Lignin biosynthesis by suppression of two O-methyl-transferases  

作　　者：ZHAO Huayan WEI Jianhua ZHANG Jinyu LIU Huirong WANG Tai SONG Yanru 

机构地区：[1]Institute of Botany,Chinese Academy of Sciences,Beijing 100093,China [2]Beijing Center of Agro-Biotechnology,Beijing Institute of Agriculture and Forestry,Beijing 100089,China [3]不详

出　　处：《Chinese Science Bulletin》2002年第13期1092-1095,1145,共5页

基　　金：This work was supported by the National Natural Science Foundation of China (Grant No. 30170783); the State "863" High-Tech Program (Grant No. 2001AA212151).

摘　　要：Caffeic acid O-methyltransferase (COMT) and caffeoyl-CoA-3-O-methyltransferase (CCoAOMT) genes encode two methyltransferases at different substrate levels in lignin biosynthesis. We constructed two single antisense expression vectors containing the cDNA of COMT or CCoAOMT genes and one dual antisense expression vector containing cDNAs of both OMTs genes. The antisense constructs were transferred into tobacco mediated by Agrobac-terium tumefacience. PCR-Southern analysis indicated that antisense cDNAs had been integrated into the genome of the transgenic tobacco. The antisense genes were also expressed at transcriptional level displayed by Northern dot analysis. Klason lignin assay of 3-month-old transgenic tobaccos showed that repression in COMT or CCoAOMT alone could result in reduction of lignin content, more reduction was caused by suppression in CCoAOMT than in COMT. Furthermore, simultaneous suppression of both COMT and CCoAOMT resulted in more reduction than that of single gene, which indicatedCaffeic acid O-methyltransferase (COMT) and caffeoyl-CoA-3-O-methyltransferase (CCoAOMT) genes encode two methyltransferases at different substrate levels in lignin biosynthesis. We constructed two single antisense expression vectors containing the cDNA of COMT or CCoAOMT genes and one dual antisense expression vector containing cDNAs of both OMTs genes. The antisense constructs were transferred into tobacco mediated by Agrobac-terium tumefacience. PCR-Southern analysis indicated that antisense cDNAs had been integrated into the genome of the transgenic tobacco. The antisense genes were also expressed at transcriptional level displayed by Northern dot analysis. Klason lignin assay of 3-month-old transgenic tobaccos showed that repression in COMT or CCoAOMT alone could result in reduction of lignin content, more reduction was caused by suppression in CCoAOMT than in COMT. Furthermore, simultaneous suppression of both COMT and CCoAOMT resulted in more reduction than that of single gene, which indicated the cooperation of COMT and CCoAOMT. Histochemical staining showed that downregu-lated COMT led to the remarkable reduction of syringyl lignin. These data demonstrated that repression of CCoAOMT was an effective way to alter lignin biosynthesis in transgenic plants for improving the property of pulping.

关 键 词：COMT CCOAOMT ANTISENSE RNA LIGNIN histochemi-cal staining. 

分 类 号：Q753[生物学—分子生物学]