Cappa , Jennifer JoCarole , Yetter, Crystal , Fakra, Sirine , Marcus, Matthew , Simmons, Mark , Pilon-Smits, Elizabeth .
Characterization of selenium uptake and metabolism in Stanleya (Brassicaceae).
Selenium naturally occurs in soils around the globe with extreme variation in its concentration and distribution. Some soils have high concentrations of Se, particularly the western United States, due to the presence of seleniferous Cretaceous shale and chalk sediments. Owing to the similarity of Se to sulfur, most plants readily take up selenate from the environment and assimilate it into organic forms. A few plant genera even accumulate Se to levels typically 100-fold higher than surrounding vegetation on seleniferous soils (0.1-1% of dry weight); these species are called Se hyperaccumulators. Stanleya pinnata var. pinnata is a Se hyperaccumulator and occurs in most western states, while most of the other six species in Stanleya have narrow ranges and are endemic to a specific mountain range or desert. Stanleya pinnata var. pinnata incorporates Se into the non-protein amino acid methyl-selenocysteine (Me-SeCys), thereby preventing Se incorporation into proteins, and its associated toxicity. Six of the seven species of Stanleya where collected in the field. The leaves, siliques and soil from each individual were analyzed for in situ Se concentrations. The seeds were germinated and seedlings were tested for Se accumulation and tolerance in hydroponics. Seedlings were also grown in MS agar for analysis at the Advanced Light Source in Berkeley, CA for Se allocation and chemical speciation. Furthermore, four nuclear genes have been amplified in three individuals from differing populations for each species for use in phylogenetic inference. We have evidence of differential metabolism of Se within the genus Stanleya based on accumulation, tolerance, chemical speciation and Se sequestration. By combining these data in a phylogenetic context we can formulate hypotheses about the evolution of Se hyperaccumulation in Stanleya.
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1 - Colorado State University, Biology, Fort Collins, CO, 80523, USA
2 - Eastern University, St. Davids, PA, 19087, USA
3 - Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
4 - Colorado State University, Department Of Biology, FORT COLLINS, CO, 80523-1878, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Westminster Room/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 11:20 AM