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 indicated
Antisense CCoAOMT cDNA of Chinese white poplar( Populus tomentosa) was transformed into tobacco W38 mediated by Agrobacterium tumefaciens. The results of PCR, PCR-Southern and Northern dot analysis indicated that the antisense CCoAOMT cDNA was integrated in the genome of the transgenic tobacco and expressed at transcriptional level. The basal stems of the 3-month-old transgenic plants growing in the greenhouse were cut off and dried for Klason lignin analysis. Lignin content in most of the transgenic plants declined compared with the control plants, and one of them, the lignin content decreased by 37%. Our results suggest that the suppression of endogenous CCoAOMT expression can reduce lignin content of the plants effectively.
ZHAO Hua-yan, WEI Jian-hua, LIU Hui-rong, ZHU Zhi-qing and SONG Yan-ru( Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, P.R.China
