Na+/K+-ATPase regulates the K+/Na+ homeostasis in the intertidal macroalgae, Neoporphyra haitanensis, in response to salt stress
Qi Chen, Kai Xu, Yan Xu, Dehua Ji, Changsheng Chen, Chaotian Xie, Wenlei Wang
Abstract
In plants under hypersaline stress, the main transporter that extrudes sodium ions (Na + ) is the Na + /H + antiporter SOS1. Different from land plants, the intertidal macroalgae, Neopyropia/Neoporphyra contains an animal-type Na + /K + -ATPase as well as the SOS1 system. However, the contribution of Na + /K + -ATPase to the K + /Na + homeostasis of intertidal macroalgae remains unclear. In this study, we analyzed the function of Na + /K + -ATPase in the response of Neoporphyra haitanensis to salt stress from the perspective of ion transport dynamics. Both the transcript level of NhNKA2 and enzyme activity of Na + /K + -ATPase increased in the early response of N. haitanensis thalli to hypersaline stress. Addition of ouabain, an inhibitor of Na + /K + -ATPase, resulted in Na + accumulation in the cells, severe K + leakage from the thalli, and then remarkably disturbed the K + /Na + homeostasis in N. haitanensis thalli. This disruption might induce a significant decrease in photosynthesis and a severe oxidative damage in thalli. Accordingly, these results suggested that the important role of Na + /K + -ATPase in the resistance of intertidal macroalgae to hypersaline stress, and shed light on the diversity of K + /Na + homeostasis maintenance mechanisms in plants.