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VB12 不依赖型蛋氨酸合成酶广泛存在于高等植物中 ,它可催化高半光氨酸甲基化而生成蛋氨酸 ,为生物体内的甲基化反应和多胺、乙烯的合成提供中间产物。以水稻品种日本晴为材料 ,在碱性条件下利用cDNA RAPD法 ,在水稻中首次报道了VB12 不依赖型蛋氨酸合成酶基因的克隆和表达。结果表明 ,VB12 不依赖型蛋氨酸合成酶cDNA基因全长为 2 74 0bp ,在水稻基因组中以单或低拷贝存在 ,编码 76 5个氨基酸 ,与Mesembryanthemumcystallinum(U84 889)和Cathararanthusroseus (X83499)的同源性分别为 92 %和 83%。水稻在受到碳酸钠胁迫 12h和 2 4h后 ,其转录较氯化钠明显增强 ,而到 4 8h后下降 ,暗示它可能与水稻的盐碱适应性有关。
VB12-independent methionine synthetase is widely found in higher plants. It catalyzes the methylation of homocysteine to produce methionine, which provides an intermediate for the methylation in vivo and the synthesis of polyamines and ethers. The rice variety Nipponbare was used as a material to clone and express the VB12-independent methionine synthase gene in rice under the alkaline conditions for the first time using the cDNA RAPD method. The results showed that the full-length cDNA of the VB12-independent methionine synthetase gene was 2 74 0 bp in length and contained a single or low copy in the genome of rice, which encodes a protein of 76 5 amino acids, which is homologous to the homology of Mesembryanthemum cystallinum (U84 889) and Cathararanthus roseus (X83499) Sexuality was 92% and 83% respectively. After 12 h and 24 h after sodium carbonate stress, the transcripts of rice increased significantly compared with those of sodium chloride, and decreased after 48 h, suggesting that it may be related to the adaptability of rice to salinity and alkalinity.