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Study on generation of ascorbic acid-enriched transgenic rice

富含抗坏血酸的转基因水稻的产生研究

基本信息

批准号：
13660095
负责人：
ESAKA Muneharu
金额：
$ 2.3万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13660095/
关键词：
L-ascorbic acid rice L-galactono-1, 4-lactone dehydrogenase transgenic plant tobacco root vitamin C UV 遺伝子組換え植物 cDNA ガラクトノラクトン脱水素酵素

项目摘要

L-ascorbic acid (AsA), Called vitamin Cm is accumulated up to millimolar concentrations in plant tissues. L-Galactono-1, 4-lactone dehydrogenase (GalLDH; EC 1.3.2.3) is the final enzyme in L-ascorbic acid (AsA) biosynthesis pathway of plant, and it catalyzes the oxidation of L-galactono-1, 4-lactone to AsA. AsA-overproducing transgenic tobacco BY-2 cell-lines were generated by over-expression of the GalLDH cDNA under the control of cauliflower mosaic virus 35S promoter. Over-expression of GalLDH mRNA let to increases in the GalLDH activity and fine protein. AsA levels of this transgenic tobacco were detected about 6-18 fold as much as wild type (W) cells. Interestingly in these AsA-enriched transgenic cell cultures, cell browning markedly restrained, suggesting that a higher level of AsA suppressed senescence of these transgenic cells. Furthermore, these AsA over-producing transgenic cells could acquire resistance against paraquat that produces some active oxygen species. Thus, AsA-overproducing transgenic tobacco cells were suggested to have a higher ability to scavenge active oxygen species. Rice GalLDH cDNA was also clones. The expression of GalLDH was positively correlated with ascorbic acid content of rice. In rice, the biosynthetic pathway of ascorbic acid was investigated by supplement experiment of 9 precursors of ascorbic acid. In rice root, an increase in ascorbic acid content stimulated root elongation. Furthermore, the increase in ascorbic acid inhibited degradation of leaf chlorophyll caused by UV.

L-抗坏血酸(AsA)，又称维生素Cm，在植物组织中积累到毫摩尔浓度。L-半乳糖基-1，4-内酯脱氢酶(GalLDH；EC 1.3.2.3)是植物L-抗坏血酸(AsA)生物合成途径中的终末酶，它催化L-半乳糖基-1，4-内酯氧化生成抗坏血酸。在花椰菜花叶病毒35S启动子的控制下，通过GalLDH基因的高表达，获得了AsA-高产转基因烟草BY-2细胞系。GalLDH mRNA过表达可使GalLDH活性和细小蛋白含量增加。这种转基因烟草的AsA水平大约是野生型(W)细胞的6-18倍。有趣的是，在这些富含AsA的转基因细胞培养中，细胞褐变明显受到抑制，这表明较高水平的AsA抑制了这些转基因细胞的衰老。此外，这些高产量的转基因细胞可能会对产生某些活性氧物种的百草枯产生抗性。因此，过量生产AsA的转基因烟草细胞具有更强的清除活性氧的能力。水稻GalLDH基因也是克隆的。GalLDH的表达与水稻体内抗坏血酸含量呈正相关。通过对9种抗坏血酸前体的补充试验，研究了水稻体内抗坏血酸的生物合成途径。在水稻根中，抗坏血酸含量的增加促进了根的伸长。此外，抗坏血酸的增加抑制了紫外线引起的叶片叶绿素的降解。