Stripe Rust Resistance Gene Of Genetic Analysis And Molecule Marker Mapping In Common Wheat

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most devastating diseases in common wheat worldwide. Deployment of resistant cultivars is the most environmentally friendly and economical way for controlling the disease. Identification of stripe rust resistance genes and their closely linked molecular markers could lead to a more efficient strategy in wheat breeding for durable resistance to stripe rust.In the present study, genetic linkage map was constructed in two F2 populations derived from the crosses of Jimai22/Avocet S and Ji965261/Chinese Spring using simple sequence repeat (SSR) markers. These F2 populations along with F1 and their respective parents were planted in greenhouse under controlled conditions and inoculated with the prevalent Chinese Pst race CYR32. The results were summarized as follows:In the seedling tests with CYR32, Jimai22 were immune (IT=0) and Avocet S were susceptible (IT=3"-4). Fifteen F1 plants were immune (IT=0) to CYR32. In the F2 population,218 plants were resistant (IT=0-2+) and 81 plants were susceptible (IT=3"-4) to CYR32 (x23:1=0.697, df=1, P=0.4039). This result indicated that the stripe rust resistance of Jimai22 was controlled by a single dominant gene, temporarily designated YrJ22. Bulked segregant analysis (BSA) with SSR markers in Jimai22/Avocet S population revealed that YrJ22 gene was located on chromosome 2AL, closely linked to four SSR markers, Xcfd5O, Xwmc658, Xgwm382 and gwm311 on chromosome 2A. The Xwmc658 is a closely linked marker to YrJ22 with a genetic distance of 1.9 cM. Xgwm382 and Xgwm311 are present at the same position with a genetic distance of 2.5 cM to YrJ22. Xcfd50 is linked to YrJ22 with a genetic distance of 5.1 cM. Currently, The known stripe rust resistance gene Yrl and Yr32 were located to chromosome 2AL. The test of Jimai22 and the lines with Yrl Yr32 using 26 Pst races indicated that YrJ22 is different from the known stripe rust resistance genes Yrl and Yr32.In the seedling tests with CYR32, Ji965261 were highly resistant (IT=0), and Chinese Spring were highly susceptible (IT=3-4).14 BC1 plants,9 resistant and 5 susceptible (x21:1=1.1429, df=1, P=0.285) varied from highly resistant to susceptible (IT=0;-3) to CYR32. In the F2 population,246 plants were resistant (IT=0-2+) and 101 plants were susceptible (IT=3-4) to CYR32 (x23:1=3.121, df=1, P=0.0773). Results obtained from the F2 populations indicated that the stripe rust resistance of Ji965261 was conferred by a single dominant gene, temporarily designated YrJ965261. Four markers, viz, Xgwn582, Xbarc8, XH20 and XAF1-4, showed polymorphisms between two parents, and between the resistance and susceptible bulks in Ji965261/Chinese Spring population. Linkage analysis indicated that the resistance gene YrJ965261 was located on chromosome 1BL, closely linked to the four markers with genetic distances from 0.5 cM to 2.0 cM. YrJ965261 was flanked by four makers and the closest flanking markers were XH20 and XAF1-4, and Xbarc8 with genetic distances of 0.5 cM and 2.0 cM, respectively. YrJ965261 gene with marker Xgwm582 is cosegregationo YrJ965261 is different other strip rust resistance gene on 1BL chromosome. It was confirmed that YrJ965261 is different from Yr9 on chromosome 1B/1R in the test of the lines with Yr9 using 26 Pst races.