ZxAKT1 is essential for K+ uptake and K+/Na+ homeostasis in the succulent xerophyte Zygophyllum xanthoxylum
ZxAKT1 is essential for K+ uptake and K+/Na+ homeostasis in the succulent xerophyte Zygophyllum xanthoxylum
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ZxAKT1 对于肉质旱生植物 Zygophyllum xanthoxylum 的 K 吸收和 K/Na 稳态至关重要
DOI：
10.1111/tpj.13465
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发表时间：
2017-04-01
期刊：
影响因子：
7.2
通讯作者：
Wang, Suo-Min
中科院分区：
文献类型：
--
作者：
Ma, Qing;Hu, Jing;Wang, Suo-Min
内向整流型K+通道AKT1是植物根部获得K+的重要途径。在糖类植物中，盐胁迫下Na+的过度积累伴随着K+的缺乏。然而，在对恶劣环境具有良好适应能力的肉质旱生植物Zygophyllum xanthox中，尽管在盐分和干旱条件下Na+水平增加，但K+浓度保持在相对恒定的水平。本研究探讨了ZxAKT1在维持花椒K+、Na+动态平衡中的作用。ZxAKT1的表达挽救了酵母菌株CY162的K+吸收缺陷表型，抑制了酵母菌株G19的盐敏感表型，补充了拟南芥AKT1突变体的低K+敏感性表型，表明ZxAKT1具有内向整流型K+通道的功能。ZxAKT1主要在根中表达，并在高浓度的KCl或NaC l诱导下表达。利用RNA干扰技术，我们发现与野生型花椒相比，ZxAKT1沉默的植株表现出生长发育迟缓。进一步的实验表明，与野生型花椒相比，ZxAKT1沉默的植株对K+和Na+的净吸收显著下降，导致K+和Na+浓度降低。与野生型相比，与K+/Na+动态平衡相关的几个转运蛋白/通道的编码基因，包括ZxSKOR、ZxNHX、ZxSOS1和ZxHKT1；1，在ZxAKT1沉默系的不同组织中表达水平降低。这些结果表明，ZxAKT1不仅在花椒对K+的吸收中起关键作用，而且还在调节花椒对Na+的吸收和运输系统中发挥作用，从而影响其正常生长。
The inward-rectifying K+ channel AKT1 constitutes an important pathway for K+ acquisition in plant roots. In glycophytes, excessive accumulation of Na+ is accompanied by K+ deficiency under salt stress. However, in the succulent xerophyte Zygophyllum xanthoxylum, which exhibits excellent adaptability to adverse environments, K+ concentration remains at a relatively constant level despite increased levels of Na+ under salinity and drought conditions. In this study, the contribution of ZxAKT1 to maintaining K+ and Na+ homeostasis in Z. xanthoxylum was investigated. Expression of ZxAKT1 rescued the K+ -uptake-defective phenotype of yeast strain CY162, suppressed the salt-sensitive phenotype of yeast strain G19, and complemented the low-K+ -sensitive phenotype of Arabidopsis akt1 mutant, indicating that ZxAKT1 functions as an inward-rectifying K+ channel. ZxAKT1 was predominantly expressed in roots, and was induced under high concentrations of either KCl or NaCl. By using RNA interference technique, we found that ZxAKT1-silenced plants exhibited stunted growth compared to wild-type Z. xanthoxylum. Further experiments showed that ZxAKT1-silenced plants exhibited a significant decline in net uptake of K+ and Na+ , resulting in decreased concentrations of K+ and Na+ , as compared to wild-type Z. xanthoxylum grown under 50 mm NaCl. Compared with wild-type, the expression levels of genes encoding several transporters/channels related to K+ /Na+ homeostasis, including ZxSKOR, ZxNHX, ZxSOS1 and ZxHKT1;1, were reduced in various tissues of a ZxAKT1-silenced line. These findings suggest that ZxAKT1 not only plays a crucial role in K+ uptake but also functions in modulating Na+ uptake and transport systems in Z. xanthoxylum, thereby affecting its normal growth.