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Analysis of starch-to-sucrose transition mechanism in germinating rice seed and its application

水稻种子发芽过程中淀粉-蔗糖转化机理分析及其应用

基本信息

批准号：
12660071
负责人：
MITSUI Toshiaki
金额：
$ 2.24万
依托单位：
Niigata University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

Aim of this research project is to clarify the starch-to-sucrose transition mechanism in germinating rice seed and to establish control system of seed germination. The results obtained in this research period are as follow:1. Temporal, special and hormone-regulated expression of α-amylase and UDP-glucose pyrophosphorylase (UGPase) in germinating rice seeds: UGPase was concluded to be house-keeping enzyme in the scutellar and aleurone tissues. Temporal and spatial expressions of α-amylase I-1 and II-4 were essentially identical in the aleurone layer, although these were distinguishable in the embryo tissues at the early stage of germinatioa It was found that the post-transcriptional regulation of expression of α-amylase II-4, that lacks the gibberellin (GA) response cis-element in the promoter region of the gene, by GA operates in the aleurone layer of germinating rice seed, which is mediated by Ca^<2+> and calmodulin.2. Involvement of histone acetylation in transcription of α-amylase genes: A potent inhibitor for histone deacetylase, Trichostatin A increased the level of α-amylase mRNA in the aleuome without GA, suggesting that the histone acetylation is involved in the regulation of α-amylase gene expression.3. Proteome analysis of scuteller tissues: In the scutellar tissues of germinating rice seeds, several proteins that exhibited the time-dependent and abscisic acid (ABA)-inducible expression were listed up. Glycolitic enzymes, such as phosphoglycerate mutase, glyceraldehydes-3P dehydrogenase, etc., were identified in these proteins. GS-129, one of the listed proteins exhibited the following characteristics: (a) GS-129 tightly associated with cell wall materials, (b) GS-129 was glycoprotein bearing both N-linked and O-linked saccharide chains, (c) GS-129 was suggested to be a possible xylan hydrolyzing enzyme.

本研究旨在阐明水稻种子萌发过程中淀粉转化为蔗糖的机理，建立水稻种子萌发调控体系。本研究取得的主要成果如下：1.α-淀粉酶和UDP-葡萄糖焦磷酸化酶（UGPase）在水稻种子萌发过程中的时间性、特异性和表达调控：UGPase是盾片和糊粉层组织中的管家酶。α-淀粉酶I-1和II-4在糊粉层中的时空表达基本相同，但在萌发早期的胚组织中是有区别的。研究发现，α-淀粉酶II-4基因启动子区缺乏赤霉素（GA）反应顺式元件，GA对萌发水稻种子糊粉层的作用是由Ca^<2+>和钙调蛋白介导的。2.组蛋白乙酰化参与α-淀粉酶基因的转录：组蛋白去乙酰化酶的抑制剂曲古抑菌素A在不加GA的情况下，能增加α-淀粉酶mRNA的表达，提示组蛋白乙酰化参与了α-淀粉酶基因的表达调控.盾叶组织蛋白质组分析：在水稻种子萌发过程中，盾叶组织中有几种蛋白质表达量随时间变化，且受脱落酸（阿坝）诱导。乙醇酸酶，如磷酸甘油酸脱氢酶、甘油醛-3P脱氢酶等，在这些蛋白质中被识别出来。其中GS-129具有以下特征：（a）GS-129与细胞壁物质紧密结合;（B）GS-129是一种糖蛋白，含有N-和O-糖链;（c）GS-129可能是一种木聚糖水解酶。