DISSERTATION RESEARCH: Evolution of polyploidy and storage roots in sweet potato and its wild relatives

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Sweet potato, with its carbohydrate- and vitamin-rich storage roots, is a vital source of nutrition for people in many countries. Current efforts to improve crop yield in sweet potato are focused on a small number of breeding lines. Wild relatives of crop species can also be an important source of genetic material for crop improvement, but the evolutionary relationships between sweet potato and its wild relatives are currently unknown. This project will use genomic data to reconstruct evolutionary relationships between sweet potato and its wild relatives, and shed light on the genetic changes that have contributed to the evolution of the carbohydrate- and vitamin-rich storage root in cultivated sweet potato. Root characteristics and genetic variation are poorly known for wild relatives of sweet potato and this project will provide a greatly improved understanding of the potential of wild relatives for sweet potato breeding programs. The project will train one graduate student and several undergraduates in laboratory techniques. Results from the research will be integrated within new teaching materials for middle school, high school and undergraduate students that emphasize the domestication process and importance of diversity in crop breeding programs.This research will characterize the timing of whole genome duplication events within sweet potato (Ipomoea batatas) and closely related species, and test whether these events are linked to the evolution of storage roots in the group. Numerous studies have implicated polyploidy as a major driving factor in the evolution of complex phenotypes; however, few studies have linked whole genome duplication events with the evolution of novel root traits. This study will apply modern phylogenomic methods to estimate relationships within the Ipomoea batatas complex and reconstruct the history of polyploidization and storage root development in the group. Genetic markers developed through gene capture and Restriction site Associated DNA Sequencing (RADSeq) technologies through this research will be useful for germplasm stock centers characterizing and preserving diversity within sweet potato and across the Ipomoea batatas complex. These findings will advance sweet potato breeding efforts, including recent work to develop productive and robust cultivars for Africa.