Construction linkage maps and identification of quantitative trait loci associated with important agronomic traits in purple-fleshed sweetpotato

: Ideal agronomic traits are the important objectives in sweetpotato breeding, but the breeding methods are still lacking. We constructed linkage maps using a mapping population of 274 individuals derived from a cross between the female parent Xuzishu 8 (a purple-fleshed cultivar with many branches, medium vine, and high yield) and the male parent Meiguohong (a white-fleshed cultivar with few branches, long vine, and medium yield) by simple sequence repeats (SSR) markers in this study. The female parent map contained 24 linkage groups, and covered 1325.8 cM with an average marker interval of 9.2 cM. The male parent map contained 21 linkage groups, and covered 1088.6 cM with an average marker interval of 8.2 cM. The maps could in-crease the density of existing genetic maps. Using the composite interval mapping, we analyzed five important agronomic traits, including branch number, vine diameter, longest vine length, petiole length, and internode length in sweetpotato, thus identified one QTL related to branch number explaining the phenotypic variance of 53.2%, one QTL related to internode diameter explaining the phenotypic variance of 16.7%, two QTLs related to longest vine length explaining the phenotypic variance of 9.5% and 13.7%, two QTLs related to petiole length explaining the phenotypic variance of 8.8% and 11.3%, and five QTLs related to inter-2148 node length explaining the phenotypic variance of 9.6%–28.1%. The QTLs can be used to develop molecular markers and assist the screening of plants with ideal agronomic traits at early seedling stage, thus improved the efficiency of field selection.