Analysis Of Longdong Wild Alfalfa Using Isozymes And Ssr Markers

Longdong wild alfalfa (Medicago sativa L.cv.Qingshui) is a rhizomatous perennial autotetraploid forage legume found in the Qingshui, Gansu, which has potential as forage because of its high branching ability, presence of rhizomes and its tolerance to trampling, cold and drought. Longdong wild alfalfa differs from cultivated alfalfa so could represent an important extension to alfalfa germplasm. Isozymes and SSR markers were used to evaluate the genetic relationship among Longdong wild alfalfa and cultivars.(1) The genetic relationship of Longdong wild alfalfa and other 37 cultivars were analysed using five isozymes (peroxidase, amylase, catalase, esterase and superoxide dismutase). The results showed that five isozymes of 38 accessions had 41 isozyme bands, five of which were only presented on zymogram of Longdong wild alfalfa. Similarities among 38 accessions varied from 0.583 to 1.000, the similarity between Longdong wild alfalfa and other cultivars varied from 0.583 to 0.833 which were much lower than between the cultivars (0.625 to 1.000). Cluster analysis indicated that 38 alfalfa accessions can be divided into two major groups at the similarity value of 0.622, Longdong wild alfalfa was clustered in an independent group, which was in agreement with the results from principal component analysis.(2) The genetic relationship of Longdong wild alfalfa and other 41 cultivars were anylyzed using SSR markers. A total of 231 alleles were detected using 15 primer pairs, the allele numbers of each primer pair ranged from 12 to 22, averaging at 15.4. The polymorphic index content (PIC) values ranged from 0.846 to 0.938 averaging at 0.909. The similarity between Longdong wild alfalfa and other accessions varied from 0.636 to 0.790 with an average of 0.709 which were much lower than between the cultivars (0.720 to 0.831). According to cluster analysis, 42 alfalfa accessions were clustered into 3 groups at the similarity value of 0.749, among which Longdong wild alfalfa was clustered in an independent group, which was in agreement with the results from principal component analysis (PCA).The results of both isozymes and SSR markers showed that Longdong wild alfalfa has distinct relationship with alfalfa cultivars, and can be regarded as distinct alfalfa germplasm, with the potential to broaden the genetic basis of cultivars developed by breeding programs. The genetic relationship among the 42 examined alfalfa accessions could be useful for alfalfa introduction and the selection of suitable and potential parents for future alfalfa breeding programs.