Ramakrishna Priya, Gámez-Arjona Francisco M, Bellani Etienne, Martin-Olmos Cristina, Escrig Stéphane, De Bellis Damien, De Luca Anna, Pardo José M, Quintero Francisco J, Genoud Christel, Sánchez-Rodriguez Clara, Geldner Niko, Meibom Anders
Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
Department of Plant Molecular Biology, Biophore, UNIL-Sorge, University of Lausanne, Lausanne, Switzerland.
Nature. 2025 Jan;637(8048):1228-1233. doi: 10.1038/s41586-024-08403-y. Epub 2025 Jan 15.
Increasing soil salinity causes significant crop losses globally; therefore, understanding plant responses to salt (sodium) stress is of high importance. Plants avoid sodium toxicity through subcellular compartmentation by intricate processes involving a high level of elemental interdependence. Current technologies to visualize sodium, in particular, together with other elements, are either indirect or lack in resolution. Here we used the newly developed cryo nanoscale secondary ion mass spectrometry ion microprobe, which allows high-resolution elemental imaging of cryo-preserved samples and reveals the subcellular distributions of key macronutrients and micronutrients in root meristem cells of Arabidopsis and rice. We found an unexpected, concentration-dependent change in sodium distribution, switching from sodium accumulation in the cell walls at low external sodium concentrations to vacuolar accumulation at stressful concentrations. We conclude that, in root meristems, a key function of the NHX family sodium/proton antiporter SALT OVERLY SENSITIVE 1 (also known as Na/H exchanger 7; SOS1/NHX7) is to sequester sodium into vacuoles, rather than extrusion of sodium into the extracellular space. This is corroborated by the use of new genomic, complementing fluorescently tagged SOS1 variants. We show that, in addition to the plasma membrane, SOS1 strongly accumulates at late endosome/prevacuoles as well as vacuoles, supporting a role of SOS1 in vacuolar sodium sequestration.
土壤盐度增加在全球范围内导致了严重的作物损失；因此，了解植物对盐（钠）胁迫的反应至关重要。植物通过涉及高度元素相互依存的复杂过程进行亚细胞区室化来避免钠毒性。目前用于可视化钠，特别是与其他元素一起可视化的技术，要么是间接的，要么分辨率不足。在这里，我们使用了新开发的低温纳米级二次离子质谱离子微探针，它可以对冷冻保存的样品进行高分辨率元素成像，并揭示拟南芥和水稻根分生组织细胞中关键大量元素和微量元素的亚细胞分布。我们发现钠分布出现了意想不到的浓度依赖性变化，从低外部钠浓度下细胞壁中的钠积累转变为胁迫浓度下液泡中的积累。我们得出结论，在根分生组织中，NHX家族钠/质子反向转运蛋白盐过度敏感1（也称为钠/氢交换蛋白7；SOS1/NHX7）的关键功能是将钠隔离到液泡中，而不是将钠挤出到细胞外空间。使用新的基因组学以及荧光标记的互补SOS1变体证实了这一点。我们表明，除了质膜外，SOS1还强烈积累在晚期内体/前液泡以及液泡中，支持SOS1在液泡钠隔离中的作用。
