权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Exploration of molecular bases of polyamine's defensive roles against environmental stresses in plants

多胺对植物环境胁迫防御作用的分子基础探索

基本信息

批准号：
21380063
负责人：
KUSANO Tomonobu
金额：
$ 11.9万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2009
资助国家：
日本
起止时间：
2009 至 2011
项目状态：
已结题

项目摘要

In plants, polyamines function in cell division, growth and differentiation because the polyamine contents were found to be higher in actively dividing cells and in reproductive organs. Expression of the genes encoding polyamine biosynthesis enzymes is often enhanced in abiotic and biotic stress condition. Thus polyamines are expected to function for defending host plants against various environmental stresses. Before starting this project, the applicant did two important findings in plant polyamine research ; i. e.,(1)spermine-deficient mutant Arabidopsis plant became hypersensitive to high salinity and dehydration stresses, suggesting that spermine has a defensive role against these two stresses.(2)spermine has a signaling role to evoke the expression of a subset of genes involved in pathogen defense. In December, 2007, a research group reported that ACL5 gene which was previously thought to encode a spermine synthase, encodes a thermospermine (an isomer of spermine)synthase. With th … More is background, first we established a method to separate those two tetraamines, spermine and thermospermine. Second we analyzed the spatio-temporal expression of spermine synthase gene and thermospermine synthase gene in Arabidopsis by monitoring β-glucuronidase reporter gene expression under the promoters of these genes in Arabidopsis. In spermine-signaling pathway, the involvement of polyamine oxidase(s)is strongly suggested. Third, therefore, characterization of polyamine oxidase (PAO)genes of Arabidopsis thaliana and Oryza sativa was performed. In Arabidopsis, four of the PAO genes were cloned into Escherichia coli expression vector. All of the recombinat PAOs catalyzed the back-conversion reaction but not the polyamine terminal catabolism reaction. Rice genome contains 7 PAO genes. Of them, at least 3 PAO genes catalyzed the polyamine back-conversion reaction, strongly suggesting that rice plant has two catabolic pathways for polyamines. Fourth, spermine has a defensive role in heat shock response (submitted, revision prepared). We also demonstrated that bZIP60, one of the master genes in the unfolded stress response (UPR), is upregulated by spermine. The product of bZIP60 resides in endoplasmic reticulum (ER)in physiological condition, while, once UPR is triggered, it is shown that bZIP60 transcript is spliced by RNase activity of IRE1. Fifth, bZIP60 transcript is spliced by spermine and the resulting transcript produces the active bZIP60 protein which targets into the nucleus (manuscript in preparation). In this activation process, IRE1 is also involved. Lastly we showed that thermospermine has a similar signaling activity to induce the defense genes and inhibits phytoviral particle multiplication as spermine does. Less

在植物中，多胺在细胞分裂、生长和分化中起作用，因为多胺在活跃分裂的细胞和生殖器官中含量较高。在非生物和生物胁迫条件下，多胺合成酶基因的表达往往增强。因此，多胺被认为具有保护寄主植物免受各种环境胁迫的作用。在开始这个项目之前，申请人在植物多胺研究中有两个重要发现：例如，（1）精胺缺陷突变体拟南芥对高盐和脱水胁迫表现出高度敏感性，表明精胺对这两种胁迫具有防御作用。（2）精胺具有信号传导作用，以引起参与病原体防御的基因子集的表达。2007年12月，一个研究小组报道，以前被认为编码精胺合酶的ACL 5基因编码热精胺（精胺的异构体）合酶。与th ...更多信息为背景，我们首先建立了精胺和热精胺的分离方法。其次，通过检测拟南芥精胺合酶基因和热精胺合酶基因启动子下的β-葡萄糖醛酸酶报告基因的表达，分析了这两个基因在拟南芥中的时空表达。在精胺信号通路中，多胺氧化酶的参与是强烈建议。第三，因此，多胺氧化酶（PAO）基因的拟南芥和水稻进行了表征。在拟南芥中，四个PAO基因被克隆到大肠杆菌表达载体中。所有的重组PAO催化的反转化反应，但不是多胺末端催化反应。水稻基因组含有7个PAO基因。其中，至少有3个PAO基因催化多胺的反转化反应，这表明水稻对多胺有两条分解代谢途径。第四，精胺在热休克反应中具有防御作用（已提交，修订稿已准备好）。我们还证明，bZIP 60，在未折叠的应激反应（UPR）的主基因之一，是上调精胺。bZIP 60的产物在生理条件下存在于内质网（ER）中，而一旦UPR被触发，则显示bZIP 60转录物通过IRE 1的RNA酶活性被剪接。第五，bZIP 60转录物被精胺剪接，所得转录物产生靶向细胞核的活性bZIP 60蛋白（手稿在制备中）。在这个激活过程中，IRE 1也参与其中。最后，我们发现热精胺具有与精胺相似的诱导防御基因和抑制植物病毒颗粒增殖的信号传导活性。少