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Selenium accumulation in the floral tissues of two Brassicaceae species and its impact on floral traits and plant performance
- Hladun, Kristen R., Parker, David R., Trumble, John T.
- Environmental and experimental botany 2011 v.74 pp. 90-97
- Brassica juncea, Stanleya, agricultural runoff, corolla, environmental factors, greenhouses, leaves, nectar, nectar plants, plant tissues, pods, pollen, pollinators, polluted soils, reproductive traits, risk, sand, seeds, selenium, shale, soil water
- Selenium (Se) is a metalloid that can occur naturally in soils from the Cretaceous shale deposits of a prehistoric inland sea in the western United States. Agricultural irrigation and runoff solubilizes Se from these shales, causing buildups of toxic levels of selenate (SeOâ Â²â») in water and soil. Our main objective was to investigate the accumulation of Se in two Brassicaceae species chosen for their potential as phytoremediators of Se contaminated soils. We tested the hypothesis that Se will accumulate in the pollen and nectar of two plant species and negatively affect floral traits and plant reproduction. Certain species of Brassicaceae can accumulate high concentrations of Se in their leaf tissues. In this study Se accumulation in plant tissues was investigated under greenhouse conditions. Se accumulator (Brassica juncea) and Se hyperaccumulator (Stanleya pinnata) plants were irrigated in sand culture with 0Î¼M selenate (control), 8Î¼M selenate, and 13Î¼M selenate. Nectar and pollen in S. pinnata contained up to 150Î¼gSemLâ»Â¹ wet weight and 12900Î¼gSegâ»Â¹dry weight when irrigated with 8Î¼M selenate. Se levels in nectar (110Î¼gSemLâ»Â¹wet weight) and pollen (1700Î¼gSegâ»Â¹dry weight) were not as high in B. juncea. Floral display width, petal area and seed pod length were significantly reduced in the 13Î¼M selenate Se treatment in B. juncea. S. pinnata floral traits and seeds were unaffected by the Se treatments. This study provides crucial information about where some of the highest concentrations of Se are found in two phytoremediators, and may shed light on the potential risks pollinators may face when foraging upon these accumulating plants. In the field, duration of the plant's exposure, Se soil and water concentrations as well as other environmental factors may also play important roles in determining how much Se is accumulated into the leaf and floral tissues. Our greenhouse study shed light on two speciesâ ability to accumulate Se, as well as determined the specific plant tissues where Se concentrations are highest.