辣椒素生物合成相关基因研究进展

Research Advances in Capsaicin Biosynthesis Genes

辣椒素是一种仅在辣椒属植物中合成的十分重要的次生代谢产物,其生物合成受遗传和环境的双重影响。辣椒中辣椒素含量的高低决定辣度的大小。辣椒素类物质是由香草基胺与C9-C11支链脂肪酸合成,前者来源苯丙氨基酸途径,后者来源于缬氨酸或亮氨酸。参与辣椒素合成途径中目前已知的酶有:苯丙氨酸裂解酶(PAL)、肉桂酸水解酶(Ca4H)、对香豆酸水解酶(C3H)、咖啡酸转甲氧基酶(COMT)、氨基转移酶(pAMT)、支链氨基酸转移酶(BCAT)、β-酮脂酰-ACP合酶(KAS)、酰基运载蛋白(ACL)、酰基-ACP-硫酯酶(FAT)、去饱和酶、酰基CoA合成酶(ACS)和辣椒素合成酶(capsaicin synthase,CS)等。目前,参与辣椒素类物质生物合成的PAL、Ca4H、COMT、pAMT、KAS、ACL、FAT、ACS和CS基因已经克隆出来,相应功能也做了初步的研究。综述了辣椒素生物合成相关基因的克隆和特性研究的最新进展,并探讨了辣椒素基因研究存在的问题和今后研究的方向。

Capsaicin is a very important secondary metabolite that is peculiar to capsicum. The content of capsaicin would determine the degree of hot pepper pungency. Capsaicin biosynthesis is regulated by genetics and environment in hot pepper. It has been proposed that capsaicinoids are synthesized by the condensation of vanillylamine with C9 to Cll isotype branched-chain fatty acids; the former is derived from phenylpropanoid pathway, the latter from valinc or leucine. 11 enzymes which putatively catalyze different reactions involved in capsaicinoids production have been described, i.e., phenylalanine ammonialyase （PAL）, einnamic acid 4-hydroxylase （CagH）, coumaroyl shikimate/quinate 3-hydroxylase （Ca3H）, caffeic acid O-methyl transferase （COMT）, putative aminotransferase （pAMT）, branched-chain amino acid transferase （BCAT）, ^-ketoacyl ACP synthase （KAS）, acyl carrier protein （ACL）, acyl-ACP thioesterase （FAT）, acyl-CoA synthetase （ACS） and capsaicin synthase （CS）. The genes encoding the PAL,CadH,COMT,pAMT,KAS,ACL,FA T,ACS and CS have been cloned and some of them have been functionally characterized. In this review, the cloning and characterization of several genes related to capsaicinoid biosynthetic pathway were summarized, some problems and tendency of gene research about capsaicin biosynthesis were also discussed.