Department of Plant Biology, University of Szeged, Közép alley 52, 6726, Szeged, Hungary.
Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm square 7, 6720, Szeged, Hungary.
Plant Physiol Biochem. 2023 Sep;202:107976. doi: 10.1016/j.plaphy.2023.107976. Epub 2023 Aug 18.
Selenium (Se) hyperaccumulators are capable of uptake and tolerate high Se dosages. Excess Se-induced oxidative responses were compared in Astragalus bisulcatus and Astragalus cicer. Plants were grown on media supplemented with 0, 25 or 75 μM selenate for 14 days. Both A. bisulcatus and A. cicer accumulated >2000 μg/g dry weight Se to the shoot but the translocation factors of A. cicer were below 1 suggesting its non hyperaccumulator nature. A. cicer showed Se sensitivity indicated by reduced seedling fresh weight, root growth and root apical meristem viability, altered element homeostasis in the presence of Se. In Se-exposed A. bisulcatus, less toxic organic Se forms (mainly MetSeCys, γ-Glu-MetSeCys, and a selenosugar) dominated, while these were absent from A. cicer suggesting that the majority of the accumulated Se may be present as inorganic forms. The glutathione-dependent processes were more affected, while ascorbate levels were not notably influenced by Se in either species. Exogenous Se triggered more intense accumulation of malondialdehyde in the sensitive A. cicer compared with the tolerant A. bisulcatus. The extent of protein carbonylation in the roots of the 75 μM Se-exposed A. cicer exceeded that of A. bisulcatus indicating a correlation between selenate sensitivity and the degree of protein carbonylation. Overall, our results reveal connection between oxidative processes and Se sensitivity/tolerance/hyperaccumulation and contribute to the understanding of the molecular responses to excess Se.
硒（Se）超富集植物能够吸收并耐受高剂量的 Se。本研究比较了黄芪（Astragalus bisulcatus）和野豌豆（Astragalus cicer）在过量 Se 诱导的氧化应激反应。植物在补充 0、25 或 75 μM 硒酸盐的培养基上生长 14 天。两种黄芪都将超过 2000μg/g 干重的 Se 积累到地上部分，但野豌豆的转运因子低于 1，表明其非超富集特性。野豌豆表现出对 Se 的敏感性，表现在幼苗鲜重、根生长和根尖分生组织活力降低，以及在 Se 存在下元素稳态的改变。在暴露于 Se 的黄芪中，主要存在毒性较小的有机 Se 形式（主要是 MetSeCys、γ-Glu-MetSeCys 和一种硒糖），而野豌豆中则不存在这些形式，这表明大部分积累的 Se 可能以无机形式存在。谷胱甘肽依赖的过程受到的影响更大，而在两种物种中，As 水平都没有明显受到 Se 的影响。与耐受的黄芪相比，外源 Se 触发了更敏感的野豌豆中丙二醛的更强烈积累。在暴露于 75 μM Se 的野豌豆根中，蛋白质羰基化的程度超过了黄芪，表明硒酸盐敏感性与蛋白质羰基化程度之间存在相关性。总的来说，我们的结果揭示了氧化过程与 Se 敏感性/耐受性/超积累之间的联系，有助于理解过量 Se 下的分子响应。
