The Mechanism Studies On Genetic Diversity In Medicago Ruthenica Germplasm Resources

Medicago Ruthenica is an important forage legume and it plays a necessary role in animal husbandry. The genetic diversity of fifty-nine accessions from seven regions was analysed by the phenotypic traits, leaf anatomical characteristic, and three markers techniques to provide scientific basis for the preservation of M.Ruthenica germplasm resources. The results were shown as follows:1. There are significant differences among the variational coefficients of twenty-eight phenotypic traits and nine leaf anatomical characteristic. Leaf area, plant height, number of racemes/twig, number of flowers/Pod, 1000-seed weight, stem color and growth habits were main variational traits in morphology of M.Ruthenica. In addition, palisade tissue thickness, sponge tissue thickness, leaf thickness and vascular bundle diameter also exhibited most variation across leaf anatomical characteristics. The first three characteristics of them positively correlated with annual precipitation (P<0.05), They varied with the changes of precipitation and were closely associated with the drought-resistance of M.Ruthenica2. All of Fifty-nine accessions could be divided into ten groups based on cluster analysis of electrophoresis results of seed storage protein, showing obvious polymorphism among different accessions from different regions. Genetic diversity (h) and Shannon's Information index (I) were estimated as 0.1548 and 0.2744, indicating high genetic differentiations in different groups. Accessions from Inner Mongolia and Tibet showed widely genetic diverse, while the accessions from Beijing did not.3. Fifty-nine accessions were clustered into eight groups according to the analysis of a total of one hundred and fouty-three fragments amplified by eighteen ISSR primer combinations. 80.41% of them were polymorphic. The gene diversity index, Shannon's Information index (I) and genetic differentiation coefficient were 0.3297, 0.4870, and 0.8349, respectively. Genetic diversity of germplasm collected from Inner Mongolia and Tibet was shown very abundant, whereas genetic similarity of germplasm from Beijing was presented very higher. These results were similar to that of seed storage protein.4. Amplified fragment length polymorphism marker analysis was performed on forty-nine accessions with the combination of EcoRI/MseI and four paired AFLP primer. A total of thirty-six bands were amplified and they were all polymorphic, showing 100% polymorphis. All accessions were clustered into eight groups by means of the cluster and principal component analysis. Some accessions from the same region were clustered together or obviously intercrossed.5. Genetic variations and diversities analyzed by three genetic marker techniques including seed storage protein, ISSR and AFLP, differ obviously. For instance, seed storage protein marker can give high genetic diversity among different accessaies. Phenotypic traits, leaf anatomical characteristics and marker techniques are available to analyzed the genetic diversity of M. Ruthenica germplasm, but seed storage protein and ISSR are most suitable marker techniques. The main results in this paper were summarized as follows: (1) There were abundantly intraspecies and interspecific genetic diversities in M. Ruthenica germplasm resources and intraspecies diverse was very higher than interspecies diverse; (2) The genetic diversities of M. Ruthenica germplasm from different regions differed significantly. Accessaries from Inner Mongolia showed higher genetic diversity than that from other regions; (3) Different clustering vines result from different genetic marker techniques. However, accessions from the same regions or similarly geographical environment could be clustered together, showing the accessions from the same geographical sources with closed relationship; (4) That Phenotypic traits, leaf anatomical characteristics and marker techniques are suitable for the analysis of the genetic diversity of M. Ruthenica germplasm will provide the scientific basis for the preserve of M. Ruthenica germplasm resources.