Engineering secondary cell wall deposition in plants. Issue 3 (12th November 2012)

• Record Type: Journal Article
• Authors: Yang, Fan; Mitra, Prajakta; Zhang, Ling; Prak, Lina; Verhertbruggen, Yves; Kim, Jin‐Sun; Sun, Lan; Zheng, Kejian; Tang, Kexuan; Auer, Manfred; Scheller, Henrik V.; Loqué, Dominique
• Is Part Of: Plant biotechnology journal. Volume 11:Issue 3(2013:Apr.)
• Page Start: 325
• Page End: 335
• Publication Date: 2012-11-12
• Subjects: Plant biotechnology -- Periodicals; Plant genetic engineering -- Periodicals; 630.272
• DOI: 10.1111/pbi.12016
• Languages: English
• ISSNs: 1467-7644

Abstract

<abstract abstract-type="main" xml:lang="en" id="pbi12016-abs-0001"> <title>Summary</title> <p>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 <italic>Arabidopsis</italic> 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, <italic>C4H, </italic> was replaced by the vessel‐specific promoter of transcription factor <italic>VND6</italic>. This rewired lignin biosynthesis specifically for vessel formation while disconnecting <italic>C4H</italic> expression from the fibre regulatory network. Secondly, the promoter of the <italic>IRX8</italic> gene, secondary cell wall glycosyltransferase, was used to express a new copy of the fibre transcription factor <italic>NST1</italic>, and as the <italic>IRX8</italic> promoter is induced by <italic>NST1</italic>, 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.</p> </abstract>