Zhu Xiaoyang, Robe Eugénie, Jomat Lucile, Aldon Didier, Mazars Christian, Galaud Jean-Philippe
Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, CNRS, UPS, 24, chemin de Borde-Rouge, Auzeville, BP, Castanet-Tolosan, France.
Institut Jacques Monod, UMR 7592, CNRS-Université Paris Diderot, 15 rue Hélène Brion, Paris Cédex, France.
Plant Cell Physiol. 2017 Feb 1;58(2):307-319. doi: 10.1093/pcp/pcw189.
Calcium is a universal second messenger involved in various cellular processes including plant development and stress responses. Its conversion into biological responses requires the presence of calcium sensor relays such as calmodulin (CaM) and calmodulin-like (CML) proteins. While the role of CaM is well described, the functions CML proteins remain largely uncharacterized. Here, we show that Arabidopsis CML8 expression is strongly and transiently induced by Pseudomonas syringae, and reverse genetic approaches indicated that the overexpression of CML8 confers on plants a better resistance to pathogenic bacteria compared with wild-type, knock-down and knock-out lines, indicating that CML8 participates as a positive regulator in plant immunity. However, this difference disappeared when inoculations were performed using bacteria unable to inject effectors into a plant host cell or deficient for some effectors known to target the salicylic acid (SA) signaling pathway. SA content and PR1 protein accumulation were altered in CML8 transgenic lines, supporting a role for CML8 in SA-dependent processes. Pathogen-associated molecular pattern (PAMP) treatments with flagellin and elf18 peptides have no effects on CML8 gene expression and do not modify root growth of CML8 knock-down and overexpressing lines compared with wild-type plants. Collectively, our results support a role for CML8 in plant immunity against P. syringae.
钙是一种通用的第二信使，参与包括植物发育和应激反应在内的各种细胞过程。其转化为生物反应需要钙传感器中继蛋白的存在，如钙调蛋白（CaM）和类钙调蛋白（CML）。虽然CaM的作用已得到充分描述，但CML蛋白的功能在很大程度上仍未明确。在这里，我们表明拟南芥CML8的表达受到丁香假单胞菌的强烈且短暂诱导，反向遗传学方法表明，与野生型、敲低和敲除系相比，CML8的过表达赋予植物对病原菌更好的抗性，这表明CML8作为植物免疫的正调控因子发挥作用。然而，当使用无法将效应子注入植物宿主细胞或某些已知靶向水杨酸（SA）信号通路的效应子缺陷的细菌进行接种时，这种差异消失了。CML8转基因系中SA含量和PR1蛋白积累发生了变化，支持CML8在SA依赖过程中的作用。用鞭毛蛋白和elf18肽进行的病原体相关分子模式（PAMP）处理对CML8基因表达没有影响，与野生型植物相比，也不会改变CML8敲低和过表达系的根生长。总体而言，我们的结果支持CML8在植物对丁香假单胞菌的免疫中发挥作用。
