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Elucidation of mechanisms regulating expression of a phytoalexin biosynthetic gene cluster in rice

水稻植物抗毒素生物合成基因簇表达调控机制的阐明

基本信息

批准号：
18580102
负责人：
YAMANE Hisakazu
金额：
$ 2.49万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

We found that two P450 genes (CYP99A2 and CYP99A3) and a putative dehydrogenase gene (AK103462) forms a gene cluster on chromosome 4 of the rice genome together with two diterpene cyclase genes that are involved in biosynthesis of momilactones. In addition, the five clustered genes were coordinately induced after treatment with a chitin oligosaccharide elicitor in suspension-cultured rice cells, suggesting that the momilactone biosynthesis genes are clustered on chromosome 4.On the basis of the above background, this project aimed to demonstrate the presence of a momilactone biosynthetic gene cluster and elucidate regulatory mechanisms for coordinate expression of the gene cluster. We indicated that AK103462 encodes momilactone A synthase, and that the double knockdown of CYP99A2 and CYP99A3 specifically suppressed the elicitor inducible production of momilactones. We thus demonstrated that a momilactone biosynthetic gene cluster consisting of four or five genes is present on chromosome 4 in rice. In addition, we identified an elicitor-inducible basic leucine zipper (bZIP) transcription factor, OsTGAP1, which coordinately regulates the expression of all five genes in the momilactone biosynthetic gene cluster. We also showed that OsTGAP1 can influence the expression of a phytocassane biosynthetic gene and an upstream methylerythritol phosphate (MEP) pathway gene. We thus indicated that OsTGAP1 functions as a key regulator of the coordinated transcription of genes involved in inductive diterpenoid phytoalexins production in rice.All the studies presented here give us important basic information to clarify regulatory mechanisms for production of diterpenoid phytoalexins in rice.

我们发现两个P450基因（CYP99A2和CYP99A3）和一个推测的脱氢酶基因（AK103462）与两个参与momilactones生物合成的二萜环化酶基因一起在水稻基因组的第4染色体上形成一个基因簇。此外，几丁质寡糖诱导子处理水稻悬浮细胞后，5个基因簇被协同诱导，表明龟鳖内酯生物合成基因被聚集在4号染色体上。基于上述背景，本研究旨在证明龟鳖内酯生物合成基因簇的存在，并阐明该基因簇协同表达的调控机制。我们发现AK103462编码momilactone A合成酶，并且CYP99A2和CYP99A3的双敲低特异性地抑制了momilactones的诱导子诱导的产生。因此，我们证明了水稻第4号染色体上存在由四个或五个基因组成的豆蔻内酯生物合成基因簇。此外，我们确定了一个激发子诱导的碱性亮氨酸拉链（bZIP）转录因子，OsTGAP1，协调调节所有五个基因的表达momilactone生物合成基因簇。我们还发现OsTGAP 1可以影响植物卡桑生物合成基因和上游甲基异丙基磷酸（MEP）途径基因的表达。以上结果表明OsTGAP 1是水稻诱导型二萜类植物抗毒素产生相关基因协同转录的关键调控因子，为阐明水稻诱导型二萜类植物抗毒素产生的调控机制提供了重要的基础信息。