CaCDPK15 positively regulates pepper responses to Ralstonia solanacearum inoculation and forms a positive-feedback loop with CaWRKY40 to amplify defense signaling.
CaCDPK15 positively regulates pepper responses to Ralstonia solanacearum inoculation and forms a positive-feedback loop with CaWRKY40 to amplify defense signaling.
复制标题
CaCDPK15 正向调节辣椒对青枯菌接种的反应，并与 CaWRKY40 形成正反馈环，以放大防御信号
DOI：
10.1038/srep22439
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发表时间：
2016-03-01
影响因子：
4.6
通讯作者：
He S
中科院分区：
文献类型：
--
作者：
Shen L;Yang S;Yang T;Liang J;Cheng W;Wen J;Liu Y;Li J;Shi L;Tang Q;Shi W;Hu J;Liu C;Zhang Y;Mou S;Liu Z;Cai H;He L;Guan D;Wu Y;He S
CaWRKY40是辣椒（Capsicum annum）对青枯菌（Ralstonia solanacearum）接种（RSI）反应的正调控因子，但其潜在机制尚不清楚。在这里，我们的功能特点CaCDPK15在防御信号介导的CaWRKY40。在CaCDPK15启动子（pCaCDPK15）中鉴定了病原体响应TGA、W和ERE盒，并且pCaCDPK15驱动的GUS表达响应于RSI和外源施用的水杨酸、茉莉酸甲酯、脱落酸和乙烯利而显著增强。病毒诱导的CaCDPK15基因沉默（VIGS）显著增加了辣椒对RSI的易感性，并下调了免疫相关标志物CaNPR1，CaPR1和CaDEF 1。相反，瞬时CaCDPK15过表达显著激活过敏反应相关的细胞死亡，上调免疫相关标记基因，上调CaWRKY40表达，并在其靶基因的启动子处富集CaWRKY40。虽然CaCDPK15未能与CaWRKY40相互作用，但通过染色质免疫沉淀检测到CaWRKY40与pCaCDPK15的直接结合，这在辣椒植物中被RSI显著增强。这些综合结果表明，辣椒中的RSI诱导CaCDPK15并间接激活下游CaWRKY40，这反过来又增强了CaCDPK15的表达。这种正反馈回路将放大针对RSI的防御信号，并有效地激活强大的植物免疫力。
CaWRKY40 is a positive regulator of pepper (Capsicum annum) response to Ralstonia solanacearum inoculation (RSI), but the underlying mechanism remains largely unknown. Here, we functionally characterize CaCDPK15 in the defense signaling mediated by CaWRKY40. Pathogen-responsive TGA, W, and ERE boxes were identified in the CaCDPK15 promoter (pCaCDPK15), and pCaCDPK15-driven GUS expression was significantly enhanced in response to RSI and exogenously applied salicylic acid, methyl jasmonate, abscisic acid, and ethephon. Virus-induced gene silencing (VIGS) of CaCDPK15 significantly increased the susceptibility of pepper to RSI and downregulated the immunity-associated markers CaNPR1, CaPR1, and CaDEF1. By contrast, transient CaCDPK15 overexpression significantly activated hypersensitive response associated cell death, upregulated the immunity-associated marker genes, upregulated CaWRKY40 expression, and enriched CaWRKY40 at the promoters of its targets genes. Although CaCDPK15 failed to interact with CaWRKY40, the direct binding of CaWRKY40 to pCaCDPK15 was detected by chromatin immunoprecipitation, which was significantly potentiated by RSI in pepper plants. These combined results suggest that RSI in pepper induces CaCDPK15 and indirectly activates downstream CaWRKY40, which in turn potentiates CaCDPK15 expression. This positive-feedback loop would amplify defense signaling against RSI and efficiently activate strong plant immunity.