Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong 518055, China; Max-Planck Institute for Plant Breeding Research, Cologne 50829, Germany.
Max-Planck Institute for Plant Breeding Research, Cologne 50829, Germany; Institute of Biochemistry, University of Cologne, Cologne 50923, Germany; Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
Cell. 2022 Sep 1;185(18):3341-3355.e13. doi: 10.1016/j.cell.2022.07.012. Epub 2022 Aug 22.
The extracellular pH is a vital regulator of various biological processes in plants. However, how plants perceive extracellular pH remains obscure. Here, we report that plant cell-surface peptide-receptor complexes can function as extracellular pH sensors. We found that pattern-triggered immunity (PTI) dramatically alkalinizes the acidic extracellular pH in root apical meristem (RAM) region, which is essential for root meristem growth factor 1 (RGF1)-mediated RAM growth. The extracellular alkalinization progressively inhibits the acidic-dependent interaction between RGF1 and its receptors (RGFRs) through the pH sensor sulfotyrosine. Conversely, extracellular alkalinization promotes the alkaline-dependent binding of plant elicitor peptides (Peps) to its receptors (PEPRs) through the pH sensor Glu/Asp, thereby promoting immunity. A domain swap between RGFR and PEPR switches the pH dependency of RAM growth. Thus, our results reveal a mechanism of extracellular pH sensing by plant peptide-receptor complexes and provide insights into the extracellular pH-mediated regulation of growth and immunity in the RAM.
细胞外 pH 是植物中各种生物过程的重要调节剂。然而，植物如何感知细胞外 pH 值仍然不清楚。在这里，我们报告植物细胞表面肽受体复合物可以作为细胞外 pH 传感器。我们发现，模式触发免疫（PTI）显著使根顶端分生组织（RAM）区域的酸性细胞外 pH 值碱化，这对于根分生组织生长因子 1（RGF1）介导的 RAM 生长是必不可少的。细胞外碱化通过 pH 传感器磺酪氨酸逐渐抑制酸性依赖的 RGF1与其受体（RGFRs）之间的相互作用。相反，细胞外碱化通过 pH 传感器 Glu/Asp 促进植物激发肽（Peps）与其受体（PEPRs）的碱性依赖结合，从而促进免疫。RGFR 和 PEPR 之间的结构域交换改变了 RAM 生长对 pH 值的依赖性。因此，我们的结果揭示了植物肽受体复合物感知细胞外 pH 值的机制，并为细胞外 pH 值介导的 RAM 中生长和免疫的调节提供了新的视角。
