| Stripe rust, caused by Puccinia striiformis West. f. sp. tritici, Pst, is one of the most serious diseases global wide. Epidemics of stripe rust could be relieved by using resistant cultivars, chemical control and cultivation strategies. As the most economical and eco-friendly method, disease-resistance breeding takes the advantage of the natural and degenerated resistance pool to improve current cultivars. In this study, the rust resistance gene Yr36(also called Wheat Kinase-START1, WKS1), which conferes high temperature and adult plant resistance to wheat stripe rust, was investigated in a Triticeae collection of1,582accessions. Three WKS homologues were cloned and one WKS1from Thinopyrum enlongatum was introduced to wheat cultivar "Bobwhite". In addition, the study investigated the districution of Yr10, Yrl8and Yr36in Chinese wheats and their introgresstion into17major cultivars from Shandong and Henan provinces. The main results are as follows:1. A total of1,580triticeae germplasm including Aegilops comosa, Ae.longissima, Ae.sharonensis, Ae. tauschii, Dasypyrum villosum, Hordeum vulgare, Pesudoregneria gracillima, Thinopyrum elongatum, Th. bessarabicum, Triticum aesticum, T. monococcum, T. dicoccoides, and synthetic wheat were involved in the screening. Both WKS1and WKS2presented in some of the T. dicoccoides accessions, while WKS1alone was detected in Th. elongatum and Th. bessarabicum, and WKS2alone was found in Ae. comosa.2. The retrotransposon insertion identified in the WKS2gene from T. dicoccoides was conserved in all tested T. dicoccoides accessions. Using an ecotilling protocol, the allelic variation of Kinase and START domains were investigated, but no natural variation was identified in the tested T. dicoccoides germplasm, which implied that the WKS genes are highly conserved in T. dicoccoides.3. WKS1homologoues were cloned from Th. enlongatum and Th. bessarabicum, and a WKS2homologoue was cloned from Ae.comosa. TeWKS1and TbWKS1shared99.69%similarity on cDNA level, while they shared98.99%Similarity when compared with the WKS1cDNA from T. dicoccoides. On the other hand, the WKS2cDNAs from Ae.comosa and T. dicoccoides had a similarity of96.34%.4. A plant expression vector cuarrying the Ubi::TeWKS1expression matrix was constructed and was biolistically introduced into wheat "Bobwhite" via co-transformation with the Bar selection plasmid. A total of4,197calli were bombsarded;1,630calli differentiated into seedling on the selective medium;206seedlings were obtained from the Basta selection;119seedlings were positive for the Bar gene, and among them91seedlings were positive for the TeWKS1gene. In Ti generation,87individuals were characterized for the presence of Bar and TeWKS1genes, and three plants were positive for the TeWKS1but negative for the Bar gene.5. Using the functional markers of Yr10, Yr18, and Yr36, a total of652common wheats were screened. Yr10and Yrl8genes were detected in wheat cultivsars from most growing zones. Pedigree comparision revealed that the Yr10and Yrl8genes in Chinese wheat are likely originated from the core breeding germplasm of "Nanda2419". In contrast, the Yr36was absent in all tested common wheat in China. To deploy the known resistance genes, Yr10, Yr18, and Yr36were introgressed into17major cultivars from Shandong and Henan provinces by the marker-assisted selection. Each resistance gene performed differently in the BC1F1generation, but in general the introgression of resistance genes significantly enhanced stripe rust resistance in recurrent genetic backgrounds. |
