DISSERTATION RESEARCH: The evolution of selenium hyperaccumulation in Stanleya (Brassicaceae)

Colorado State University, Fort Collins CO

Investigators

Abstract

Selenium is atomically similar to sulfur and because of this relationship it can replace sulfur in proteins. Accidental incorporation of selenium can cause disease and even death in humans, livestock and wildlife. Yet selenium is also an essential micronutrient for many animals, prokaryotes and algae, though there is no known function of selenium in land plants. There are four plant genera with species recognized as selenium hyperaccumulators (accumulating >0.1% dry weight selenium), including Stanleya (prince's plume; Brassicaceae) in the western United States. Stanleya includes seven species, one of which (Stanleya pinnata) is a known selenium hyperaccumulator. The goal of this project is to infer the process of diversification of selenium accumulation, tolerance, localization and chemical form in the context of intraspecific relationships within Stanleya to better understand which DNA changes caused these physiological changes. By understanding which DNA changes gave rise to selenium accumulation and tolerance we can improve crops for both phytoremediation (environmental clean-up using plants) and biofortification. Selenium deficiency is estimated to cause $545 million in losses to livestock producers every year. Stanleya pinnata metabolizes selenium into a healthy anti-carcinogenic form, and understanding this physiological pathway may lead to improved crops for both humans and livestock.