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八氢番茄红素合成酶(phytoene synthase,psy)是植物体内类胡萝卜素合成途径中的第一个关键酶。本研究从甘薯高类胡萝卜素新品系渝薯11-10-97中克隆了PSY基因,命名为IbPSY。序列分析显示该基因编码区为1 320 bp,编码的蛋白质含有439个氨基酸,分子量为49.110 k Da,等电点(p I)为9.14。进化分析表明IbPSY与栀子的PSY亲缘关系最近。亚细胞定位结果显示,IbPSY定位于植物细胞的叶绿体。在大肠杆菌PSY基因缺陷型菌株中表达IbPSY,能够使缺陷型菌株合成类胡萝卜素;在拟南芥中超表达IbPSY后,拟南芥叶片中类胡萝卜的含量明显提高;表明获得的IbPSY具有八氢番茄红素合成酶基因的功能。
Phytoene synthase (psy) is the first key enzyme in the carotenoid biosynthesis pathway in plants. In this study, PSY gene was cloned from a new sweetpotato high carotenoid line Yu-shu 11-10-97 and named as IbPSY. Sequence analysis showed that the coding region of this gene was 1 320 bp, encoding a protein of 439 amino acids with a molecular weight of 49.110 kDa and an isoelectric point (pI) of 9.14. Phylogenetic analysis showed that IbPSY has the closest genetic relationship with PSY in gardenia. Subcellular localization results show that IbPSY is located in the chloroplast of plant cells. Expression of IbPSY in E. coli PSY-deficient strains could cause the defective strains to synthesize carotenoids. After over expression of IbPSY in Arabidopsis thaliana, the content of carrot in Arabidopsis leaves was significantly increased. The obtained IbPSY has octahydrol Lycopene synthase gene function.