Stimulus-induced downregulation of root water transport involves reactive oxygen species-activated cell signalling and plasma membrane intrinsic protein internalization
Stimulus-induced downregulation of root water transport involves reactive oxygen species-activated cell signalling and plasma membrane intrinsic protein internalization
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DOI：
10.1111/j.1365-313x.2008.03594.x
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发表时间：
2008-10-01
期刊：
影响因子：
7.2
通讯作者：
Maurel, Christophe
中科院分区：
文献类型：
--
作者：
Boursiac, Yann;Boudet, Julie;Maurel, Christophe
植物根部的吸水能力（即水力传导率 Lp(r)）在很大程度上由质膜内在蛋白 (PIP) 亚家族的水通道蛋白决定。在目前的工作中，我们研究了两种刺激物：水杨酸（SA）和盐，因为它们能够诱导拟南芥植物根部活性氧（ROS）的积累并同时抑制 Lp（r）。 SA对Lp(r)的抑制通过外源过氧化氢酶阻止过氧化氢(H(2)O(2))的积累而部分抵消。此外，外源性 H(2)O(2) 能够在 15 分钟内将 Lp(r) 降低高达 90%。基于H(2)O(2)对非洲爪蟾卵母细胞中单个水通道蛋白活性缺乏影响，以及对H(2)O(2)对Lp(r)作用的药理学剖析，我们提出ROS并不通过直接氧化机制来控制拟南芥根水通道蛋白，而是通过细胞信号传导机制发挥作用。 PIP-GFP 融合体转基因根中的表达和免疫金标记表明，外部 H(2)O(2) 在 15 分钟内增强了 PIP 在初步鉴定为囊泡和小液泡的细胞内结构中的积累。根部暴露于 SA 或盐也会诱导 PIP-GFP 融合蛋白在细胞内积累，并且这些效应可通过与外源过氧化氢酶共处理来完全抵消。总之，目前的工作将 SA 确定为水通道蛋白的新型调节剂，并描绘了拟南芥根中的 ROS 依赖性信号通路。几种非生物和生物胁迫相关的刺激可能共享这条路径，其中涉及 H(2)O(2) 诱导的 PIP 内化，以下调根部水分运输。
The water uptake capacity of plant roots (i.e. their hydraulic conductivity, Lp(r)) is determined in large part by aquaporins of the plasma membrane intrinsic protein (PIP) subfamily. In the present work, we investigated two stimuli, salicylic acid (SA) and salt, because of their ability to induce an accumulation of reactive oxygen species (ROS) and an inhibition of Lp(r) concomitantly in the roots of Arabidopsis plants. The inhibition of Lp(r) by SA was partially counteracted by preventing the accumulation of hydrogen peroxide (H(2)O(2)) with exogenous catalase. In addition, exogenous H(2)O(2) was able to reduce Lp(r) by up to 90% in < 15 min. Based on the lack of effects of H(2)O(2) on the activity of individual aquaporins in Xenopus oocytes, and on a pharmacological dissection of the action of H(2)O(2) on Lp(r), we propose that ROS do not gate Arabidopsis root aquaporins through a direct oxidative mechanism, but rather act through cell signalling mechanisms. Expression in transgenic roots of PIP-GFP fusions and immunogold labelling indicated that external H(2)O(2) enhanced, in < 15 min, the accumulation of PIPs in intracellular structures tentatively identified as vesicles and small vacuoles. Exposure of roots to SA or salt also induced an intracellular accumulation of the PIP-GFP fusion proteins, and these effects were fully counteracted by co-treatment with exogenous catalase. In conclusion, the present work identifies SA as a novel regulator of aquaporins, and delineates an ROS-dependent signalling pathway in the roots of Arabidopsis. Several abiotic and biotic stress-related stimuli potentially share this path, which involves an H(2)O(2)-induced internalization of PIPs, to downregulate root water transport.