CaHDZ27, a Homeodomain-Leucine Zipper I Protein, Positively Regulates the Resistance to Ralstonia solanacearum Infection in Pepper
CaHDZ27, a Homeodomain-Leucine Zipper I Protein, Positively Regulates the Resistance to Ralstonia solanacearum Infection in Pepper
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CaHDZ27 是一种同源结构域亮氨酸拉链 I 蛋白，可正向调节辣椒对青枯菌感染的抵抗力
DOI：
10.1094/mpmi-06-17-0130-r
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Shuilin He
中科院分区：
文献类型：
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作者：
Mou Shaoliang;Liu Zhiqin;Gao Feng;Yang Sheng;Su Meixia;Shen Lei;Wu Yang;Shuilin He
同源结构域亮氨酸拉链 I 类 (HD-Zip I) 转录因子在植物对非生物胁迫的反应中具有功能特征，但它们在植物免疫中的作用却知之甚少。在此，从辣椒 (Capsicum annum) 中分离出 HD-Zip I 基因 CaHZ27，并对其在辣椒免疫中的作用进行了表征。实时定量聚合酶链反应表明，CaHDZ27 是通过接种青枯菌和外源应用茉莉酸甲酯、水杨酸或乙烯利诱导转录的。 CaHDZ27-绿色荧光蛋白融合蛋白专门针对细胞核。染色质免疫沉淀表明 CaHDZ27 与 9 bp 假回文元件 (CAATAATTG) 结合，并以 CAATAATTG 依赖性方式触发 β-葡萄糖醛酸酶表达。病毒诱导的 CaHDZ27 基因沉默显着减弱了辣椒植物对青枯菌的抗性，并下调了防御相关标记基因，包括 CaHIR1、CaACO1、CaPR1、CaPR4、CaPO2 和 CaBPR1。相比之下，CaHDZ27 的瞬时过度表达引发了由超敏反应介导的强烈细胞死亡，并上调了测试的免疫相关标记基因。烟草中的异位 CaHDZ27 表达增强了其对青枯菌的抗性。这些结果共同表明 CaHDZ27 在辣椒对青枯菌的抗性中起到正调节作用。双分子荧光互补和免疫共沉淀测定表明CaHDZ27单体相互结合，并且这种结合通过接种青枯菌而显着增强。我们推测CaHZ27的同二聚化可能在辣椒对青枯菌的反应中发挥作用，需要进一步的直接证据来证实。
Homeodomain-leucine zipper class I (HD-Zip I) transcription factors have been functionally characterized in plant responses to abiotic stresses, but their roles in plant immunity are poorly understood. Here, a HD-Zip I gene, CaHZ27, was isolated from pepper (Capsicum annum) and characterized for its role in pepper immunity. Quantitative real-time polymerase chain reaction showed that CaHDZ27 was transcriptionally induced by Ralstonia solanacearum inoculation and exogenous application of methyl jasmonate, salicylic acid, or ethephon. The CaHDZ27-green fluorescent protein fused protein was targeted exclusively to the nucleus. Chromatin immunoprecipitation demonstrated that CaHDZ27 bound to the 9-bp pseudopalindromic element (CAATAATTG) and triggered beta-glucuronidase expression in a CAATAATTG-dependent manner. Virus-induced gene silencing of CaHDZ27 significantly attenuated the resistance of pepper plants against R. solanacearum and downregulated defense-related marker genes, including CaHIR1, CaACO1, CaPR1, CaPR4, CaPO2, and CaBPR1. By contrast, transient overexpression of CaHDZ27 triggered strong cell death mediated by the hypersensitive response and upregulated the tested immunity-associated marker genes. Ectopic CaHDZ27 expression in tobacco enhances its resistance against R. solanacearum. These results collectively suggest that CaHDZ27 functions as a positive regulator in pepper resistance against R. solanacearum. Bimolecular fluorescence complementation and coimmunoprecipitation assays indicate that CaHDZ27 monomers bind with each other, and this binding is enhanced significantly by R. solanacearum inoculation. We speculate that homodimerization of CaHZ27 might play a role in pepper response to R. solanacearum, further direct evidence is required to confirm it.