The AtNHX1 exchanger mediates potassium compartmentation in vacuoles of transgenic tomato
The AtNHX1 exchanger mediates potassium compartmentation in vacuoles of transgenic tomato
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DOI：
10.1111/j.1365-313x.2009.04073.x
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发表时间：
2010-02-01
期刊：
影响因子：
7.2
通讯作者：
Pardo, Jose M.
中科院分区：
文献类型：
--
作者：
Leidi, Eduardo O.;Barragan, Veronica;Pardo, Jose M.
据报道，液泡膜中的NHX型反向转运蛋白可提高多种植物的耐盐性，并被认为介导Na+在液泡中的区室化。然而，迄今为止表征的所有同种型催化Na+/H+和K+/H+交换。在这里，我们表明，AtNHX 1有一个关键的参与亚细胞分配的K+，这反过来又影响植物K+营养和Na+的耐受性。过表达AtNHX 1的转基因番茄植株在所有生长条件下都具有较大的K+液泡库，但在盐胁迫下没有观察到Na+积累的一致增强。过表达AtNHX 1的植物具有更大的能力来保留细胞内的K+和耐受盐激。在K+限制条件下，更大的K+ compartmentation在液泡中发生在细胞质K+池，这是在转基因植物较低的费用。这导致高亲和力K+吸收系统的早期激活，增强了根系对K+的吸收，并增加了转化植株组织和木质部汁液中的K+含量。我们的研究结果强烈表明，NHX蛋白是可能的候选人的H+连接的K+运输，被认为是促进积极的K+在液泡膜的吸收，和分配的K+之间的液泡和胞质溶胶。
NHX-type antiporters in the tonoplast have been reported to increase the salt tolerance of various plants species, and are thought to mediate the compartmentation of Na+ in vacuoles. However, all isoforms characterized so far catalyze both Na+/H+ and K+/H+ exchange. Here, we show that AtNHX1 has a critical involvement in the subcellular partitioning of K+, which in turn affects plant K+ nutrition and Na+ tolerance. Transgenic tomato plants overexpressing AtNHX1 had larger K+ vacuolar pools in all growth conditions tested, but no consistent enhancement of Na+ accumulation was observed under salt stress. Plants overexpressing AtNHX1 have a greater capacity to retain intracellular K+ and to withstand salt-shock. Under K+-limiting conditions, greater K+ compartmentation in the vacuole occurred at the expense of the cytosolic K+ pool, which was lower in transgenic plants. This caused the early activation of the high-affinity K+ uptake system, enhanced K+ uptake by roots, and increased the K+ content in plant tissues and the xylem sap of transformed plants. Our results strongly suggest that NHX proteins are likely candidates for the H+-linked K+ transport that is thought to facilitate active K+ uptake at the tonoplast, and the partitioning of K+ between vacuole and cytosol.