Study On Genetic Diversity Of Alfalfa(Medicago Sativa L.) Germplasm In China

The relationship between genetic variance and evolution and distributing of alfalfa germplasm in morphological, protein and DNA levels are studied by morphological, allozymes and AFLP technics using 40 accessions which come from main growth areas in northern China as objects and 34 accessions including American, Australian and France materials as checks. A primary result was obtained in the field of alfalfa genetic diversity in China.Abundant genetic variance is found in alfalfa germplasm of China through research on the morphologic traits. And the intra-variance is larger than the inter-variance of the alfalfa population of China. The trait with the largest variance is euphylla height (EH), whose coefficient variance (C.V) is 26.40%, and the coefficient variance (C.V) of the Ratio of leaf Length and leaf Width (L/W) is above 10%( 14.26%). Multi-comparison indicated that all the variance levels have significant correlation among the studying traits except leaf width and branch amount of individual plant (BAP). Main component analysis indicated that the height and leaf length made up of the first component, and they play a important roles in the total morphological variances.Through the starch gel electrophoresis of four different allozymes as LAP, EST, PGM and MDH, 9 locus and 28 co-dominant alleles were found in all 22 alfalfa accessions. According to the genetic law of the zymogram of mornomeric and diameric enzyme in the quadploid plant the allele frequencies in polymorphic loci were statistically analyzed. The allozyme data indicated that in all examined loci, the polymorphic loci percentage is 74.07%. The range of allele frequencies is 0.788~0.003, and the average allele number in polymorphic loci is 2.73, which is much higher than the foreign check cultivars (0.785~ 0.002 and 2.43) .For the first time the genetic diversity of 40 alfalfa (Medicago sativa L.) populations distributing around 12 province of China is analyzed using AFLP technique. The result showed that the polymorphism is in a high level in China alfalfa populations. We have selected total 177 bands by 4 pairs of primer combinations, as E35/M5O, E35/M49, E38/M62 and E40/M47, which 97 are polymorphism bands. The average of each pair of primer combinations has amplified 44.3 bands. The percentage of polymorphism band is 54.8%. The genetic distance range of alfalfa population of China is 0.548-0.802. Cluster analysis showed that populations with a close origin and similar distributing area could get a prior clustering.