Chinese Sweet Potato (ipomoea Batatas) Varieties Genetic Diversity And Molecular Identification

Ipomoea batatas (L.) Lam., belonging to Ipomoea of Convolvulaceae, is a perennial or annual trailing herb. It initially originated from South America, and now it is widely distributed in tropical and subtropical and template regions of the world. Asexul reproduction can be carried out by root and stem. It can be planted in the four seasons and it doesn't choose soil. It has high and stable yields, wide adaptability and strong regeneration. It is rich in nutrition and its roots, stems and leaves can be edible, so it is an important crop and it is in the 4th place of crop in China. But high heterozygosity on heredity and interspecific and intraspecific hybridization incompatibility, which wildly exsisted, gravely limit its production and development. It is still urgent to cultivate fine sweetpotato cultivars of high yield, high quality, strong adversity, nonvirus and easy to store.In this paper, the technique of RAPD molecular markers was firstly used to study genetic diversity and molecular identification of 50 native and abroad sweetpotato cultivars from Shandong Agricultural Acadamy of Science and Xuzhou Sweetpotato Research Center, and to analyse their genetic relationship and germplasm resourses in order to offer theoretical foundation for identification, selection, and hybridization breeding.In order to select a set of suitable primers, 3 cultivars were initially surveyed with 386 10-base primers.24 were chosen for they showed strong, reproducible amplification and distinct polymorphisms from 386 10-base arbitrary primers, and a total of 157 DNA fragments were amplified from 100bp-3500bp, among which 91 were polymorphic, and which accounted for 58%. The average number of DNA band produced by each primer was 6.54. 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 NTSYS-pc software. The result of genetic similarity analysis for 50 sweetpotato cultivar genotypes showed that Jaccard coefficient ranged from 0.496 to 0.930, suggesting that there was a close genetic relationship among them and a rich genetic polymorphism among the sweetpotato cultivars due to the Jaccard coefficient. A DNA molecular dendrogram was established for 50 sweetpotato cultivars genotypes based on UPGMA (unweighed pair-group method with arithmetic mean) cluster analysis of the 157 DNA bands amplified by 24 primers. According to the coefficient and the cluster result, when the coefficient is 0.70, these cultivar genotypes were divided into 4 groups: Group A, Group B, Group C, Group D. when the coefficient is0.75, these cultivar genotypes were divided into 14 sections. The coefficient in each section all surpasses 0.75, which suggests that the relationship among sections was fairly near, but some genetic difference exists.Group A was divided into section Al and A2. Group B was divided into section Bl and B2. Group C was divided into section Cl, C2, C3, and C4. Group D was divided into section Dl, D2, D3, D4, D5, and D6. Al included 3 genotypes, viz., 470042, Nanfang, Shengnan. A2 only included 1 genotypes, viz., No.6 Yanshu. Bl included 5 genotypes, viz., No.2 Jishu, No.2 Lushu, Huabei 52-45, No.8 Qingnong, Xu 236. B2 included 4 genotypes, viz., Nanjing 92, No.5 Jishu, No.3 Luohong, No.4 Xushu. Cl included 4 genotypes, viz., 460188, Lizixiang, Xu 941, NO.l sushu. C2 included 6 genotypes, viz., Xu 1-2, Yiwohong, Xinzhonghua, No.l Zheshu, Ningyuansanshirizao, Wanshu 596. C3 included 6 genotypes, viz., 460103, 460027, Ji'nanhong, Nanjing 51, Yubeibai, No.l Shanshu. C4 included 5 genotypes, viz., No.8 Yanshu, Anshu 07, Shenglibaihao, Fengshouhuang, Xu 61. Dl included 3 genotypes, viz., 460363, Meiguohong, Xushu 18. D2 included 3 genotypes, viz., No.9 Tainong, Banlihuang, Liaoshu 224. D3 included 6 genotypes, viz., 4600^1, 460097, Nanruishao, 46039, No.2 Sushu, Gaoxi 14. D4 included 2 genotypes, viz.,Zaengyinghong, No.l Anshu,. D5 included 1 genotypes, viz., NO.2 Yanshu. D4 included 1 genotypes, viz., Xiangshu.