瑞士联邦理工学院Anders Meibom、Priya Ramakrishna和洛桑大学Niko Geldner小组合作在研究中取得进展。他们利用元素冷冻成像发现液泡中钠的积累依赖SOS1。该项研究成果发表在2025年1月15日出版的《自然》上。

研究人员使用新开发的冷冻纳米级二次离子质谱离子微探针（可对低温保存的样品进行高分辨率元素成像），揭示了拟南芥和水稻根分生组织细胞中，关键宏量营养元素和微量营养元素的亚细胞分布。意外的，研究发现钠分布发生了浓度依赖性变化，在外部钠离子浓度较低时，钠离子在细胞壁中积累；而在钠离子浓度较高时，钠在液泡中积累。

研究人员发现在根分生组织中，NHX家族钠/质子拮抗剂SALT OVERLY SENSITIVE 1（又称 Na⁺/H⁺ 交换子 7；SOS1/NHX7）的一个关键功能是将钠封闭在液泡中，而不是将钠挤出到细胞外空间。使用新的基因组互补荧光标记SOS1变体证实了这一点。研究发现，除质膜外，SOS1还会在晚期内膜/前液泡以及液泡中大量积聚，这支持SOS1在液泡钠螯合中的作用。

据介绍，在全球范围内，土壤盐度的增加会造成重大的作物损失。因此，了解植物对盐（钠）胁迫的反应非常重要。植物通过与高度元素相互依存的复杂过程进行亚细胞区隔，从而避免钠毒性。目前可视化钠和其他元素的技术要么是间接的，要么分辨率低。

附：英文原文

Title: Elemental cryo-imaging reveals SOS1-dependent vacuolar sodium accumulation

Author: Ramakrishna, Priya, Gmez-Arjona, Francisco M., Bellani, Etienne, Martin-Olmos, Cristina, Escrig, Stphane, De Bellis, Damien, De Luca, Anna, Pardo, Jos M., Quintero, Francisco J., Genoud, Christel, Snchez-Rodriguez, Clara, Geldner, Niko, Meibom, Anders

Issue&Volume: 2025-01-15

Abstract: 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 microprobe1, 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.

DOI: 10.1038/s41586-024-08403-y

Source: https://www.nature.com/articles/s41586-024-08403-y