AUTHOR=Chen Qi , Xu Kai , Xu Yan , Ji Dehua , Chen Changsheng , Xie Chaotian , Wang Wenlei TITLE=Na+/K+-ATPase regulates the K+/Na+ homeostasis in the intertidal macroalgae, Neoporphyra haitanensis, in response to salt stress JOURNAL=Frontiers in Plant Science VOLUME=13 YEAR=2023 URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1040142 DOI=10.3389/fpls.2022.1040142 ISSN=1664-462X 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.