RAPD And ISSR Analysis In Genetic Relationship Among Varieties Of Sweetpotato

Ipomoea bataas(L.) Lam. is an important crop and it is in the 4^th place of crop in China. Cultivating fine sweetpotato cultivars of high yield,high quality, strong adversity and easy to store is the first measure to realize the sustainable development of the sweetpotato production. And it is also the long-term objectives of sweetpotato breeding workers. Analysis of genetic diversity of sweetpotato is an dispensable link of sweetpotato breeding.In this paper, the technique of RAPD and ISSR molecular markers was used to study genetic diversity of 28 good sweetpotato cultivars, and to analyse their genetic relationship. The purpose is to provide a basis for sweetpotato hybridization.This paper optimized the reaction system of RAPD and ISSR fitting for analyzing the genetic diversity of sweetpotato. And 15 and 9 RAPD and ISSR primers were respectively chosen for they showed strong, reproducible amplification and distinct polymorphisms from 43 and 30 primers. The results were as follows:1. 15 RAPD primers generated 124 bands,of which polymorphic bands number was 60, the percentage of polymorphism equaled 48%;9 ISSR primers generated 69 bands, of which polymorphic bands number was 65,the percentage of polymorphism equaled 94. 2%. Any amplified band was reguarded as a character, and the binary data matrix was set out according as the bands existed or not.The Jaccard coefficient was worked out by using DPS software. The result of genetic similarity analysis for 28 sweetpotato cultivar genotypes showed that the RAPDs and ISSRs Jaccard coefficient respectively ranged from 0. 6696 to 0. 9535 and from 0. 3333 to 0. 7609, suggesting that ISSRs were better than RAPDs to analyzing the genetic diversity of sweetpotato.2. According to the clustering analysis of RAPD and ISSR's results, 28 sweetpotato cultivars were divided into 4 groups. Jinshan 57,Jinshan291, Jinshan696 and Zhel257 were clustered into one section, Huangjinqianguan and ST1-6 were clustered together, Guangshu99-104, Xushu2-2 and Xiangshu75-55 were clustered into one section and Longshu1, Fushu2 and Jishu98 were clustered together. Thus, identification of genetic relationship of these cultivars were considered as being reliable. And according to the comprehensive cluster results of these two molecular markers, 28 sweetpotato cultivars were divided into 3 groups.The research proved that RAPD and ISSR molecular markers could reflect the genetic differences and the genetic diversity among all sweetpotato cultivars. Also it discussed the analyses of technologies as well as systems of RAPD and ISSR, providing some suggestions for the sweetpotato breeding of disease-resistant and high-starch.