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

红薯有着富含碳水化合物和维生素的根茎，对许多国家的人们来说是重要的营养来源。目前提高甘薯作物产量的努力集中在少数育种系上。作物物种的野生近缘也可能是作物改良的重要遗传物质来源，但甘薯与其野生近缘之间的进化关系目前尚不清楚。该项目将使用基因组数据重建甘薯及其野生近缘之间的进化关系，并阐明导致栽培甘薯富含碳水化合物和维生素的贮藏根进化的遗传变化。甘薯野生近缘种的根系特征和遗传变异知之甚少，该项目将极大地提高对野生近缘种在甘薯育种中的潜力的了解。该项目将对一名研究生和几名本科生进行实验室技术方面的培训。这项研究的结果将被整合到初中、高中和本科生的新教材中，强调驯化过程和作物育种计划中多样性的重要性。这项研究将表征甘薯(Ipomoea Batatas)和密切相关物种中全基因组复制事件的时间，并测试这些事件是否与群体中贮藏根的进化有关。许多研究表明，多倍体是复杂表型进化的主要驱动因素；然而，很少有研究将全基因组复制事件与新的根性状的进化联系起来。这项研究将应用现代系统基因组学方法来评估甘薯复合体内的亲缘关系，并重建该群体的多倍化和贮藏根发育的历史。通过本研究开发的基因捕获和限制位点相关DNA测序(RADSeq)技术开发的遗传标记将有助于甘薯种质资源中心鉴定和保存甘薯和甘薯复合体的多样性。这些发现将推动甘薯育种工作，包括最近为非洲开发高产和健壮的品种的工作。

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.