Study On Ploidy Level And Genetic Diversity Of Medicago Falcata L.

Medicago falcata L. widely spreads in temperate grassland, which has many better traits than other Medicago species. Medicago falcata L.is an important genetic resource for alfalfa breeding. It is the preferred forage plant in improving degraded grassland and developing artificial grassland.In recent years, with the rapid development of alfalfa industry in china, it is urgent need to cultivate high yield, good quality, strong resistance and wide adaptability of alfalfa cultivars. Therefore,It has important significance to breed quality variety. Forty-seven Medicago falcata L. materials were used in this study, and they were supplied by Institute of Animal Sciences, Chinese Academy of Agricultural Sciences. The research aims to detect the chromosome ploid level of Medicago falcata L. by flow cytometry, and then study genetic diversity by SSR molecular marker. The results were as followed:1In the case,"Medicago sativa L. cv. Alfalfa queen" is the tetraploid by counting the number of root chromose, which is used as the standard material in flow cytometric analysis. The principle of flow cytometry analysis is compare relative nuclear DNA content of tested material with the one of standard material. Flow cytometry analysis indicates that07P331、07P3325and05185are the diploid(2n=2x=16),and another forty-four materials are the tetraploid(2n=4x=32).2The nuclear DNA content of Medicago sativa L. cv. Alfalfa queen" is1.92pg/2c standarded by Gallus sp. Flow cytometry analysis indicates that the DNA content of diploid accessions are ranging form0.960pg/2c-1.032pg/2c, the genome sizes are469Mb to505Mb; the DNA content of tetraploid accessions are ranging forml.718pg/2c-2.108pg/2c,the genome sizes are840Mb to1031Mb,this value is almost the double of diploid.3The CV (coefficient of variance) is≤10%in the research, and the value of diploid is less than the tetraploid. We also make the simple discussion about flow cytometric method.4Ninety-six primer pairs were screened on a panel of6Medicago falcata L. materials. Fifty-six primer pairs can produced polymorphic amplification profiles. There were347alleles detected, the allele numbers of each primer ranged form3to9, with an average of6.2.The PIC values of these56markers ranged from0.5694to0.8689with the average value of0.7679.5Twelve polymorphic SSR primer pairs from eight alfalfa linkage groups were used to evaluate the genetic diversity of47Medicago falcata L. accessions. There were162alleles detected, with an average of13.5. The Mean Heterozygosity ranged from0.108to0.267. Higher PIC values were observed, and values ranged from, with0.7841-0.9242,a mean of0.8780. The average PIC and He of Medicago falcata L. coming from overseas are0.8615and0.234, that are larger than nationes PIC(0.8231)�'�He(0.186). PIC values ranged from0.7021to0.7829,the order were:Russia> Ukraine> Inner Mongolia> Xinjiang>Liaoning> Tibet. The Mean Heterozygosity ranged from0.116to0.315,the order were:Xinjiang>Ukraine>Inner Mongolia>Liaoning>Russia>Tibet.6Forty-seven Medicago falcata accessions was seperated into three different groups (Ⅰ, Ⅱ and Ⅲ) with the method of UPGMA. Seventeen accessions come from Russion were clustered into group Ⅰ.Group Ⅲ has only an accession(CHQ117), which is come from Sichuan. The remain29materials were clustered into group Ⅱ.The genetic similarity coefficient (GS) values ranged from0.000-0.667, with an average of0.329.The result of principal components analysis was agree with the result of UPGMA, and Forty-seven Medicago falcata accessions was clustered into three different groups by principal components analysis.