烟草查尔酮异构酶基因2(NtCHI2)功能分析

Functional analysis of chalcone isomerase gene 2(NtCHI2)in tobacco

烟草查尔酮异构酶(Chalcone isomerase,CHI)是黄酮类代谢的一个关键酶,烟草中有两个基因拷贝(NtCHI1、NtCHI2),相关研究多集中在NtCHI1基因,对NtCHI2的研究较少。为研究烟草NtCHI2的功能,主要以NtCHI2的过表达和干扰植株叶片为材料,进行了实时定量PCR和CHI活性分析以及芸香苷含量检测,同时进行了NtCHI2体外表达蛋白的酶活分析。结果表明:NtCHI2体外表达蛋白具有查尔酮异构酶活性;过表达株系中NtCHI2的表达量升高5~75倍,但CHI酶活性和芸香苷含量基本没有变化;干扰株系中NtCHI2的表达量降至70%,CHI酶活性和芸香苷含量分别降低50%和90%。烟草NtCHI2参与芸香苷的合成代谢调控,在一定程度上NtCHI2基因的表达量和芸香苷的含量正相关。

Chalcone isomerase(CHI)is one of the key enzymes in flavonoid metabolism.In tobacco,two copies of CHI genes,NtCHI1 and NtCHI2,are identified,while little is known on the function of NtCHI2 compared to that of NtCHI1.To study the function of NtCHI2,its rutin content,CHI activity,and NtCHI2 expression level were analyzed for NtCHI2-OE strains and NtCHI2-RNAi strains.We also examined the CHI activity of recombinant NtCHI2 expressed in vitro.The results showed that NtCHI2 had a CHI activity.In the NtCHI2-OE strains,the NtCHI2 expression level was up-regulated by 5-75 folds,however no significant changes in CHI activity and rutin content were detected.In NtCHI2-RNAi strains,the NtCHI2 expression level was down-regulated to 70%,and correspondingly,CHI activity and rutin content decreased by 50%and 90%respectively.NtCHI2 was involved in the metabolic regulation of rutin,and the expression of NtCHI2 was positively correlated with the rutin content to some extent.