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Properties of Guard-Cell Chloroplasts and their Role in Stomatal Opening

保卫细胞叶绿体的特性及其在气孔开放中的作用

基本信息

批准号：
01540572
负责人：
SHIMAZAKI Ken-ichiro
金额：
$ 1.09万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01540572/
关键词：
Stomata Protoplasts Guard cell RuBP carboxylase Chloroplast 光合成炭酸固定反応 PGA@DHAPシャトルソラマメ

项目摘要

Enzyme activities of Calvin-Benson cycle were investigated in guard cell protoplasts from Vicia faba L. Evidence for the key enzyme of ribulose 1,5-bisphosphate carboxylase (RuBPase) was obtained in guard cell protoplasts by immunoblotting using the antibody of RuBPase, by the activity measured by methods of enzyme coupling and ^<14>CO_2 incorporation. All these measurements revealed that the activity of RuBPase in guard cells was about 40 % of that in mesophyll cells on a chlorophyll basis. Other enzymes which constitute the Calvin-Benson cycle, such as Phosphoglycerate Kinase (PGAK), NADP-glyceraldehyde phosphate dehydrogenase (NADP-GAPD), Triose Phosphate Isomerase (TPI), Fructose Bisphosphatase (FBPase) were also found in Vicia guard cell protoplasts. Among these enzymes, the enzymes related closely to the PGA/DHAP shuttle which mediate the transfer of ATP and reducing equivalents from chloroplasts to cytosol had very high activities, indicating that guard cells utilize the shuttle very largely. The RuBPase activity of guard cell protoplasts was 30% of that of mesophyll protoplasts on a chlorophyll basis; however, the O_2 evolution rate was 3 times higher in guard cell protoplasts than in mesophyll protoplasts. Irreversible NADP-GAPD was found in high activity in guard cell protoplasts. From these results I concluded that guard cells utilize a considerable proportion of reducing equivalents from water for reactions other than CO_2 fixation.

研究了蚕豆保卫细胞原生质体Calvin-Benson循环酶活性。用抗核酮糖1，5-二磷酸羧化酶（RuBPase）抗体进行免疫印迹，通过酶偶联法和CO_2掺入法测定RuBPase活性，获得了保卫细胞原生质体中存在RuBPase的证据<14>。所有这些测量表明，保卫细胞中RuBP酶的活性约为叶肉细胞中RuBP酶活性的40%。在蚕豆保卫细胞原生质体中还发现了其他组成Calvin-Benson循环的酶，如磷酸甘油酸激酶（PGAK）、NADP-甘油醛磷酸脱氢酶（NADP-GAPD）、磷酸丙糖异构酶（TPI）、果糖二磷酸酶（FBPase）。在这些酶中，与PGA/DHAP穿梭体密切相关的介导ATP和还原当量从叶绿体向胞质溶胶转移的酶具有很高的活性，表明保卫细胞对穿梭体的利用程度很高。以叶绿素计，保卫细胞原生质体的RuBP酶活性是叶肉原生质体的30%，但其放氧速率是叶肉原生质体的3倍。在保卫细胞原生质体中发现了高活性的不可逆NADP-GAPD。从这些结果中，我得出结论，保卫细胞利用相当大比例的还原当量从水的反应，而不是固定CO_2。