Assessment of Genetic Diversity of Sweetpotato (Ipomoea batatas L.) In Puerto Rico

Sweetpotato (SP) is the seventh most important food crop after maize, wheat, rice, barley, potato and cassava. Due to its many agricultural advantages, such as adaptability to different environmental conditions and its nutritional value, research endeavors in sweetpotato are increasing. SP in Puerto Rico (PR) is poorly understood and there is a need to assess its diversity, especially since most are cultivated and maintained by farmers. A total of 155 samples were analyzed with 23 SSR markers using a fluorescent PCR technique. As a comparison we included known SP varieties from PR and the USDA SP germplasm collection. The analysis revealed a total of 205 alleles, with an average of 8.9 alleles.Overall average H_o(0.637) was high across populations while measurements of H_t (0.731) revealed a large genetic diversity throughout the populations.Two main clusters were depicted using UPGMA clustering method. Cluster I contained 19 unknown accessions from across the island while cluster II had the majority of unknown samples as well as the known accessions from PR and USDA. Cluster II was subdivided into 4 smaller sub-clusters. We conclude that there is a high level of genetic diversity across PR which can be related to genetic makeup of SP, the ability to be vegetatively propagated, human intervention and the outcrossing nature of SP. High levels of genetic diversity found in PR and the history of domestication and dispersal of SP makes it an extremely valuable resource that needs to be protected and further studied.