Obtaining the transgenic poplars with low lignin content through down-regulation of4CL

Abstract

The antisense4CL (4-coumarate: CoA ligase) gene was transformed into triploid Chinese white poplar (Populus tomentosa) mediated byAgrobacterium tumefaciens. PCR and Southern blot analysis indicated that antisense4CL gene had been integrated into the genome of the transgenic Chinese white poplars. The antisense gene had also been expressed, which was indicated by RT-PCR and Western analysis. Klason lignin content assay showed that repression of4CL expression could result in remarkable reduction of lignin content in transgenic poplars, with most reduction of 41.73% compared with that of wild type in this paper. But there is no significant difference in holocellulose content between transgenic and wild poplars. We considered that 4CL might not be the metabolism control point between lignin and carbohydrate biosynthesis. The stems of transgenic poplars displayed red-brown color with different levels after the bark was peeled, while those of untransformed plants were white. No visible differences in growth and development were observed between transgenic and wild plants. Wiesner reaction analysis of the transgenic plant stems with reduced lignin content exhibited red color, while that of untransformed plant was typically purple-red.