The WRKY6 Transcription Factor Modulates PHOSPHATE1 Expression in Response to Low Pi Stress in Arabidopsis
The WRKY6 Transcription Factor Modulates PHOSPHATE1 Expression in Response to Low Pi Stress in Arabidopsis
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DOI：
10.1105/tpc.108.064980
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发表时间：
2009-11-01
期刊：
影响因子：
11.6
通讯作者：
Wu, Wei-Hua
中科院分区：
文献类型：
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作者：
Chen, Yi-Fang;Li, Li-Qin;Wu, Wei-Hua
拟南芥WRKY家族由74个成员组成，其中一些成员参与植物对生物和非生物胁迫的应答。本研究表明WRKY 6通过调控PHOSPHATE 1（PHO 1）的表达参与了拟南芥对低磷胁迫的响应。WRKY 6过表达株系与pho 1突变体相似，对低磷胁迫更敏感，与野生型幼苗和wrky 6 -1突变体相比，地上部中的磷含量更低。免疫沉淀实验表明WRKY 6可以与PHO 1启动子的两个W盒结合。RNA凝胶印迹和β-葡萄糖醛酸酶活性测定表明，PHO 1表达在WRKY 6过表达株系中被抑制，而在wrky 6 -1突变体中被增强。低Pi处理减少了WRKY 6与PHO 1启动子的结合，这表明WRKY 6对PHO 1的调节是Pi依赖性的，并且低Pi处理可以释放对PHO 1表达的抑制。蛋白质凝胶印迹分析表明，低磷诱导的WRKY 6蛋白表达量的下降可被26 S蛋白酶体抑制剂MG 132抑制，表明低磷诱导的PHO 1阻遏物释放可能是由26 S蛋白酶体介导的蛋白质水解作用引起的。此外，WRKY 42还显示与PHO 1启动子的W盒结合并抑制PHO 1表达。我们的研究结果表明，WRKY 6和WRKY 42参与拟南芥响应低磷胁迫的PHO 1表达的调节。
Arabidopsis thaliana WRKY family comprises 74 members and some of them are involved in plant responses to biotic and abiotic stresses. This study demonstrated that WRKY6 is involved in Arabidopsis responses to low-Pi stress through regulating PHOSPHATE1 (PHO1) expression. WRKY6 overexpression lines, similar to the pho1 mutant, were more sensitive to low Pi stress and had lower Pi contents in shoots compared with wild-type seedlings and the wrky6-1 mutant. Immunoprecipitation assays demonstrated that WRKY6 can bind to two W-boxes of the PHO1 promoter. RNA gel blot and beta-glucuronidase activity assays showed that PHO1 expression was repressed in WRKY6-overexpressing lines and enhanced in the wrky6-1 mutant. Low Pi treatment reduced WRKY6 binding to the PHO1 promoter, which indicates that PHO1 regulation by WRKY6 is Pi dependent and that low Pi treatment may release inhibition of PHO1 expression. Protein gel blot analysis showed that the decrease in WRKY6 protein induced by low Pi treatment was inhibited by a 26S proteosome inhibitor, MG132, suggesting that low Pi-induced release of PHO1 repression may result from 26S proteosome-mediated proteolysis. In addition, WRKY42 also showed binding to W-boxes of the PHO1 promoter and repressed PHO1 expression. Our results demonstrate that WRKY6 and WRKY42 are involved in Arabidopsis responses to low Pi stress by regulation of PHO1 expression.