Sugar release and growth of biofuel crops are improved by downregulation of pectin biosynthesis

Ajaya K. Biswal, Melani A. Atmodjo, Mi Li, Holly L. Baxter, Chang Geun Yoo, Yunqiao Pu, Yi Ching Lee, Mitra Mazarei, Ian M. Black, Ji Yi Zhang, Hema Ramanna, Adam L. Bray, Zachary R. King, Peter R. Lafayette, Sivakumar Pattathil, Bryon S. Donohoe, Sushree S. Mohanty, David Ryno, Kelsey Yee, Olivia A. ThompsonMiguel Rodriguez, Alexandru Dumitrache, Jace Natzke, Kim Winkeler, Cassandra Collins, Xiaohan Yang, Li Tan, Robert W. Sykes, Erica L. Gjersing, Angela Ziebell, Geoffrey B. Turner, Stephen R. Decker, Michael G. Hahn, Brian H. Davison, Michael K. Udvardi, Jonathan R. Mielenz, Mark F. Davis, Richard S. Nelson, Wayne A. Parrott, Arthur J. Ragauskas, C. Neal Stewart, Debra Mohnen

Research output: Contribution to journalArticleResearchpeer-review

47 Citations (Scopus)

Abstract

Cell walls in crops and trees have been engineered for production of biofuels and commodity chemicals, but engineered varieties often fail multi-year field trials and are not commercialized. We engineered reduced expression of a pectin biosynthesis gene (Galacturonosyltransferase 4, GAUT4) in switchgrass and poplar, and find that this improves biomass yields and sugar release from biomass processing. Both traits were maintained in a 3-year field trial of GAUT4-knockdown switchgrass, with up to sevenfold increased saccharification and ethanol production and sixfold increased biomass yield compared with control plants. We show that GAUT4 is an α-1,4-galacturonosyltransferase that synthesizes homogalacturonan (HG). Downregulation of GAUT4 reduces HG and rhamnogalacturonan II (RGII), reduces wall calcium and boron, and increases extractability of cell wall sugars. Decreased recalcitrance in biomass processing and increased growth are likely due to reduced HG and RGII cross-linking in the cell wall.

Original languageEnglish
Pages (from-to)249-257
Number of pages9
JournalNature Biotechnology
Volume36
Issue number3
DOIs
Publication statusPublished - 1 Mar 2018
Externally publishedYes

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