Diterpenoid phytoalexin factor, a bHLH transcription factor, plays a central role in the biosynthesis of diterpenoid phytoalexins in rice
Diterpenoid phytoalexin factor, a bHLH transcription factor, plays a central role in the biosynthesis of diterpenoid phytoalexins in rice
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DOI：
10.1111/tpj.13065
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发表时间：
2015-12-01
期刊：
影响因子：
7.2
通讯作者：
Mori, Masaki
中科院分区：
文献类型：
--
作者：
Yamamura, Chihiro;Mizutani, Emi;Mori, Masaki
水稻（Oryza sativa）产生的二萜类植物抗毒素（DPs）、豆蔻内酯和植物卡桑烷是主要的植物抗毒素。稻瘟病菌侵染、紫外线照射和氯化铜处理均可诱导水稻中DPs的积累。在这里，我们描述了一个水稻转录因子命名为二萜类植物抗毒素因子（DPF），这是一个基本的螺旋-环-螺旋（bHLH）转录因子。编码DPF的基因主要在根和穗中表达，并且在叶片中被稻瘟病感染、氯化铜或UV诱导。在DPF过量表达和DPF敲除水稻中，所有DP生物合成基因的表达以及momilactones和phytocassanes的积累分别显著增加和减少。这些结果清楚地表明，DPF通过DP生物合成基因的转录调控正向调节DP的积累，并在水稻DP的生物合成中起着核心作用。此外，DPF激活了二磷酸铜合酶2（CPS 2）和细胞色素P450单加氧酶99 A2（CYP 99 A2）的启动子，其产物分别参与植物卡桑和momilactones的生物合成。在CPS 2上游区域的N盒中的突变，几种动物bHLH转录因子结合，降低CPS 2转录，表明DPF通过N盒正向调节CPS 2转录。此外，DPF通过N-box部分调节CYP 99 A2。这项研究表明，DPF作为一个主转录因子在DP的生物合成。
Rice (Oryza sativa) produces diterpenoid phytoalexins (DPs), momilactones and phytocassanes as major phytoalexins. Accumulation of DPs is induced in rice by blast fungus infection, copper chloride or UV light. Here, we describe a rice transcription factor named diterpenoid phytoalexin factor (DPF), which is a basic helix-loop-helix (bHLH) transcription factor. The gene encoding DPF is expressed mainly in roots and panicles, and is inducible in leaves by blast infection, copper chloride or UV. Expression of all DP biosynthetic genes and accumulation of momilactones and phytocassanes were remarkably increased and decreased in DPF over-expressing and DPF knockdown rice, respectively. These results clearly demonstrated that DPF positively regulates DP accumulation via transcriptional regulation of DP biosynthetic genes, and plays a central role in the biosynthesis of DPs in rice. Furthermore, DPF activated the promoters of COPALYL DIPHOSPHATE SYNTHASE2 (CPS2) and CYTOCHROME P450 MONOOXYGENASE 99A2 (CYP99A2), whose products are implicated in the biosynthesis of phytocassanes and momilactones, respectively. Mutations in the N-boxes in the CPS2 upstream region, to which several animal bHLH transcription factors bind, decreased CPS2 transcription, indicating that DPF positively regulates CPS2 transcription through the N-boxes. In addition, DPF partly regulates CYP99A2 through the N-box. This study demonstrates that DPF acts as a master transcription factor in DP biosynthesis.