Tabata Kazufumi, Takaoka Takahiko, Esaka Muneharu
Faculty of Applied Biological Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, 739-8528, Japan.
Phytochemistry. 2002 Nov;61(6):631-5. doi: 10.1016/s0031-9422(02)00367-9.
GDP-D-mannose pyrophosphorylase (GMPase) and L-galactono-1, 4-lactone dehydrogenase (GalLDH) are key enzymes in L-ascorbic acid (AsA) biosynthesis of plants, and a full-length cDNA for GMPase was isolated from tobacco using PCR. Additionally, expression of GMPase, GalLDH and other AsA-related enzymes was examined in tobacco tissues and cultured BY-2 cells, and the relationship between their expression patterns and AsA content is discussed. It was found that the expression of GalLDH and GMPase mRNAs was markedly suppressed by loading AsA, suggesting that AsA concentration in the cells may regulate AsA biosynthesis. Moreover, the expression of GMPase and GalLDH mRNAs in tobacco leaf also suggested that AsA biosynthesis may be induced by light.
GDP-D-甘露糖焦磷酸化酶（GMPase）和L-半乳糖酸-1,4-内酯脱氢酶（GalLDH）是植物L-抗坏血酸（AsA）生物合成中的关键酶，利用PCR从烟草中分离出了GMPase的全长cDNA。此外，还检测了烟草组织和培养的BY-2细胞中GMPase、GalLDH及其他与AsA相关酶的表达情况，并讨论了它们的表达模式与AsA含量之间的关系。研究发现，加载AsA可显著抑制GalLDH和GMPase mRNA的表达，这表明细胞内AsA浓度可能调节AsA的生物合成。此外，烟草叶片中GMPase和GalLDH mRNA的表达也表明，光照可能诱导AsA的生物合成。
