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Title: Gene stacking of multiple traits for high yield of fermentable sugars in plant biomass

Second-generation biofuels produced from biomass can help to decrease dependency on fossil fuels, bringing about many economic and environmental benefits. To make biomass more suitable for biorefinery use, we need a better understanding of plant cell wall biosynthesis. Increasing the ratio of C6 to C5 sugars in the cell wall and decreasing the lignin content are two important targets in engineering of plants that are more suitable for downstream processing for second-generation biofuel production. Here, we have studied the basic mechanisms of cell wall biosynthesis and identified genes involved in biosynthesis of pectic galactan, including the GALS1 galactan synthase and the UDP-galactose/UDP-rhamnose transporter URGT1. We have engineered plants with a more suitable biomass composition by applying these findings, in conjunction with synthetic biology and gene stacking tools. Plants were engineered to have up to fourfold more pectic galactan in stems by overexpressing GALS1, URGT1, and UGE2, a UDP-glucose epimerase. Furthermore, the increased galactan trait was engineered into plants that were already engineered to have low xylan content by restricting xylan biosynthesis to vessels where this polysaccharide is essential. Finally, the high galactan and low xylan traits were stacked with the low lignin trait obtained by expressing the QsuB gene encodingmore » dehydroshikimate dehydratase in lignifying cells. In conclusion, the results show that approaches to increasing C6 sugar content, decreasing xylan, and reducing lignin content can be combined in an additive manner. Thus, the engineered lines obtained by this trait-stacking approach have substantially improved properties from the perspective of biofuel production, and they do not show any obvious negative growth effects. The approach used in this study can be readily transferred to bioenergy crop plants.« less
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [1] ;  [5] ; ORCiD logo [6]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Joint BioEnergy Inst., Feedstocks Division
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Joint BioEnergy Inst., Feedstocks Division; Ecole Normale Superieure de Cachan, Cachan (France)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Joint BioEnergy Inst., Feedstocks Division; Technical Univ. of Denmark, Lyngby (Denmark)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Joint BioEnergy Inst., Feedstocks Division; Univ. of Copenhagen (Denmark). Dept. of Plant and Environmental Sciences; Univ. of Melbourne (Australia). School of BioSciences
  5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Joint BioEnergy Inst., Feedstocks Division; Univ. Claude Bernard Lyon 1, Villeurbanne (France); Univ. of California, Berkeley, CA (United States). Dept. of Plant and Microbial Biology
  6. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Joint BioEnergy Inst., Feedstocks Division; Univ. of California, Berkeley, CA (United States). Dept. of Plant and Microbial Biology
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Biotechnology for Biofuels
Additional Journal Information:
Journal Volume: 11; Journal Issue: 1; Journal ID: ISSN 1754-6834
Publisher:
BioMed Central
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; 59 BASIC BIOLOGICAL SCIENCES; Plant cell wall; Galactan; Arabidopsis; Pectin; jStack; Xylan; Lignin; Plant engineering
OSTI Identifier:
1425435