Identification Of Tritileymus Germplasm Line And SSR Molecular Mapping Of Its Stripe Rust Resistance Gene

Wheat powdery mildew and stripe rust,caused by Erysiphe graminis f.sp tritici and Puccinia striiformis Westend,respectively, are two damaging and strongly epidemic diseases of wheat occurring around the world. It is a complexity and long work to control these diseaseas. As the new virulence pathogen occurred, many resistant varieties lost their resistance to the two diseases. Screening and identification of new resistance genes are of major importance in enriching the resistant genes resources and enlarging the genetic resistance base in theory and application. Leymus mollis with good resistance to many diseases is the relative of wheat. Interest genes of L. mollis could be transferred using medium materials Octoploid Tritileymus derived from hybridization of wheat and L. mollis. In this research, inoculation assessment, physical and cytological analysis, microsatellite marker techniques were employed in the identification of Shannong0096 and Shannong6343, which were selected from the progenies of Octoploid Tritileymus×common wheat. The main results were as follows:1. Artificial inoculation was carried out on adult plants of Shannong0096 and Shannong6343 to assess their resistance to stripe rust. The mixted stripe rust races included CYR29(Tiaozhong 29), CYR31, CYR32 and shuiyuan46. The susceptible cultivar Huixianhong was also used as check. The results showed that Huixianhong and Yannong15 were highly susceptible, Octoploid Tritileymus and L. mollis were immune, Shannong0096 and Shannong6343 were highly resistant. Identification of the resistance to powdery mildew of Shannong6343 was studied by inoculating with Erysiphe graminis f.sp tritici race 15. The results indicated that L. mollis was immune; Octoploid Tritileymus showed highly resistant or even immune; the check wheat cultivar Mingxian169 and Yannong15 were highly susceptible; Shannong6343 showed excellent resistant. Pedigree analysis suggested the stripe rust resistance of both of the two tritileymus germplasm lines and the powdery mildew resistance of Shannong6343 are all come from L. mollis. 2. The plants of Shannong0096×Huixianhong F1 showed resistant to stripe rust, and the number of resistant individuals and susceptible individuals of Shannong0096×Huixianhong F2 fit a 3:1 segregation ratio, which suggested that the yellow rust resistance of Shannong0096 was controlled by a single dominant gene temporarily named YrSn0096.3. 1283 pairs of wheat SSR markers were used to screen Huixianhong, Yannong15, and Shannong0096, Octoploid Tritileymus, and L. mollis for potential linkage to Yr. Among them, two markers, BARC236 and KSUM134, exhibited special markers BARC236255 and KSUM134245 presented only in resistant parents and donor Shannong0096, Octoploid Tritileymus, and L. mollis. Further PCR test in susceptible and resistant bulks and resistant and susceptible individuals suggested that the two special markers be linked with the YrSn0096. The genetic distance between the resistance gene and Xbarc236-4A,Xksum134 were 5.0cM, 4.8cM counted by software MAPMAKER Version 3.0. Because both of the two markers Xbarc236-4A and Xksum134 were reported on wheat chromosome 4AL, the linkage map and the YrSn0096 resistance gene was located on the long arm of 4A.4. The cytological identification results of Tritileymus germplasm line Shannong6343 was that: The chromosome number in root tip cells was 2n=44, 21 bivalents were observed in most PMC at MI, and the average chromosome configuration was 2n=21Ⅱ, the chromosome configuration (2n=19Ⅱ+ 1Ⅳ) was observed in most PMC of F1 between Shannong6343 and Yangnong15 at MI, the tetravalent presented at a frequency of 24.1%. The two special markers BARC236-4A and KSUM134 screened from the study of Shannong0096 were used to identify Shannong6343 for the reason of the sisterhood of Shannong6343 and Shannong0096. Both of the special markers BARC236255 and KSUM134245 could be stably amplified in Shannong6343. According the identification results on microsatellite markers, physical and cytological study, Shannong6343 was primarily indicated also to be a wheat-Tritileymus reciprocal translocation line.