State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093, People's Republic of China.
Planta. 2010 May;231(6):1301-9. doi: 10.1007/s00425-010-1134-9. Epub 2010 Mar 12.
Boron (B) is an essential micronutrient for plants, which when occurs in excess in the growth medium, becomes toxic to plants. Rapid inhibition of root elongation is one of the most distinct symptoms of B toxicity. Hydrogen sulfide (H(2)S) is emerging as a potential messenger molecule involved in modulation of physiological processes in plants. In the present study, we investigated the role of H(2)S in B toxicity in cucumber (Cucumis sativus) seedlings. Root elongation was significantly inhibited by exposure of cucumber seedlings to solutions containing 5 mM B. The inhibitory effect of B on root elongation was substantially alleviated by treatment with H(2)S donor sodium hydrosulfide (NaHS). There was an increase in the activity of pectin methylesterase (PME) and up-regulated expression of genes encoding PME (CsPME) and expansin (CsExp) on exposure to high B concentration. The increase in PME activity and up-regulation of expression of CsPME and CsExp induced by high B concentration were markedly reduced in the presence of H(2)S donor. There was a rapid increase in soluble B concentrations in roots on exposure to high concentration B solutions. Treatment with H(2)S donor led to a transient reduction in soluble B concentration in roots such that no differences in soluble B concentrations in roots in the absence and presence of NaHS were found after 8 h exposure to the high concentration B solutions. These findings suggest that increases in activities of PME and expansin may underlie the inhibition of root elongation by toxic B, and that H(2)S plays an ameliorative role in protection of plants from B toxicity by counteracting B-induced up-regulation of cell wall-associated proteins of PME and expansins.
硼（B）是植物必需的微量元素，当它在生长介质中过量存在时，会对植物产生毒性。根伸长的迅速抑制是 B 毒性最明显的症状之一。硫化氢（H(2)S）作为一种潜在的信使分子，参与植物生理过程的调节。在本研究中，我们研究了 H(2)S 在黄瓜（Cucumis sativus）幼苗 B 毒性中的作用。将黄瓜幼苗暴露在含有 5mM B 的溶液中，根伸长明显受到抑制。用 H(2)S 供体硫氢化钠（NaHS）处理可显著减轻 B 对根伸长的抑制作用。在高 B 浓度下，果胶甲酯酶（PME）的活性增加，编码 PME（CsPME）和扩张蛋白（CsExp）的基因表达上调。高 B 浓度诱导的 PME 活性增加和 CsPME 和 CsExp 表达上调在 H(2)S 供体存在下明显减少。在高浓度 B 溶液处理下，根系中可溶性 B 浓度迅速增加。H(2)S 供体处理导致根系中可溶性 B 浓度短暂降低，因此在 8 小时暴露于高浓度 B 溶液后，在没有和存在 NaHS 的情况下，根系中可溶性 B 浓度没有差异。这些发现表明，PME 和扩张蛋白活性的增加可能是毒性 B 抑制根伸长的基础，而 H(2)S 通过拮抗 B 诱导的细胞壁相关蛋白 PME 和扩张蛋白的上调，在保护植物免受 B 毒性方面发挥了缓解作用。
