Abstract
Ipomoea batatas (sweet potato) is one of the most important corps in the world. Although cultivated sweet potatoes have been domesticated for more than 5,000 years, their domestication mechanisms remain unclear. To investigate whether 89 different cultivated sweet potatoes have experienced selected stresses during domestication, simple sequence repeats (SSRs) derived from expressed sequence tags (ESTs) were genotyped. Genetic structural analyses in PCoA indicated two separated groups, i.e. wild species and sweet potatoes, consisting with the result of other analyses. Analyses reveal that the polymorphism of sampled loci is about 97.4%. In addition, gene diversity appears much higher in cultivated sweet potatoes than in wild species. We detected five selected loci by different analyses. Our results suggest that domesticated species have experienced selected stresses. Selected loci are related to primary metabolism such as gene expression and photosynthesis. Because selected genes of primary metabolites have been found in cereal crops, combining with our findings in the sweet potatoes, a non-cereal crop, we propose that selection of primary metabolism genes might be common in domestication of crops.
