Recent Topics Posters
Cappa, Jennifer J. , Marcus, Matthew , Fakra, Sirine , Pilon-Smits, Elizabeth A.H. .
Differential selenium accumulation and allocation in three varieties of Stanleya pinnata (Brassicaceae) .
Stanleya pinnata (Brassicaceae) is able to accumulate up to 0.4% of its dry weight as selenium (Se). Within S. pinnata, three varieties have been proposed: integrifolia, pinnata and inyoensis. To study the Se accumulation properties of each variety, leaves, siliques and associated soil from each variety were collected from wild populations (3 populations, 3 individuals/population), and analyzed for Se concentration. The seeds were then grown on agar containing varying Se concentrations to test for Se accumulation under controlled conditions. The leaves and seeds were also analyzed for Se spatial distribution and chemical speciation using X-ray Absorption Spectroscopy at the Advanced Light Source. The field results showed substantial variation in Se accumulation within populations for all three varieties. Nevertheless, there was a gradation in accumulation as follows: var. pinnata > var. integrifolia > var. inyoensis. Stanleya pinnata var. pinnata appears to be the only true hyperaccumulator based on the criterion that it contained Se levels >0.1% of dry weight. Variety pinnata had significantly higher tissue Se levels than the other two varieties. In the lab study, var. integrifolia accumulated more SeĀ than var. inyoensis. There were also differences between the varieties with respect to spatial distribution of Se in leaves and seeds. In var. pinnata, Se distribution was diffuse throughout the leaf, whereas var. integrifolia contained Se mainly in the leaf margins and var. inyoensis had the Se mainly in the vascular tissue. In seeds, var. integrifolia and pinnata accumulated Se mainly in the embryo, while in var. inyoensis Se was found in the seed coat. These studies provide evidence for differential Se allocation and accumulation between the varieties of S. pinnata. Currently a phylogenetic study is underway on Stanleya and in conjuction with the physiology may shed light on the evolution of Se hyperaccumulation.
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1 - Colorado State University, Department of Biology, Fort Collins, Colorado, 80523-1878, U.S.A.
2 - Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, U.S.A.
3 - Colorado State University, Department of Biology, Fort Collins, CO, 80523, U.S.A.
Presentation Type: Recent Topics Poster
Location: Event Tent/Cliff Lodge
Date: Monday, July 27th, 2009
Time: 5:30 PM