Arabidopsis NHX5 and NHX6 are endosomal Na+,K+/H+ antiporters that function in mediating Na+, K+ and pH homeostasis. Here, we report that NHX5 and NHX6 mediate Li+ homeostasis in Arabidopsis. We found that the nhx5 nhx6 double mutant was defective in growth and had a high pale rate under Li+ stress; complementation with either NHX5 or NHX6 restored the growth of the double mutant under LiCl treatments. We further found that CBL3 and CIPK18 collaborate with NHX5 and NHX6 in controlling seedling growth. CBL3 and CIPK18 are involved in the NHX5- and NHX6-mediated response to Li+ stress but not to salt or low K+ stress. In addition, NHX5 and NHX6 coordinate NHX8, a plasma membrane antiporter, in mediating Li+ homeostasis. NHX8 may function differently from NHX5 and NHX6 in mediating Li+ homeostasis. NHX8 was not controlled by CBL3 and CIPK18. Overall, CBL3 and CIPK18 are required for the function of NHX5 and NHX6 in mediating Li+ homeostasis in Arabidopsis.

中文翻译：

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CBL3 和 CIPK18 是 NHX5 和 NHX6 在介导拟南芥中 Li+ 稳态的功能所必需的

拟南芥 NHX5 和 NHX6 是内体 Na+、K+/H+ 逆向转运蛋白，在介导 Na+、K+ 和 pH 稳态中起作用。在这里，我们报告了 NHX5 和 NHX6 介导了拟南芥中的 Li+ 稳态。我们发现 nhx5 nhx6 双突变体在 Li+ 胁迫下生长有缺陷并且具有较高的苍白率；在 LiCl 处理下，与 NHX5 或 NHX6 的互补恢复了双突变体的生长。我们进一步发现 CBL3 和 CIPK18 与 NHX5 和 NHX6 协同控制幼苗生长。CBL3 和 CIPK18 参与 NHX5 和 NHX6 介导的对 Li+ 胁迫的反应，但不参与对盐或低 K+ 胁迫的反应。此外，NHX5 和 NHX6 协调 NHX8，一种质膜反向转运蛋白，介导 Li+ 稳态。NHX8 在介导 Li+ 稳态方面的功能可能与 NHX5 和 NHX6 不同。NHX8 不受 CBL3 和 CIPK18 控制。全面的，