JXB：西北寒旱所、兰大丨FADs在植物胁迫耐受中的功能（钙信号）

作者：中科院西北生态环境资源研究所石玉兰、兰州大学生科院安黎哲

标题：Integrated regulation triggered by a cryophyte ω-3 desaturase gene confers multiple-stress tolerance in tobacco

主题：ω-3脂肪酸去饱和酶在植物胁迫耐受中的功能

期刊：Journal of Experimental Botany

影响因子：5.354

检测指标：Ca2+

ω-3 fatty acid desaturases (FADs) are thought to  contribute to plant stress tolerance mainly through linolenic acid  (C18:3)-induced membrane stabilization, but a comprehensive analysis of  their roles in stress adaptation is lacking.

Here, we isolated a microsomal ω-3 FAD gene (CbFAD3)  from a cryophyte (Chorispora bungeana) and elucidated its functions in  stress tolerance. CbFAD3, exhibiting a high identity to Arabidopsis  AtFAD3, was up-regulated by abiotic stresses. Its functionality was  verified by heterogonous expression in yeast. Overexpression of CbFAD3  in tobacco constitutively increased C18:3 in both leaves and roots,  which maintained the membrane fluidity, and enhanced plant tolerance to  cold, drought, and salt stresses.

Notably, the constitutively increased C18:3 induced a  sustained activation of plasma membrane Ca2+-ATPase, thereby, changing  the stress induced Ca2+ signaling. The reactive oxygen species (ROS)  scavenging system, which was positively correlated with the level of  C18:3, was also activated in the transgenic lines.

Microarray analysis showed that CbFAD3-overexpressing  plants increased the expression of stressresponsive genes, most of  which are affected by C18:3, Ca2+, or ROS. Together, CbFAD3 confers  tolerance to multiple stresses in tobacco through the C18:3-induced  integrated regulation of membrane, Ca2+, ROS, and stress-responsive  genes. This is in contrast with previous observations that simply  attribute stress tolerance to membrane stabilization.

ω-3脂肪酸去饱和酶（FADs）被认为主要通过亚麻酸（C18：3）诱导的膜稳定作用促进植物抗逆性，但缺乏对其在胁迫适应中的作用的综合分析。

在这里，我们从冷冻植物（Chorispora bungeana）中分离出微粒体ω-3  FAD基因（CbFAD3），并阐明其在胁迫耐受中的功能。表现出与拟南芥AtFAD3高度同一性的CbFAD3被非生物胁迫上调。其功能通过酵母中的异源表达来验证。烟草中CbFAD3的过量表达在叶和根中组成性地增加了C18：3，这保持了膜的流动性，并增强了植物对冷，干旱和盐胁迫的耐受性。

值得注意的是，组成型增加的C18：3诱导质膜Ca2+-ATPase的持续活化，从而改变应激诱导的Ca2+信号传导。与C18：3水平正相关的活性氧（ROS）清除系统也在转基因系中被激活。

微阵列分析显示过表达CbFAD3的植物增加了应激反应基因的表达，其中大多数受C18：3，Ca2+或ROS的影响。   CbFAD3一起通过C18：3诱导的膜，Ca2+，ROS和应激反应基因的整合调节赋予对烟草中多种胁迫的耐受性。这与先前的观察结果形成对比，之前的观察结果仅仅将压力耐受性归因于膜稳定。