Identification and Characterization of ANAC042, a Transcription Factor Family Gene Involved in the Regulation of Camalexin Biosynthesis in Arabidopsis
Identification and Characterization of ANAC042, a Transcription Factor Family Gene Involved in the Regulation of Camalexin Biosynthesis in Arabidopsis
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DOI：
10.1094/mpmi-09-11-0244
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发表时间：
2012-05-01
影响因子：
3.5
通讯作者：
Ohta, Daisaku
中科院分区：
文献类型：
--
作者：
Saga, Hirohisa;Ogawa, Takumi;Ohta, Daisaku
Camalexin 是拟南芥中主要的植物抗毒素。已经阐明了几乎完整的camalexin生物合成酶集，但关于调节camalexin生物合成的分子机制仅可获得有限的信息。在这里，我们证明 ANAC042 是 NAM、ATAF1/2 和 CUC2 (NAC) 转录因子家族基因的成员，参与camalexin生物合成诱导。 ANAC042 的 T-DNA 插入突变体未能以野生型达到的水平积累 camalexin，并且对球状链格孢感染高度敏感。 camalexin 生物合成基因 CYP71A12、CYP71A13 和 CYP71B15/PAD3 在突变体中未完全诱导，表明 camalexin 缺陷至少部分是这些 P450 基因表达水平降低的结果。 β-葡萄糖醛酸酶 (GUS) 报告基因检测证明了 ANAC042 响应不同病原体感染的组织特异性诱导。细菌鞭毛蛋白 (FIg22) 在根伸长区（camalexin 生物合成位点）诱导 ANAC042 表达，并且在一般激酶抑制剂 (K252a)、Ca2+-螯合剂 (BAPTA) 或茉莉酸甲酯存在时，诱导作用被消除。 GUS-报告基因检测显示，在乙烯不敏感的 ein2-1 背景中，FIg22 依赖性 ANAC042 表达受到抑制，但在水杨酸生物合成缺陷的 sid2-2 植物中则没有。我们讨论 ANAC042 作为关键转录因子，参与先前未知的诱导拟南芥植物抗毒素生物合成的调节机制。
Camalexin is the major phytoalexin in Arabidopsis. An almost complete set of camalexin biosynthetic enzymes have been elucidated but only limited information is available regarding molecular mechanisms regulating camalexin biosynthesis. Here, we demonstrate that ANAC042, a member of the NAM, ATAF1/2, and CUC2 (NAC) transcription factor family genes, is involved in camalexin biosynthesis induction. T-DNA insertion mutants of ANAC042 failed to accumulate camalexin at the levels achieved in the wild type, and were highly susceptible to Alternaria brassicicola infection. The camalexin biosynthetic genes CYP71A12, CYP71A13, and CYP71B15/PAD3 were not fully induced in the mutants, indicating that the camalexin defects were at least partly a result of reduced expression levels of these P450 genes. beta-Glucuronidase (GUS)-reporter assays demonstrated tissue-specific induction of ANAC042 in response to differential pathogen infections. Bacterial flagellin (FIg22) induced ANAC042 expression in the root-elongation zone, the camalexin biosynthetic site, and the induction was abolished in the presence of either a general kinase inhibitor (K252a), a Ca2+-chelator (BAPTA), or methyl jasmonate. The GUS-reporter assay revealed repression of the FIg22-dependent ANAC042 expression in the ethylene-insensitive ein2-1 background but not in sid2-2 plants defective for salicylic acid biosynthesis. We discuss ANAC042 as a key transcription factor involved in previously unknown regulatory mechanisms to induce phytoalexin biosynthesis in Arabidopsis.