Inheritance Of Stripe Rust Resistance Gene And Identification Of HMW-GS In Thinopyrum-derived Wheat Breeding Lines

The ongoing improvement of wheat cultivars is dependent on a continuous supply of genetic variability. The Thinopyrum species, Th. intermedium (2n=6x=42) and Th. ponticum (2n=10x=70) both carry many useful agronomic traits. Partial wheat-Thinopyrum amphiploids are potential tertiary gene pools for wheat improvement. An attempt was made to transfer resistances to powdery mildew and yellow rust into wheat from Th. intermedium and Th.ponticum, and many multi-resistance lines including CH7103 have been developed by crossing susceptible wheat cultivars with resistant partial amphiploids as donor parents. The objectives of this study were to determine the inheritance of stripe rust resistance gene introgressed from Th. ponticum in wheat line CH7103 and its allelism with known resistance genes, Yr5, Yr10, Yrl5 and Yr41, for resistance to a prevalent and most widely virulent race CYR32 in China, and to analyze the compositions of high molecular weight glutenin subunits (HMW-GS) in ninety-three Th. intermedium-derived lines. The results are as follows:1. CH7103 is a wheat multi-resistance line developed recently from crossing susceptible wheat cultivars with Thinopyrum ponticum-derived resistant partial amphiploid Xiaoyan7430 as donor parent. In this study, the evaluation of resistance reactions demonstrated that CH7103 and its donor Xiaoyan7430 as well as the wild parent were resistant at the seedling and adult stages to CYR31 and CYR32 of the prevalent and most widely virulent in China, whereas all the wheat parents involved were susceptible, indicating that the stripe rust resistance in CH7103 was possibly derived from Th. ponticum. Genetic analysis of the F1,F2, F2:3 and BC1 populations from stripe rust resistant line CH7103 revealed that a single dominant gene was responsible for the adult resistance to CYR32. The allelism tests of four F2 populations demonstrated that the stripe rust resistance gene in CH7103 was likely different from the known resistance gene Yr5, Yr10, Yrl5 or Yr41. The cytological observation showed that the somatic chromosome number of CH7103 and its F1 hybrids involving T. aestivum cv. Chinese Spring and Taichang29 was 2n=42, and their most pollen mother cell had a regular pairing of 2n=21Ⅱat meiosis, suggesting that this resistant line was a stable cytological cryptic alien introgression with being largely identical to the chromosome constitution of breed wheat.2. Using SDS-PAGE technology to analyze the compositions of HMW-GS in 93 wheat lines from the cross of common wheat with Th. intermedium-derived partial amphiploid TAI7045, then to use PCR-based markers for confirmation of Aχ2*, Dχ5, Dy10, Bχ14, Bχ17, at Glu-Al, Glu-Bl and Glu-Dl loci, respectively. The SDS-PAGE results showed the proportion of high quality subunits was relatively smaller and ten kinds of allelic variation at site Glu-1 in lines tested. Among them, the N type was main in N,1,2* encoded at Glu-Al; the frequency of 7,17+18 type was high at Glu-Bl loci; and 2+12 was the main type of glutenin subunits at Glu-Dl. A total of eleven kinds of HMW-GS combination types were detected and the frequency of subunit compositions N,7,2+12 and N,17+18,2+12 was higher. Three lines had excellent quality subunits at 2 encoding loci, account for 3.3%, and five lines had excellent quality subunits at 3 loci, account for 5.4%. The quality scores of eight lines were 8-10, account for 5.4% of all the tested genotypes. The results of PCR-based markers identified the frequency of Ax2*, Dx5, Dy10, Bxl4 and Bxl7, which were consistent with those of SDS-PAGE analysis.