Isolation and functional characterization of a cinnamate 4-hydroxylase promoter from Populus tomentosa

Abstract

Abstracts Cinnamate 4-hydroxylase (C4H) plays key roles in the phenylpropanoid and lignin biosynthesis pathway. A putative C4H promoter fragment was isolated from genomic DNA of Populus tomentosa by PCR. PC4H-GUS construct was made and introduced to tobacco plants via Agrobacterium-mediated transformation. Fluorometric and histochemical GUS analysis showed that the expression of a C4H-GUS fusion product was temporally and spatially specific. It was mainly expressed in the lignified tissues and its activity gradually increased from the first to nine internodes in stems of tobacco, preceding the lignin deposition. GUS staining revealed that C4H-GUS expression was also inductive by wounding. C4H promoter fused to antisense CCoAOMT cDNA was used for manipulating lignin biosynthesis in transgenic tobacco. Experiments using transgenic plants demonstrated that the expression of the fusion gene could effectively reduce lignin content in plants without any pronounced effect on plant growth and the carbon allocation to carbohydrate pool. These results suggest that the C4H promoter from P. tomentosa could be applied in genetically improving wood quality.