Ionic and osmotic effects of NaCl-induced inactivation of photosystems I and II in Synechococcus sp.
Ionic and osmotic effects of NaCl-induced inactivation of photosystems I and II in Synechococcus sp.
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DOI：
10.1104/pp.123.3.1047
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发表时间：
2000-07-01
期刊：
影响因子：
7.4
通讯作者：
Murata, N
中科院分区：
文献类型：
--
作者：
Allakhverdiev, SI;Sakamoto, A;Murata, N
我们在这里报告，渗透效应和离子效应都参与了氯化钠诱导的光合机构在蓝藻聚球藻7942的失活。在0.5 M NaCl中孵育的蓝藻细胞诱导的光系统（PS）II的放氧活性和PSI的电子传递活性的快速和可逆的下降和随后的缓慢和不可逆的损失。Na+通道阻滞剂保护PSII和PSI对缓慢，但不是快速，失活。快速下降类似于1.0 M山梨醇的作用。钠离子通道阻滞剂和水通道阻滞剂的存在下保护PSI和PSII对短期和长期的NaCl的影响。盐胁迫也降低了细胞质体积，Na+通道阻滞剂增强了这种效果。我们的观察表明，NaCl具有渗透和离子效应。渗透作用减少了细胞质中的水量，迅速增加了细胞内盐的浓度。离子效应是由Na+离子通过钾/Na+通道流入引起的，这也增加了细胞质中盐的浓度，并不可逆地灭活PSI和PSII。
We report here that osmotic effects and ionic effects are both involved in the NaCl-induced inactivation of the photosynthetic machinery in the cyanobacterium Synechococcus sp. PCC 7942. Incubation of the cyanobacterial cells in 0.5 M NaCl induced a rapid and reversible decline and subsequent slow and irreversible loss of the oxygen-evolving activity of photosystem (PS) II and the electron transport activity of PSI. An Na+-channel blocker protected both PSII and PSI against the slow, but not the rapid, inactivation. The rapid decline resembled the effect of 1.0 M sorbitol. The presence of both an Na+-channel blocker and a water-channel blocker protected PSI and PSII against the short- and long-term effects of NaCl. Salt stress also decreased cytoplasmic volume and this effect was enhanced by the Na+-channel blocker. Our observations suggested that NaCl had both osmotic and ionic effects. The osmotic effect decreased the amount of water in the cytosol, rapidly increasing the intracellular concentration of salts. The ionic effect was caused by an influx of Na+ ions through potassium/Na+ channels that also increased concentrations of salts in the cytosol and irreversibly inactivated PSI and PSII.