Potentiation of developmentally regulated plant defense response by AtWRKY18, a pathogen-induced Arabidopsis transcription factor
Potentiation of developmentally regulated plant defense response by AtWRKY18, a pathogen-induced Arabidopsis transcription factor
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DOI：
10.1104/pp.001057
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发表时间：
2002-06-01
期刊：
影响因子：
7.4
通讯作者：
Chen, ZX
中科院分区：
文献类型：
--
作者：
Chen, CH;Chen, ZX
AtWRKY 18是一个由病原菌和水杨酸诱导的拟南芥转录因子，含有植物特异性WRKY锌指DNA结合基序。在本研究中，我们已经转化拟南芥植物与AtWRKY 18花椰菜花叶病毒35 S启动子的控制下。令人惊讶的是，表达高水平AtWRKY 18的转基因植物生长受阻。当以中等水平表达时，AtWRKY 18增强转基因植物中发育调节的防御反应，而不会对植物生长造成实质性的负面影响。从幼苗到成熟期，转AtWRKY 18基因植株的病程相关基因表达量显著增加，对细菌病原菌Pseudomonasalumingae的抗性显著增强，而野生型植株的这些防御反应几乎没有增强。AtWRKY 18增强发育调节的防御反应与水杨酸生物合成的增强无关，但需要抗病调节蛋白NPR 1/NIM 1。因此，AtWRKY 18可以正向调节防御相关基因的表达和抗病性。为了研究AtWRKY 18的调控表达，我们已经确定了一组WRKY结合位点的基因的启动子，并证明他们作为负调控元件AtWRKY 18的诱导表达。这些负顺式作用元件可以防止AtWRKY 18在植物防御反应的激活过程中过表达，这可能对植物生长有害，如从异位表达转基因的转基因植物推断的。
AtWRKY18 is a pathogen- and salicylic acid-induced Arabidopsis transcription factor containing the plant-specific WRKY zinc finger DNA-binding motif. In the present study, we have transformed Arabidopsis plants with AtWRKY18 under control of the cauliflower mosaic virus 35S promoter. Surprisingly, transgenic plants expressing high levels of AtWRKY18 were stunted in growth. When expressed at moderate levels, AtWRKY18 potentiated developmentally regulated defense responses in transgenic plants without causing substantial negative effects on plant growth. As they grew from seedling to mature stages, transgenic AtWRKY18 plant showed marked increase in the expression of pathogenesis-related genes and resistance to the bacterial pathogen Pseudomonas syringae, whereas wild-type plants exhibited little enhancement in these defense responses. Potentiation of developmentally regulated defense responses by AtWRKY18 was not associated with enhanced biosynthesis of salicylic acid but required the disease resistance regulatory protein NPR1/NIM1. Thus, AtWRKY18 can positively modulate defense-related gene expression and disease resistance. To study the regulated expression of AtWRKY18, we have identified a cluster of WRKY binding sites in the promoter of the gene and demonstrated that they acted as negative regulatory elements for the inducible expression of AtWRKY18. These negative cis-acting elements may prevent overexpression of AtWRKY18 during the activation of plant defense responses that could be detrimental to plant growth as inferred from the transgenic plants ectopically expressing the transgene.