of K13-868, CS and six other 1BL·1RS translocation lines, MN3, MN4, CN16, CM21, CM 19, and MY21, were analyzed. Two rye 1RS-specific gliadin banding patterns that were lacking in CS were present in K13-868, MN3, MN4, CN16, CM21, CM19, and MY21. These results suggested that K13-868 contained the rye IRS chromosome.(4) The amplification products (1000bp and 1500bp, respectively) with the rye IRS-specific markers (co-sec-p1/?-sec-p2 and O-SEC5'-A/O-SEC3'-R) were observed in K13-868, Zhongsi 828, and six wheat cultivars containing the 1BL·1RS translocation chromosome (MN3, MN4, CN16, CM21, CM19, and MY21). No PCR amplification was obtained in the three non-IRS wheat line, including PHW-SA, SM51, and CS. The SSR analysis indicated that two primer pairs, Xwmc230 and Xcfd59 distributed on IBS, didn't amplify the expected bands in K13-868, MN3, MN4, CN16, CM21, CM19, and MY21, but they amplified the expected bands (1500bp and 270bp, respectively) in Zhongsi 828, PHW-SA, SM51, and CS. The results verified that the IBS arm of wheat had been substituted by the IRS arm of rye.