Establishment of Molecular Linkage Maps Using SRAP Markers in Sweet Potato

Sweet potato [Ipomoea batatas(L.) Lam.] is an important vegetative reproduction crop.Despite its worldwide importance,molecular biology researches in sweet potato have lagged behind other crops due to its characteristics including polyploidy,outcrossing behavior,and high heterozygosity.As a result,it is difficult to make a breakthrough for the improvement of sweet potato using conventional methods.In this study,sequence-related amplified polymorphism(SRAP) markers were applied to establish molecular genetic linkage maps with F1 population consisting of 240 individuals derived from a cross of sweet potato cv.Luoxushu 8(high starch content cultivar)×cv.Zhengshu 20(low starch content cultivar).A total of 770 and 523 SRAP markers were generated,respectively,in Luoxushu 8 and Zhengshu 20.Using the software of JoinMap 3.0 and the 'double pseudo testcross strategy',a molecular linkage map containing 81 linkage groups was established with 473 SRAP markers in Luoxushu 8,and the map covered 5 802.46 cM with an average marker interval of 10.16 cM.In Zhengshu 20,the molecular linkage map containing 66 linkage groups was constructed using 328 SRAP markers,and the map covered 3 967.90 cM with an average marker interval of 12.02 cM.These results will provide a powerful tool to facilitate the introgression of desired traits into cultivars,gene localization,and map-based cloning techniques,and greatly increase breeding efficiency through marker-assisted selection(MAS) techniques.