Engineering secondary cell wall deposition in plants
Open Access
- 12 November 2012
- journal article
- Published by Wiley in Plant Biotechnology Journal
- Vol. 11 (3), 325-335
- https://doi.org/10.1111/pbi.12016
Abstract
Lignocellulosic biomass was used for thousands of years as animal feed and is now considered a great sugar source for biofuels production. It is composed mostly of secondary cell walls built with polysaccharide polymers that are embedded in lignin to reinforce the cell wall structure and maintain its integrity. Lignin is the primary material responsible for biomass recalcitrance to enzymatic hydrolysis. During plant development, deep reductions of lignin cause growth defects and often correlate with the loss of vessel integrity that adversely affects water and nutrient transport in plants. The work presented here describes a new approach to decrease lignin content while preventing vessel collapse and introduces a new strategy to boost transcription factor expression in native tissues. We used synthetic biology tools in Arabidopsis to rewire the secondary cell network by changing promoter-coding sequence associations. The result was a reduction in lignin and an increase in polysaccharide depositions in fibre cells. The promoter of a key lignin gene, C4H, was replaced by the vessel-specific promoter of transcription factor VND6. This rewired lignin biosynthesis specifically for vessel formation while disconnecting C4H expression from the fibre regulatory network. Secondly, the promoter of the IRX8 gene, secondary cell wall glycosyltransferase, was used to express a new copy of the fibre transcription factor NST1, and as the IRX8 promoter is induced by NST1, this also created an artificial positive feedback loop (APFL). The combination of strategies-lignin rewiring with APFL insertion-enhances polysaccharide deposition in stems without over-lignifying them, resulting in higher sugar yields after enzymatic hydrolysis.Keywords
This publication has 70 references indexed in Scilit:
- Salicylic acid mediates the reduced growth of lignin down-regulated plantsProceedings of the National Academy of Sciences, 2011
- Dissection of the Transcriptional Program Regulating Secondary Wall Biosynthesis during Wood Formation in PoplarPlant Physiology, 2011
- Tyloses and Phenolic Deposits in Xylem Vessels Impede Water Transport in Low-Lignin Transgenic Poplars: A Study by Cryo-Fluorescence MicroscopyPlant Physiology, 2010
- Convergent Evolution of Syringyl Lignin Biosynthesis via Distinct Pathways in the Lycophyte Selaginella and Flowering PlantsPlant Cell, 2010
- Functional Characterization of Poplar Wood-Associated NAC Domain Transcription FactorsPlant Physiology, 2009
- Functional Analysis of Transcription Factors in ArabidopsisPlant and Cell Physiology, 2009
- Perturbed Lignification Impacts Tree Growth in Hybrid Poplar—A Function of Sink Strength, Vascular Integrity, and Photosynthetic AssimilationPlant Physiology, 2008
- RNAi-mediated suppression of p -coumaroyl-CoA 3′-hydroxylase in hybrid poplar impacts lignin deposition and soluble secondary metabolismProceedings of the National Academy of Sciences, 2008
- Lignin modification improves fermentable sugar yields for biofuel productionNature Biotechnology, 2007
- Use of Dinitrosalicylic Acid Reagent for Determination of Reducing SugarAnalytical Chemistry, 1959