Using SSR Distinguish Wheat Nulli-tetrasome & Molecular Mapping Of Powdery Mildew Resistance Gene

In view of uneconomical application of powdery mildew resistance genes at present, we attemp to mark them to facilitate the manipulation of these genes effectively. In the meantime, we explore a way to distinguish nulli-tetrasome using SSRs. 1 Distinguish wheat nulli etrasome using SSR The wheat nulli-tetrasomes are valuable materials in genetic studies,but they are unstable in genetics,so they must be tested before their application. The conventional method to distinguish nulli-tetrasome is time-consuming. Wheat SSRs have specific location of the chromosomes. Using SSR primers to amplify candidate nulli-tetrasome, we can judge whether the nulli-tetrasome is authentic or not by the product .21SSRs located 21 different chromosomes have been used to distinguish a set of nulli-tetrasome .16 of which are true and 5 are false. It was not reported that SSR was applied to distinguish nulli-tetrasome. The detecting system that this study built up can be referrence to others. Excellence of this method is that it is not confined to specific growth periods and specific tissues of the plant. 21 SSRs have been located and 19 locus of them have been assigned to the corresponding chromosomes by using the distinguished nulli-tetrasome. 2 Molecular mapping of powdery mildew resistance gene in wheat Wheat powdery mildew is one of the three diseases in wheat, and it increases year by year. Unfortunately, some resistant sources that are being used loss their resistances gradually, so exploration and application of new resistant sources is a effective method to control the disease of powdery mildew. Wheat landrace Hongquanmang carries a single recessive powdery mildew resistance gene, which is designated privately as PmH.This studies locate PmH on the long arm of chromosome, and two SSR markers WMS61 1, XPSP3O33 link to PmH, which genetic distance to PmH is 5.9cM and 19.1cM respectively. Their locus order on linkage map is XPSP3O33梂MS61 1桺mH. The loci of PmH combined with responses to different powdery mildew strains show that PmH is a novel powdery mildew resistant gene. These results are the basis of marker-assisted breeding and map--base coloning.Pm16, a good powdery mildew resistance gene derived from alien race is resistant to current prevailing powdery mildew. Using AFLP as well as BSA and NILs, a marker linkage to Pm16 is screened. This marker can be used to marker-assisted breeding to Pm16. On the base of the above information some strateges are proposed for screen molecular marker of resistance genes. (ii) In order to guarantee accurate materials, extreme population method can be constructed to screen high resistance gene. (In order to secure polymorphism as high as possible, the two parents of the map population genetic distance must be as far as possible. SSR is used at first when we screen molecular markers, then AFLP. 3 Molecular detecting NIL by means of molecular markers Application of wheat alien race has a potential danger. The NILs consisting of Pm 16 through 7 continuous select breeding appears to resemble backcross parents. In order to value the NILs deeply, AFLP and SSR were used to test these NILs, 4132 polymorphism locus have been tested in two parents, 78 of them are polymorphism in the pedigrees, so NILs and their recurrent parent have similarity of 98.12%. Combined with above information, SSR has higher polymorphism than AFLP, but AFLP has more powerful information.