Department of Biology, Environmental Research Unit, College of Haql, University of Tabuk, Tabuk, 71491, Saudi Arabia.
Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, 2455, Saudi Arabia.
Plant Physiol Biochem. 2021 Feb;159:211-225. doi: 10.1016/j.plaphy.2020.11.055. Epub 2020 Dec 8.
Present investigation reports the role of calcium (Ca) and hydrogen sulfide (HS) crosstalk associated with Vigna radiata seedlings subjected to K deficient conditions under short-term (24 h) and long-term (72 h) NaCl stress. Perusal of the data reveals that under short-term NaCl stress an initial decline in K level led to the elevation in Ca and HS levels along with improvement in antioxidant system and reduction in reactive oxygen species (ROS) production. Under long-term NaCl stress a further decline in K content was deleterious that led to a lower K/Na ratio. This was followed by reduction in antioxidant system along with excessive accumulation of ROS and methylglyoxal content, and increased membrane damage. However, supplementation of the seedling roots with Ca enhanced biosynthesis of HS through enhancing cysteine pool. The present findings suggest that synergistic action of Ca and HS induced the activity of H-ATPase that created H gradient which in turn induced Na/H antiport system that accelerated K influx and Na efflux. All of these together contributed to a higher K/Na ratio, activation of antioxidative defense system, and maintenance of redox homeostasis and membrane integrity in Ca-supplemented stressed seedlings. Role of Ca and HS in the regulation of Na/H antiport system was validated by the use of sodium orthovanadate (plasma membrane H-ATPase inhibitor), tetraethylammonium chloride (K channel blocker), and amiloride (Na/H antiporter inhibitor). Application of Ca-chelator EGTA (ethylene glycol-bis(b-aminoethylether)-N,N,N',N'-tetraacetic acid) and HS scavenger hypotaurine abolished the effect of Ca, suggesting the involvement of Ca and HS in the alleviation of NaCl stress. Moreover, use of EGTA and HT also substantiates the downstream functioning of HS during Ca-mediated regulation of plant adaptive responses to NaCl stress. To sum up, present findings reveal the association of Ca and HS signaling in the regulation of ion homeostasis and antioxidant defense during K-deficient NaCl stress.
本研究报告了钙（Ca）和硫化氢（HS）相互作用在豇豆幼苗缺钾条件下短期（24 小时）和长期（72 小时）NaCl 胁迫下的作用。数据分析表明，在短期 NaCl 胁迫下，K 含量的初始下降导致 Ca 和 HS 水平升高，同时抗氧化系统得到改善，活性氧（ROS）生成减少。在长期 NaCl 胁迫下，K 含量进一步下降对植物有害，导致 K/Na 比值降低。随后，抗氧化系统下降，ROS 和甲基乙二醛含量过度积累，膜损伤增加。然而，用 Ca 补充幼苗根部会通过增强半胱氨酸池来增强 HS 的生物合成。本研究结果表明，Ca 和 HS 的协同作用诱导 H-ATPase 活性，从而产生 H 梯度，进而诱导 Na/H 反向转运系统，加速 K 内流和 Na 外流。所有这些共同导致更高的 K/Na 比值、抗氧化防御系统的激活以及 Ca 补充胁迫幼苗中氧化还原平衡和膜完整性的维持。使用偏钒酸钠（质膜 H-ATP 酶抑制剂）、四乙铵氯化物（K 通道阻断剂）和氨氯吡咪（Na/H 反向转运体抑制剂）验证了 Ca 和 HS 在调节 Na/H 反向转运系统中的作用。用 Ca 螯合剂 EGTA（乙二醇双（β-氨基乙基醚）-N，N，N'，N'-四乙酸）和 HS 清除剂次牛磺酸处理后，Ca 的作用被消除，这表明 Ca 和 HS 参与了减轻 NaCl 胁迫。此外，EGTA 和 HT 的应用也证实了 HS 在 Ca 介导的植物对 NaCl 胁迫适应反应调节中的下游作用。综上所述，本研究揭示了 Ca 和 HS 信号在 K 缺乏条件下调节离子稳态和抗氧化防御中的相关性。
