| Lignin is the second abundant organics in the terrestrial vascular plants, which is crucial for the plants to adapt the environment during evolution. Cinnamoyl -CoA reductase (CCR) is a key enzyme in the lignin biosynthesis pathway, catalyze the conversion of cinnamoyl-CoA esters to their cinnamaldehydes respectively. A 1017bp cDNA of CCR was isolated from populus tomentosa.Sense, antisense and a full-length repeat constructs of CCR were introduced into tobacco (Nicotiana tabacum) to regulate the gene expression. The transgenic plants exhibited correlation between the gene transcript and the enzyme activity. All the down-regulation plants showed a lower transcript levels and catalyze ability. The accumulation of soluble phenolic acid in cell wall of the down-regulated lines indicates that the carbon flow of lignin synthesis might be blocked. Lignin content was evaluated by the standard Klason lignin method and Acetyl bromide method, The severely down-regulated line A1 showed almost 50% decrease either in Klason lignin or bromoacetylated lignin. The changes of the cell wall properties in transformants suggested that the CCR might be a good control point in lignin pathway regulation. |
