The Research About Structural Analysis Of Population Genetic And Way Of Genetic Mapping Construnction Of M.truncatula

Medicago Linn is an important species of forage grasses, among which perennial alfalfa is called"the king of the forage grass, it's important to study genetic relations of medicago Linn germplasm resources. Annual Medicago , following Arabidopsis and rice, was the third kind of plants sequenced completely. It is similar to legume species in terms of gene , especially M.truncatula, and the information from M.truncatula can be used for the other legume species, which has important meaning to excavate the genetic resource of legume species and improve breeding of legume species and alfalfa. In the study, 38 kinds of perennial and annual alfalfa underwent analysis of genetic diversity by SSR marker. With the major gene +plus polygene model of quantitative traits, a joint analysis of multi-generations from the cross between A20 and A17 was carried out to investigate the inheritance of the length of the lateral branches, and used SSR marker to construction the genetic map. The major results were as follows:1. By 33 nuSSR markers and 28 chloroplast microsatellites(cpSSR), the genetic diversity and genetic relationship of 38 species of medicago Linn was screened, obtained 464(nuSSR),422(Average) polymorphic alleles richness(∑Aij). In 38 species of medicago Linn, the average alleles of 28 chloroplast SSR markers is higher than 33 nuclei SSR markers, genetic diversity Index is opposite. The total alleles, average alleles, diversity levels of perennial medicago were lower than annual medicago. The result of thrice clustering for 38 species of medicago Linn using 33 nucleus SSR, 28 chloroplast SSR and 61 locus is: three clustering separated all materials into two types: annual medicago and perennial medicago. Accessions of annual medicago was the more genetically diverse and contained larger number of regional special alleles than perennial medicago.2.With the major gene plus polygene model of quantitative traits, a joint analysis of multi-generations from the RILs population cross between A20 and A17 was carried out to investigate the inheritance of the length of the first lateral branches and length of main stem, the result of joint analyses of P1,P2 and RILs generations of A20×A17 showed the first lateral branches was controlled by two major genes and polygene mixed inheritance model, E-1-5 model. The inheritance model of the first lateral branches was the F-2 model and the inheritance model of the main stem was the B-2-6 model. Heritability of major genes of RILs population on the first lateral branches , the node of the first lateral branches, the main stem , the ratio of length and width of true leaf and leaves were estimated as 61.4%,81.3%,1.96%,87.90%and 61.20% respectively, and heritability of polygene was estimated as -30.0%,-15.0%,-211,-1.70%and 22.30%. Heritability values of the major genes of RILs population was much higher while their polygene was lower.3. 157 individuals of RILs populations, consisting of A20 and A17 from Jemalong of medicago truncatula as linkage map, formed 10 SSR genetic map of medicago truncatula. 10 marker loci among 21 makers showing separation made up three linkage groups, including 5, 2, 3 makers separately, and the total length of linkage groups was 140.3cm with an average distance of 14.03cM each other. The length of linkage groups was 88.1cm, 35.7cm and 16.5cm separately, and the longest one was 88.1cm.