Calcium mediates root K+/Na+ homeostasis in poplar species differing in salt tolerance
Calcium mediates root K+/Na+ homeostasis in poplar species differing in salt tolerance
复制标题
钙介导耐盐性不同的杨树根部钾/钠稳态
DOI：
10.1093/treephys/tpp048
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发表时间：
2009-09-01
期刊：
影响因子：
4
通讯作者：
Xu, Yue
中科院分区：
文献类型：
--
作者：
Sun, Jian;Dai, Songxiang;Xu, Yue
采用非侵入式离子选择性微电极技术，研究了耐盐杨树种、胡杨和盐敏小小叶杨（P.pyramalis + Salix matsudana）（Populus popalis 35-44，P.popalis）成熟根部和顶端区域的 K+、Na+ 和 H+ 通量分布，以及 Ca2+ 对离子通量的影响。与普通胡杨相比，胡杨根在暴露于盐冲击（SS，100 mM NaCl）和长期（LT）盐度（50 mM NaCl，3周）后表现出更大的保留K+的能力。两个物种中盐休克诱导的 K+ 外流明显受到 K+ 通道阻滞剂氯化四乙铵的限制，但被质膜 (PM) H+ -ATP 酶抑制剂原钒酸钠增强，表明 K+ 外流是由去极化激活 (DA) 通道介导的，例如去极化激活 (DA) 通道。例如，KORC（外向整流 K+ 通道）和 NSCC（非选择性阳离子通道）。在 LT 实验中，胡杨根比胡杨根更能有效地排除 Na+，这是由于 Na+/H+ 穿过 PM 的反向转运造成的。此外，药理学证据表明，盐化胡杨根中控制 K+/Na+ 稳态的能力更强，与更高的 H+ 泵活性相关，这为 Na+/H+ 交换提供了电化学 H+ 梯度，同时减少了 NaCl 诱导的 PM 去极化，从而减少了通过 NSCC 的 Na+ 流入和通过 DA-KORC 和 DA-NSCC 的 K+ 流出。 Ca2+ 的施用显着限制了盐诱导的 K+ 外流，但增强了表观 Na+ 外流，从而使这两个物种，特别是对盐敏感的杨树，能够在暴露于长期 NaCl 处理的根部中保持 K+/Na+ 稳态。
Using the non-invasively ion-selective microelectrode technique, flux profiles of K+, Na+ and H+ in mature roots and apical regions, and the effects of Ca2+ on ion fluxes were investigated in salt-tolerant poplar species, Populus euphratica Oliver and salt-sensitive Populus simonii x (P. pyramidalis + Salix matsudana) (Populus popularis 35-44, P. popularis). Compared to P. popularis, P. euphratica roots exhibited a greater capacity to retain K+ after exposure to a salt shock (SS, 100 mM NaCl) and a long-term (LT) salinity (50 mM NaCl, 3 weeks). Salt shock-induced K+ efflux in the two species was markedly restricted by K+ channel blocker, tetraethylammonium chloride, but enhanced by sodium orthovanadate, the inhibitor of plasma membrane (PM) H+ -ATPase, suggesting that the K+ efflux is mediated by depolarization-activated (DA) channels, e. g., KORCs (outward rectifying K+ channels) and NSCCs (nonselective cation channels). Populus euphratica roots were more effective to exclude Na+ than P. popularis in an LT experiment, resulting from the Na+/H+ antiport across the PM. Moreover, pharmacological evidence implies that the greater ability to control K+/Na+ homeostasis in salinized P. euphratica roots is associated with the higher H+ -pumping activity, which provides an electrochemical H+ gradient for Na+/H+ exchange and simultaneously decreases the NaCl-induced depolarization of PM, thus reducing Na+ influx via NSCCs and K+ efflux through DA-KORCs and DA-NSCCs. Ca2+ application markedly limited salt-induced K+ efflux but enhanced the apparent Na+ efflux, thus enabling the two species, especially the salt-sensitive poplar, to retain K+/Na+ homeostasis in roots exposed to prolonged NaCl treatment.