Generation of stress-resistant transgenic tomato containing a large amount of ascorbic acid

人类无法合成抗坏血酸（维生素C），因此依赖植物等外部来源提供。l -抗坏血酸因其在植物中的重要作用和与人类的密切关系而备受关注。它是一种酶辅因子和抗氧化剂，参与植物细胞内许多不同的基本过程，包括激素和细胞壁的生物合成、抗逆性、光保护和细胞生长。已经确定甘露糖参与植物抗坏血酸的生物合成。甘露糖用于生物合成抗坏血酸、糖蛋白、L-蛋白和细胞壁多糖。催化gdp -甘露糖生成的gdp -甘露糖焦磷酸化酶表达的任何变化都可能影响抗坏血酸的生物合成。l -半乳糖通过尚不清楚的步骤被释放，被氧化为l -半乳糖-1,4-内酯，然后通过l -半乳糖-1,4-内酯脱氢酶转化为l -抗坏血酸。对番茄植株的生物合成途径和生物学功能进行了深入的研究。l -半乳糖-1,4-内酯脱氢酶和甘露糖焦磷酸化酶是植物抗坏血酸生物合成途径中的重要酶。从番茄中克隆了编码l -半乳糖-1,4-内酯脱氢酶和甘露糖焦磷酸化酶的cdna并进行了测序。Northern杂交分析表明，它们的相对mRNA水平与番茄组织中抗坏血酸含量的变化相关，表明l -半乳糖-1,4-内酯脱氢酶和gdp -甘露糖焦磷酸化酶参与了抗坏血酸的生物合成。针叶树（Malpighia glabra L.）是已知抗坏血酸（维生素C）最丰富的天然来源之一。因此，抗坏血酸生物合成酶的表达明显高。因此，我挑战产生含有大量抗坏血酸的转基因番茄，其中引入抗坏血酸生物合成酶针叶菌基因并过表达。最后，讨论了通过提高抗坏血酸含量来产生抗环境胁迫转基因番茄的可能性。少

Man is unable to synthesize ascorbic acid (vitamin C) and so depends on external sources such as plants for its supply. L-ascorbic acid attracts so much attention because of its important role in plants and relevance to man. It acts as an enzyme cofactor and an antioxidant and is involved in many different essential processes within the plant cell, including hormone and cell wall biosynthesis, stress resistance, photo-protection and cell growth. It has been established that GDP-D-mannose is involved in plant ascorbic acid biosynthesis. GDP-mannose is used for the biosynthesis of ascorbic acid, glycoprotein, L-fucose and cell wall polysaccharide. Any change in the expression of GDP-mannose pyrophosphorylase catalyzing the formation of GDP-mannose may affect the biosynthesis of ascorbic acid. The L-galactose which is released, through yet unclear steps, is oxidized to L-galactono-1,4-lactone and later converted to L-ascorbic acid by L-galactono-1,4-lactone dehydrogenase.I have investigat … More ed biosynthesis pathway and biological function of tomato plant. L-galactono-1,4-lactone dehydrogenase and GDP-mannose pyrophosphorylase are the vital enzymes in the proposed biosynthetic pathway for ascorbic acid in plants. The cDNAs encoding L-galactono-1,4-lactone dehydrogenase and GDP-mannose pyrophosphorylase have been cloned and sequenced from tomato. Northern hybridization analysis indicated that their relative mRNA levels correlated with the changing ascorbic acid content of tomato tissues, suggesting that L-galactono-1,4-lactone dehydrogenase and GDP-mannose pyrophosphorylase are involved in ascorbic acid biosynthesis.Acerola (Malpighia glabra L.) is one of the richest known natural sources of ascorbic acid (vitamin C). Thus, the expression of ascorbic acid-biosynthesizing enzymes is markedly high. Thus, I challenged to generate transgenic tomato containing a large amount of ascorbic acid in which acerola genes for ascorbic acid-biosynthesizing enzymes are introduced and over-expressed. Finally, the possibility of the generation of transgenic tomato that has resistance to environmental stresses by increasing their ascorbic acid content has been discussed. Less