Inheritance Analysis For Resistance To Stripe Rust And Molecular Mapping Of A Gene For Resistance To Stripe Rust In Wheat Variety PIW138

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most destructive diseases in common wheat (Triticum aestivum L.), and it occurs severely and widely in China. Puccinia striiformis is a specific fungus on wheat and its sexual stage has not yet been found. Therefore it is the only method to use host resistance genes to identify the pathogens'virulent genes. After finding out the genetic characteristics, markers and chromosome localization of stripe rust resistance genes, we can improve research levels of pathogens'specificity and host resistance gene analysis.PIW138 variety introduced from Pakistan has good agronomic characters and excellent resistance to disease. In this study, inorder to find out the genetic characteristics of the PIW138 variety and made the linked map with the SSR makers which are favourable to select the resistance Puccinia striiformis f. sp .tritici of wheat and screen the genes of resistance to strip rust. The resistant (BR) and susceptible (BS) bulks ware maked according to the bulked segregation analysis (BSA) method. Tatcher, as maternal parent, was crossed with PIW138, as paternal parent, to obtain F1 seeds. F1 plants were self-pollinated to obtain F2 seeds. F1 and F2 populations were inoculated with Chinese pst isolate CYR32 in the greenhouse for the identification of seedling resistance gene in PIW138。A total of 200 SSR primers were used to test the parents as well as resistant and susceptible bulks. The polymorphic SSR markers between the resistant and susceptible bulks were used for genotyping the F2 populations. Linkage analysis was conducted with the software MapManager QTX b20 and the genetic linkage map was drawn with the software Mapdraw.1 Through identification the resistance of wheat seedlings against stripe rust and inheritance analysis for resistance to stripe rust,indicate that PIW138 has a resistance gene which resistant Puccinia striiformis f. sp. tritici race CYR32. All the F1 plants and PIW138 display a high level of resistance. The segregation of resistant and susceptible F2 plants inoculated with CYR32 indicates that single dominant gene determines the reactions of PIW138 line which fits the segregation ratio of 3R:1S and temporarily designated as YrP138.2 Total 200 SSR primers were screened, and four SSR markers Xwmc52, Xbarc61, Xgwm268 and Xgwm153 on the chromosome arm 1BL were found to be polymorphic between the resistant and the susceptible DNA bulks as well as their parents. Genetic linkage was tested on segregating F2 population with 259 plants, including 193 resistant and 66 susceptible plants. All four SSR markers were linked to the stripe rust resistance gene in PIW138. The genetic distances of Xwmc52, Xbarc61, Xgwm268 and Xgwm153 to the resistance gene were 29.8 cM, 6.2 cM, 6.8 cM and 8.2 cM respectively.3 At the present, only Yr5, Yr10, Yr15, Yr24, and Yr26 which located at the chromosome 1B among the officially reported Yr genes are effective against race CYR32 in China. Based on the reaction patterns and chromosomal locations, it can be concluded that YrP138 is different from Yr5, Yr10, Yr15, Yr24, and Yr26 and is probably a novel stripe rust resistance gene.