cDNA cloning and functional analysis of 4-coumarate — CoA: ligase (4CL) gene in Chinese white aspen*

cDNA encoding 4-coumarate: CoA ligase (4CL) was isolated from the secondary developing xylem of Chinese white aspen (Populus tomentosa) by RT-PCR for the first time, which was 1619 bp in length. The coding sequence and putative amino acid sequence showed 97. 53 % and 97.00% identity to that of Pt4CLl in quaking aspen (P. tremuloids), respectively. Molecular analysis indicated that 4CL was encoded by multiple genes in P. tomentosa, its mRNA was highly accumulated in xylem and the expression of 4CL revealed a biphasic pattern in one growing season, almost in phase with the expression of other related enzymes in lignin biosynthesis. Transgenic research showed that expression of antisense 4CL cDNA led to the decreasing of lignin content in transgenic tobaccos, among which the average reduction was 10. 3 % and the highest could be up to 18.9%. These data suggested that 4CL gene was a potential gene used in altering lignin biosynthesis by biotechnology for producing new materials of papermaking.