| As the model legume, Medicago truncatula are the third plant to have its genome completely sequenced after Arabidopsis and rice. M. truncatula have the genetic comparability with the mostly crop legume species, especially M. truncatula and alfalfa are the closely relative crop species and their genome have highly homology. So the information from M. truncatula can be used for the other legume species, this is very important to excavate genetic resource of our country and improve the breeding of the crop legume species and alfalfa. This study identified and filtrated the germplasm of the annual medicago using agronomic character and SSR marker and selected a pair of parent of the M. truncatula W5160 and Jemalong that have remarkable difference between them. Then hybridized W5160×Jemalong and constructed F2 population of the medicago truncatula. With the major gene plus polygene model of quantitative traits, a joint analysis of multi-generations from the cross between W5160 and Jemalong was carried out to investigate the inheritance of the legenth of the lateral branches. The major results showed as follows:1. SSR-PCR reaction system that adapted to the model legumes medicago truncatula and annual medicago were optimized with orthogonal design and completely randomized design. The results showed that the optimal SSR-PCR reaction system was 1U TaqDNA polymerase, 0.20mmol/LdNTP, 2.0mmol/L Mg2+, 1.5μmol/L primer and 20ng/μL DNA in the total volume of 10μL. This reaction system was validated by identification of hybridization of M. truncatula and identifing germplasm of the annual medicago.2. Identifing cross from W5160×Jemalong based on SSR marker. The results showed that F1 cross contained mother genotype and father genotype, so this cross was heterozygosity.3. Hereditary divergence of the 19 annual medicago germplasms from different resource were identificated by optimized SSR reaction system and genetic similarity were clustered using the UPGMA. The result showed that SSR polymorphic have distinct difference and ample genetic diversity. Jemalong,DZA and Caliph have remarkable difference. Among medicago lupulin,medicago scutellata and medicago truncatula,medicago scutellata have closely relative with medicago truncatula and similarity coefficient is 0.62, however, medicago lupulin have farther relative with medicago truncatula and similarity coefficient is 0.32.4. With the major gene plus polygene model of quantitative traits, a joint analysis of multi-generations from the cross between W5160 and Jemalong was carried out to investigate the inheritance of the length of the latheral branches. In the inheritance analyses of the length of the latheral branches, the results of joint analyses of P1,P2,F1and F2 generations of W5160×Jemalong showed that the first and the second latheral branches inheritance was controlled by two major genes and polygene mixed inheritance model and the seed yield. The inheritance model of the 100-pod weight is the E-4 model and the inheritance model of the above-ground biomass is the E-1. Heritability of major genes of F2 population on the first and the second lateral branches,the seed yield, the 100-pod weight and above-ground biomass was estimated as 89.06%,82.24%,91.9%,43.1% and 61.8%, respectively, and heritability of polygene was estimated as 7.44%, 14.45%, 4.1%, 43.3% and 25.8%. The results showed that the inheritance of five traits fitted two major genes plus polygene model. Heritability values of the major genes of F2 population were more higher while those polygene were lower. In the improvement of breeding of the alfalfa, accumulating polygenes should be emphasized, while utilization of major genes is preferred. |
