Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China.
College of Life Sciences, Capital Normal University, Beijing 100048, China.
Plant Cell. 2023 Mar 29;35(4):1259-1280. doi: 10.1093/plcell/koad014.
Nitrogen (N) and potassium (K) are essential macronutrients for plants. Sufficient N and K uptake from the environment is required for successful growth and development. However, how N and K influence each other at the molecular level in plants is largely unknown. In this study, we found loss-of-function mutation in SLAH3 (SLAC1 HOMOLOGUE 3), encoding a NO3- efflux channel in Arabidopsis thaliana, enhanced tolerance to high KNO3 concentrations. Surprisingly, slah3 mutants were less sensitive to high K+ but not NO3-. Addition of NO3- led to reduced phenotypic difference between wild-type and slah3 plants, suggesting SLAH3 orchestrates NO3--K+ balance. Non-invasive Micro-test Technology analysis revealed reduced NO3- efflux and enhanced K+ efflux in slah3 mutants, demonstrating that SLAH3-mediated NO3- transport and SLAH3-affected K+ flux are critical in response to high K +. Further investigation showed that two K+ efflux channels, GORK (GATED OUTWARDLY-RECTIFYING K+ CHANNEL) and SKOR (STELAR K+ OUTWARD RECTIFIER), interacted with SLAH3 and played key roles in high K+ response. The gork and skor mutants were slightly more sensitive to high K+ conditions. Less depolarization occurred in slah3 mutants and enhanced depolarization was observed in gork and skor mutants upon K+ treatment, suggesting NO3-/K+ efflux-mediated membrane potential regulation is involved in high K+ response. Electrophysiological results showed that SLAH3 partially inhibited the activities of GORK and SKOR in Xenopus laevis oocytes. This study revealed that the anion channel SLAH3 interacts with the potassium channels GORK and SKOR to modulate membrane potential by coordinating N-K balance.
氮（N）和钾（K）是植物必需的大量营养素。从环境中充分吸收 N 和 K 是成功生长和发育所必需的。然而，在植物中，N 和 K 如何在分子水平上相互影响在很大程度上是未知的。在这项研究中，我们发现拟南芥 SLAC1 同源物 3（SLAC1 HOMOLOGUE 3），编码硝酸盐外排通道的功能丧失突变，增强了对高 KNO3 浓度的耐受性。令人惊讶的是，slah3 突变体对高 K+的敏感性降低，但对 NO3-不敏感。添加 NO3-导致野生型和 slah3 植物之间的表型差异减小，表明 SLAH3 协调 NO3--K+平衡。非侵入性微测试技术分析显示 slah3 突变体中 NO3-外排减少和 K+外排增加，表明 SLAH3 介导的 NO3-转运和 SLAH3 影响的 K+通量在高 K+响应中至关重要。进一步的研究表明，两种 K+外排通道，GORK（门控外向整流钾通道）和 SKOR（星状外向整流钾通道），与 SLAH3 相互作用，并在高 K+响应中发挥关键作用。gork 和 skor 突变体对高 K+条件的敏感性略高。在 K+处理后，slah3 突变体中去极化程度较小，而 gork 和 skor 突变体中去极化程度增强，表明 NO3-/K+外排介导的膜电位调节参与高 K+响应。电生理结果表明，SLAH3 部分抑制 Xenopus laevis 卵母细胞中 GORK 和 SKOR 的活性。这项研究揭示了阴离子通道 SLAH3 通过协调 N-K 平衡来调节膜电位，与钾通道 GORK 和 SKOR 相互作用。
