The Genetic Diversity Analysis Of 109 Sweet Potato Varieties By Isozyme Electrophoresis

Sweet potato is one of the major crops in our national products, recently, with the acting of exploiting to the value of the sweet potato in foods ,medicine, industry and feedstuff , more and more attention has been paid to the breeding. While to make clear of the relations in sweet potato varieties, and to research their genetic diversity is very important to the breeding. In this paper, four isozymes (superoxide dismutase (SOD), esterase (EST), polyphenol oxidase (PPO) and Amylase (AMY)) of 109 strains sweet potatoes form CQ sweet potato research center were studied. and made the best use of the digital recording to establish the clustering dendrogram of the 109 sweet potatoes, and had made clear of their relationship.The results showed that among these isozymes, SOD isozyme had middling polymorphism and conservation characteristic, and cluster analysis showed that no obvious differences among some varieties, which indicated that it is not sufficiency to identify these sweet potatoes only according SOD isozymes; The zymograms of EST isozyme are very abundant, this reflected favorable polymorphism and certain conservation characteristic, some varieties must be identify in a relative small distance when use cluster analysis; PPO isozymes had sufficiency bands and extremely polymorphism; While AMY isozymes can't form clear bands, so it isn't suitable to sweet potato isozymes analysis. To summarize the results, the study showed that it is not sufficient to analysis multitudinous isozymes only according describe the percentage of the polymorphism sites.Through the general cluster analysis of the three sweet potato isozymes indicated that the bands are very abundant, and had favorable polymorphism characteristic. Among the three zymograms, there are 32 bands identified, in which 3 bands are in common, loci ( P) covered 90.6%; The incidence of the high frequency bands beyond 80% has 10, which covered 31.3% of the total. 5 bands frequencies were ranged from 30% to 80%, covered 15.6% of the total. 17 are below 30%, covered 53.1% of the total. This indirect indicated that inherit variances of sweet potato are very enrich in Chinese local populations, and supports the hypothesis that China was the secondary center of sweet potato diversity. The cluster analysis results showed that there is certain comparability genetic basis of the sweet potato which Stem from China; Domestic seeds not only has obvious genetic diversity, but also appears obvious association; The variety from America has long genetic distance, so has favorable polymorphism and breeding value; The most varieties from Japan gather independently, so their relationship is near.This study had described the clustering dendrogram and genetic similarity matrix of "Yushu 303" and related species, which can offer theoretical foundation for the breeding and others based on "Yushu 303".Moreover, this study established an efficient, exact and intuitionistic method of zymogram recording through analysis a great deal of sweet potatoes, which made it easy to use biological software to analysis the results, Meanwhile, it's also propitious to establish zymogram database, offer experiences and references to other researchers.