Genetic diversity and population structure of sweet potato landraces based on phenotypic traits, carotenoid content, and SSR molecular markers

Germplasm resources are an important basis for genetic breeding, and the study of genetic diversity is beneficial to the discovery and improvement of germplasm resources. In this study, 132 local germplasm of sweet potato were used as test materials, and 20 phenotypic traits were analyzed for genetic diversity using distribution frequency, coefficient of variation, and Shannon's diversity index; carotenoid contents in sweet potato tubers were measured by HPLC, and their genetic diversity was analyzed using the coefficient of variation, mean, and standard deviation. Meanwhile, the genetic diversity, as well as population structure, were analyzed based on 10 pairs of SSR molecular markers using Nei's genetic diversity index and Shannon's diversity index. The results showed that the 132 sweet potato landraces had high genetic diversity based on phenotypic traits, SSR molecular markers, and carotenoid content, respectively; based on population structure analysis, the 132 sweet potato landraces could be divided into five subgroups. Analysis of molecular variation (AMOVA) showed that 84% of the variation existed within populations and 16% between populations. This study provides a basis for the selection of parental material for the genetic breeding improvement of sweet potato and for the mining of superior genes.