The calcium transporter ANNEXIN1 mediates cold‐induced calcium signaling and freezing tolerance in plants

第一作者：Qiangbo Liu

第一单位：中国农业大学

通讯作者：Shuhua Yang

 Abstract 

背景+问题：The transient elevation of cytosolic free calcium concentration ([Ca2+]cyt) induced by cold stress is a well‐established phenomenon; however, the underlying mechanism remains elusive.

主要发现：Here, we report that the Ca2+‐permeable transporter ANNEXIN1 (AtANN1) mediates cold‐ riggered Ca2+ influx and freezing tolerance in Arabidopsis thaliana.

结果1-AtANN1功能缺失：The loss of function of AtANN1 substantially impaired freezing tolerance, reducing the cold‐induced [Ca2+]cyt increase and upregulation of the cold‐ esponsive CBF and COR genes.

结果2-上游激酶蛋白OST1：Further analysis showed that the OST1/SnRK2.6 kinase interacted with and phosphorylated AtANN1, which consequently enhanced its Ca2+ transport activity, thereby potentiating Ca2+ signaling.

结果3-ost1突变体：Consistent with these results and freezing sensitivity of ost1 mutants, the cold‐induced [Ca2+]cyt elevation in the ost1‐3 mutant was reduced.

结果4-OST1-AtANN1：Genetic analysis indicated that AtANN1 acts downstream of OST1 in responses to cold stress.

结论：Our data thus uncover a cascade linking OST1‐AtANN1 to cold‐induced Ca2+ signal generation, which activates the cold response and consequently enhances freezing tolerance in Arabidopsis.

 摘 要 

低温胁迫引起的细胞内游离钙浓度短暂升高是一个已确认的现象；然而，潜在的机制仍然不清楚。本文中，作者发现拟南芥中钙滲透性转运蛋白AtANN1介导了低温诱导的钙离子内流和耐冻性。AtANN1功能突变体使得拟南芥抗冻性受损，减少了低温诱导的胞内游离钙离子增量，并且上调了低温响应基因CBF和COR。进一步的分析显示OST1/SnRK2.6激酶与AtANN1互作，并且磷酸化AtANN1蛋白，从而增强其钙离子转运活性，最终增强了钙离子信号转导。ost1突变体对冻害更加敏感，并且ost1‐3突变体中由低温诱导的胞内游离钙增量减少。遗传分析显示AtANN1响应于低温，作用于OST1基因的下游。本文的数据揭示了拟南芥中一个将OST1‐AtANN1连接到低温诱导的钙离子信号的级联，进而激活了低温响应，并最终增强了抗冻能力。

 通讯作者 

**杨淑华**

doi: https://doi.org/10.15252/embj.2020106862

Journal: the EMBO Journal

Published date: Jan 05, 2021