Inactivation of LACCASE8 and LACCASE5 genes in Brachypodium distachyon leads to severe decrease in lignin content and high increase in saccharification yield without impacting plant integrity

Biotechnology for Biofuels

Lacey Samuels¹  Mathias Schuetz¹  Frédéric Legée²  Sébastien Antelme²  Philippe Le Bris²  Clément Barbereau²  Richard Sibout²  Laurent Cézard²  Yin Wang²  Catherine Lapierre²  Marion Dalmais³  Abdelhafid Bendahmane³  Angelina D’Orlando⁴ 

[1] Department of Botany, University of British Columbia;Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay;Institute of Plant Sciences Paris Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université Evry, Université Paris-Saclay;UR1268 BIA (Biopolymères Interactions Assemblages), INRA;

关键词: Laccase;    Oxidation;    Lignin;    Saccharification;    Ferulic acid;    Grass crop;   

DOI  :  10.1186/s13068-019-1525-5

来源: DOAJ

【 摘 要 】

Abstract Background Dedicated lignocellulosic feedstock from grass crops for biofuel production is extensively increasing. However, the access to fermentable cell wall sugars by carbohydrate degrading enzymes is impeded by lignins. These complex polymers are made from reactive oxidized monolignols in the cell wall. Little is known about the laccase-mediated oxidation of monolignols in grasses, and inactivation of the monolignol polymerization mechanism might be a strategy to increase the yield of fermentable sugars. Results LACCASE5 and LACCASE8 are inactivated in a Brachypodium double mutant. Relative to the wild type, the lignin content of extract-free mature culms is decreased by 20–30% and the saccharification yield is increased by 140%. Release of ferulic acid by mild alkaline hydrolysis is also 2.5-fold higher. Interfascicular fibers are mainly affected while integrity of vascular bundles is not impaired. Interestingly, there is no drastic impact of the double mutation on plant growth. Conclusion This work shows that two Brachypodium laccases with clearly identified orthologs in crops are involved in lignification of this model plant. Lignification in interfascicular fibers and metaxylem cells is partly uncoupled in Brachypodium. Orthologs of these laccases are promising targets for improving grass feedstock for cellulosic biofuel production.

【 授权许可】

Unknown