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Downregulation of RWA genes in hybrid aspen affects xylan acetylation and wood saccharification
Author(s) -
Pawar Prashant MohanAnupama,
Ratke Christine,
Balasubramanian Vimal K.,
Chong SunLi,
Gandla Madhavi Latha,
Adriasola Mathilda,
Sparrman Tobias,
Hedenström Mattias,
Szwaj Klaudia,
DerbaMaceluch Marta,
Gaertner Cyril,
Mouille Gregory,
Ezcurra Ines,
Tenkanen Maija,
Jönsson Leif J.,
Mellerowicz Ewa J.
Publication year - 2017
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.14489
Subject(s) - xylose , xylan , hydrolysis , xyloglucan , chemistry , acetylation , biochemistry , glycoside hydrolase , hardwood , fermentation , cell wall , botany , biology , gene
Summary High acetylation of angiosperm wood hinders its conversion to sugars by glycoside hydrolases, subsequent ethanol fermentation and (hence) its use for biofuel production. We studied the REDUCED WALL ACETYLATION ( RWA ) gene family of the hardwood model Populus to evaluate its potential for improving saccharification. The family has two clades, AB and CD , containing two genes each. All four genes are expressed in developing wood but only RWA ‐A and ‐B are activated by master switches of the secondary cell wall Pt NST 1 and Pt MYB 21. Histochemical analysis of promoter:: GUS lines in hybrid aspen ( Populus tremula × tremuloides ) showed activation of RWA ‐A and ‐B promoters in the secondary wall formation zone, while RWA ‐C and ‐D promoter activity was diffuse. Ectopic downregulation of either clade reduced wood xylan and xyloglucan acetylation. Suppressing both clades simultaneously using the wood‐specific promoter reduced wood acetylation by 25% and decreased acetylation at position 2 of Xyl p in the dimethyl sulfoxide ‐extracted xylan. This did not affect plant growth but decreased xylose and increased glucose contents in the noncellulosic monosaccharide fraction, and increased glucose and xylose yields of wood enzymatic hydrolysis without pretreatment. Both RWA clades regulate wood xylan acetylation in aspen and are promising targets to improve wood saccharification.