A feedback loop between CaWRKY41 and H2O2 coordinates the response to Ralstonia solanacearum and excess cadmium in pepper
A feedback loop between CaWRKY41 and H2O2 coordinates the response to Ralstonia solanacearum and excess cadmium in pepper
复制标题
CaWRKY41 和 H2O2 之间的反馈回路协调对青枯菌和辣椒中过量镉的反应
DOI：
10.1093/jxb/erz006
复制
发表时间：
2019-02-15
影响因子：
6.9
通讯作者：
He, Shuilin
中科院分区：
文献类型：
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作者：
Dang, Fengfeng;Lin, Jinhui;He, Shuilin
WRKY转录因子参与了植物对镉的免疫和应答；然而，这些过程之间相互作用的机制尚不清楚。本文研究了WRKY III组转录因子CaWRKY41在辣椒（Capsicum annuum）抗病原菌Ralstonia solanacearum免疫和Cd胁迫应答中的作用。CaWRKY41在Cd暴露、接种茄青霉和H2O2处理下转录上调。病毒诱导的CaWRKY41沉默增强了拟南芥的Cd耐受性和敏感性，而异源过表达CaWRKY41则削弱了拟南芥的Cd耐受性，增强了Cd和锌（Zn）的吸收和H2O2的积累。在cawrky41过表达的拟南芥植物中，活性氧清除酶编码基因下调，而锌转运蛋白和H2O2产生酶编码基因上调。与这些发现一致，阳离子过氧化物酶3 （ocp3）过表达突变体H2O2水平升高，对Cd胁迫的敏感性增强。上述结果表明，H2O2积累与CaWRKY41上调之间存在一个正反馈回路，协调了辣椒对茄青霉接种和Cd暴露的响应。这一机制可能通过增加锌转运体对Cd的吸收而降低了对Cd的耐受性，同时增强了对茄青霉的抗性。
WRKY transcription factors have been implicated in both plant immunity and plant responses to cadmium (Cd); however, the mechanism underlying the crosstalk between these processes is unclear. Here, we characterized the roles of CaWRKY41, a group III WRKY transcription factor, in immunity against the pathogenic bacterium Ralstonia solanacearum and Cd stress responses in pepper (Capsicum annuum). CaWRKY41 was transcriptionally up-regulated in response to Cd exposure, R. solanacearum inoculation, and H2O2 treatment. Virus-induced silencing of CaWRKY41 increased Cd tolerance and R. solanacearum susceptibility, while heterologous overexpression of CaWRKY41 in Arabidopsis impaired Cd tolerance, and enhanced Cd and zinc (Zn) uptake and H2O2 accumulation. Genes encoding reactive oxygen species-scavenging enzymes were down-regulated in CaWRKY41-overexpressing Arabidopsis plants, whereas genes encoding Zn transporters and enzymes involved in H2O2 production were up-regulated. Consistent with these findings, the ocp3 (overexpressor of cationic peroxidase 3) mutant, which has elevated H2O2 levels, displayed enhanced sensitivity to Cd stress. These results suggest that a positive feedback loop between H2O2 accumulation and CaWRKY41 up-regulation coordinates the responses of pepper to R. solanacearum inoculation and Cd exposure. This mechanism might reduce Cd tolerance by increasing Cd uptake via Zn transporters, while enhancing resistance to R. solanacearum.