The Use of RAPD,ISSR and AFLP Markers for Analyzing Genetic Relationships among Sweetpotato Cultivars with Known Origin

Sweetpotato,Ipomoea batatas(L.) Lam.,is an important crop as food,feed and industrial materials grown worldwide.Because of its many biological complexities such as natural heterozygote and cross-incompatibility,the analysis of the genetic relationships among cultivars is of interest not only for germplasm conservation but also for breeding purposes.Molecular techniques have been used broadly for germplasm characterization,variety identification,phylogenetic study and diversity analysis.There has been no report on analyzing genetic relationships among sweetpotato cultivars with known origin using molecular markers.In the present study,genetic relationships among seven sweetpotato cultivars with known origin were analysed using RAPD,ISSR and AFLP markers(Fig.1).Twenty-four RAPD primers,14 ISSR primers and 9 AFLP primer pairs generated 173,174 and 168 polymorphic bands,respectively(Fig.2,Table 1).For detecting the genetic differences among sweetpotato cultivars,the correlations among RAPD,ISSR and AFLP markers were significant with the highest correlation coefficient between RAPD and ISSR markers(0.9328).The ISSR-based genetic distances among the 7 sweetpotato cultivars,ranging from 0.1286 to 1.0932 with an average of 0.4883,were higher than those calculated with the other two markers.The dendrograms based on RAPD,ISSR and AFLP markers could separately detect genetic relationships of the 7 sweetpotato cultivars and the ISSR-based dendrogram was the best in agreement with their known origin,suggesting that ISSR is the powerful marker for analyzing genetic relationships among sweetpotato cultivars(Fig.3).