Functional Analysis Of Lignin Biosynthetic Genes From Poplar And Their Effect On The Biomass Energy Conversion

Lignin has been recognized for its negative impact on cellulosic biofuel production, although it is the major structural component of cell walls of vascular plants. In our previous study, the transgenic poplars expressing anti-sense4-coumarate:CoA ligase (4CL) gene or anti-sense caffeoyl CoA3-O-methyltransferase (CCoAOMT) gene have been developed, and the effects of lignin modification on saccharification of lignocellulosic biomass were analyzed. Results indicated that the lignin concentration of mature wood from transgenic poplar plants was reduced up to10%during five years’growth, and the reduced trend of lignin content remained stable in all transgenic lines. However the suppression of CCoAOMT increased saccharification potential, but4CL down-regulation had no significantly positive effect on saccharification. Sugar yield were negatively correlated with soluble lignin content of dried, extractive-free stem biomass. These results imply that lignin modification can facilitate the process of saccharification for biofuel production in tree crops.MYB transcription factors play an important role in transcriptional regulation of lignin biosynthesis. Bioinformatics and comparative genomics analysis showed that PtoMYB199and PtoMYB125are specifically expressed in xylem and involved in the regulation of the lignin biosynthesis. The subcellular localization and transcriptional activation activity of PtoMYB199and PtoMYB125from populus tomentosa were analyzed, and transgenic Arabidopsis thaliana expressing PtoMYB199and PtoMYB125genes were developed. The phenotype analysis showed that some transgenic lines exhibited leaf curling, this phenotype would be related to the lignin biosynthesis transcriptional regulation of PtoMYB199and PtoMYB125.