| Wheat stripe rust caused by Puccinia striiformis, is a prevalent and destructive disease to the worldwide wheat production. China is a country with massive people, and wheat is one of the most important grain ration. Wheat stripe rust also contribute to huge yield losing. Chinese wheat stripe rust epidemic system is much more complicated, as the fungal pathogen has two regions to overcome the adverse weather:overwintering zone and oversummering zone. It is difficult to block the route of transmission from space and time. As a consequence, little effect did the prevention and control work achieved. Many researchers have proved that the most effective way to control wheat stripe rust is breeding resistant cultivars and seek for new resistant gene resources. We should constantly discover new resistance genes to cope with the new mutants virulent races. All previous pandemic of wheat stripe rust made it clear that we can no longer just promoting a few series of wheat, but to diversify the main cultivars and enrich the resistance gene resources. The reaearch on wheat stripe rust is somehow an endless fight.Previous research by SSR molecular marker, had located the new stripe rust resistance gene YrL693 on the wheat 1B chromosome, and screened several linked SSR markers. However, the markers are not enough, we need more markers based on other technique for further encryption.The mapping population for this study is based on the offspring F2 and F2:3 family which generated from the hybridization between resistant parent L693 and susceptible parent L661. Though literature review, we collect EST markers reported on the wheat 1B chromosome. More EST markers should be designed all by ourselves. We download the EST resources on the wheat IB chromosome from the GrainGene website for EST-STS marker designing. Then use these markers for polymorphism screening. Combine the sequence of linked EST with B. distachyon, rice and sorghum genome to identify the collinear regions of these three wheat related genus. The results are as follows:1. Generated from the hybridization between resistant parent L693 and susceptible parent L661, the offspring F1 are resistance to stripe rust. The followed generation F2 emerge resistant and susceptible separation. Using the chi square test, it accord with a ratio of 3R:1S. Resistant and susceptible separation also appear at the lines of F2:3 family, accord with a ratio of 1R:2H:1S. It indicate that the yellow rust resistance traits on L693 is controled by a dominant gene. We temporarily designate it as YrL693.2. Previous work has already located the YrL693 on wheat 1B chromosome through SSR marker technique. This study adopts EST molecular marker technology to further encrypt the genetic map. PCR amplification and polyacrylamide gel electrophoresis are subjected to detect the genomic DNA of the F2 generation. Then, we screening 8 pair of linked EST-STS primer:CD77, WE 173, WE201, BE443300, BE518403, BE444094, BE404005 and BE405692. In the construction of genetic linkage map, theirs location are: 1.186 cM,0.118 cM,1.011 cM,0.758 cM,0.853 cM,0.937 cM,0.948 cM and 1.282 cM. Among them, BE443300 and BE444094 marker genotype are in accord with the ratio of 3:1, the rest markers’genotype are in accord with the ratio of 1:2:1.3. We use the 8 screened EST markers together with the YrL693 co-segregated EST marker LS36 which reported by Rao hefei for comparative genomic analysising with B. distachyon, rice and Sorghum. Comparative genomic analysis established the collinearity of the YrL693 genomic region with a 2.22 Mb (Bradi3g2616-Bradi3g27877) region in B. distachyon chromosome 3,3.49Mb (Os10g0396400-Os10g0456500) region in rice chromosome 10 and 8.12Mb (Sbolg020230-Sb01g023110) region in Sorghum chromosome 1. The collinear sequence will be supposed to provide a reference for the analysis of candidate gene. |
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