摘要
草甘膦 (N phosphonomethyl glycine ,glyphosate)毒性作用机理是竞争性抑制莽草酸途径中的 5 -烯醇丙酮莽草酸 - 3-磷酸合成酶 (5 -enolpyruvyl shikimate - 3- phosphatesynthase ,简称EPSP合成酶 )的活性。EPSP合成酶是植物和微生物体内芳香族氨基酸 (包括色氨酸、酪氨酸、苯丙氨酸等 )生物合成过程中的一个关键酶。该酶由aroA基因编码。抗草甘膦微生物或植物中EPSP合成酶基因的核苷酸序列在相同或相近位点发生了突变。将编码EPSP合成酶的突变基因导入大豆和烟草等作物中 ,均能获得转基因的抗草甘膦作物。草甘膦的生物降解途径主要有两条 ,C N断裂生成氨甲基磷酸 (AMPA)或C P键断裂生成肌氨酸 (sarcosine) ,然后两种中间代谢物进一步代谢为磷酸。
Glyphosate (N phosphonomethyl glycine) competitively inhibits the activity of 5-enolpyruvyl shikimate-3-phosphate synthase (EPSP Synthase) in the shikimic acid pathway. EPSP synthase encoded by aroA is a critical enzyme involved in the biosynthesis of aromatic amino acids, such as tryptophan, tyrosine and phenylalanine, in bateria and plants. There are two major metabolic pathways found in microbes for glyphosate detoxification. The first involves oxidative cleavage of the nitrogen carbon bond to yield aminomethylphophonic acid (AMPA), which can be further degraded to inorganic phosphate. A second pathway involves the breaking of the phosphorus carbon bond by a novel C P lyase to generate sarcosine, which can be further metabolized. Glyphosate tolerance has been achieved in crops by overexpressing EPSP synthase or introducing glyphosate resistant aroA gene as well as genes involved in glyphosate metabolism.
出处
《分子植物育种》
CAS
CSCD
2003年第4期435-442,共8页
Molecular Plant Breeding
基金
国家转基因植物研究与产业化专项课题(J00-A-010)
国家973”课题(001 CB108904)
国家“863”课题(2001AA214231)资助。
