RESEARCH-PGR: Multiple origins of tuber formation: Evolution of a unique storage organ

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As with the majority of animals, plants reproduce sexually and are subsequently dispersed through fruits and seeds. However, numerous plant species are also able to reproduce asexually via modified below-ground storage organs as seen in potatoes, onions, and daffodils. These below-ground organs provide a means for survival during the winter and/or prolonged periods of environmental stress as well as a means to bypass sexual reproduction. One type of storage organ is that of a tuber. Tuber crops provide significant calories and nutrition worldwide and are an especially important component of food security in developing countries as exemplified by potatoes and yams. The trait of tuber production has evolved multiple times throughout the history of flowering plants. Based on studies in potato, the signals to make tubers are related to genes involved in flowering including genes that sense daylength and genes that control the 24-hour daily rhythm of all organisms, suggesting that the origin of tubers is an ancient trait. This project will employ state-of-the art technologies in genome biology to provide new insights into the mechanisms of tuber development and evolution and help to train the next generation of scientists in computational methods. In addition, the project will demonstrate the importance of tuber crops in food security through educational activities with the public.Understanding the origin and evolution of novel complex traits is a fundamental goal in biology. Tubers, below-ground storage organs derived from stems, provide significant calories and nutrition worldwide and are an especially important component of food security in developing countries as exemplified by potato, yam, oca, kaffir potato, ulluco and mashua. The trait of tuber production has evolved multiple times throughout the history of angiosperms across taxa separated by ~130 million years of evolution. Although it has long been hypothesized, only within the last decade have studies demonstrated that many novel traits are encoded by pre-existing genes and regulatory networks. This project will employ an integrated comparative genomics approach in which multiple species-pairs that have evolved the ability to produce alternative reproductive structures (i.e., tuber) will enable identification of "core" genes, sets of interacting pathways, and encoded processes necessary for tuber production. Models for tuberization will be validated using functional genomics approaches and experimental data used to refine models of tuber development. This project will train students in computational plant biology and data science to address gaps in the scientific workforce. In addition, this project will mentor under-represented groups in science research through participation in the Michigan State University National Migrant Scholars Internship Initiative and engage the lay public in the importance of tuber crops in food security through activities with the Michigan State University 4-H Children?s Garden.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.