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Wall yielding of stem segments in adaptive growth recovery after osmotic stress

渗透胁迫后适应性生长恢复中茎段的壁产量

基本信息

批准号：
09640769
负责人：
KATOU Kiyoshi
金额：
$ 2.05万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09640769/
关键词：
osmotic stress adaptive growth effective turgor turgor yield threshold yieldin cDNA cloning cowpea 壁伸展壁展性プロトンポンプ壁辰性膨圧 IAA cycloheximide breferdin A ミトリササゲ

项目摘要

Regulation of the in vivo wall yielding properties of the cell wall of Vigna hypocotyl segments during adaptive osmotic recovery of growth after osmotic stress was investigated by successive measurements using pressure-jump method. In the absence of IAA, cell wall extensibility showed no significant change under osmotic stress but effective turgor (P-Y) reduced to nearly zero, resulting in no growth recovery. In the presence of IAA, cell wall extensibility slightly decreased eve though growth recovered distinctly. Once extinguished effective turgor, however, fully recovered. It is effective turgor (driving force) that regulates wall yielding in growth recovery under osmotic stress. Intracellular pressure measurements revealed that the recovery of effective turgor is not caused by the regulation of P but Y. Y is always adjusted to about 60 kPa below the P that is comparable to the elevated effective turgor during IAA-induced growth promotion.Wall bound protein yieldin that regulates pH-dependent yield threshold tension of glycerinated hollow cylinder (GHC) of cowpea hypocotyl was isolated from elongating hypocotyls of cowpea. Thus, cDNA of yieldin was cloned with RTPCR. The cDNA for yieldin contained an open reading frame of 981 base pairs encoding 327 amino acids. Recombinant yieldin expressed with E. coli showed potent activity of regulating the pH-dependent yield threshold tension of GHC. A homology search revealed that yieldin was homologous to acidic class III chitinase and concanavalin B. The chitinase activity, however, showed no direct relation to the yieldin activity. Mechanism of yieldin action remains to be studied.

采用压力跃变法研究了豇豆下胚轴切段在渗透胁迫后生长适应性渗透恢复过程中细胞壁屈服特性的调节。在缺乏IAA的情况下，细胞壁伸展性在渗透胁迫下没有显著变化，但有效膨压（P-Y）几乎为零，导致生长不能恢复。在IAA存在下，细胞壁伸展性略有下降，但生长明显恢复。然而，一旦有效膨压消失，则完全恢复。在渗透胁迫下，植物生长恢复过程中，有效膨压（驱动力）调节着细胞壁屈服。细胞内压的测定表明，有效膨压的恢复不是由P的调节引起的，而是由Y的调节引起的。Y总是被调节到比P低60 kPa左右，这与IAA诱导的生长促进过程中升高的有效膨压相当。从豇豆下胚轴伸长过程中分离到壁结合蛋白yieldin，它调节豇豆下胚轴甘油空心圆柱体（GHC）的pH依赖性屈服阈值张力。通过RTPCR方法克隆了yieldin的cDNA。yieldin的cDNA包含一个981个碱基对的开放阅读框架，编码327个氨基酸。用E.大肠杆菌中的GHC对pH依赖的屈服阈值张力具有较强的调节活性。同源性分析表明yieldin与酸性III类几丁质酶和伴刀豆球蛋白B同源。几丁质酶活性与产素活性无直接关系。屈服作用的机理有待研究。