In order to create trees in which cellulose, the most abundant component in biomass, can be enzymatically hydrolyzed highly for the production of bioethanol, we examined the saccharification of xylem from several transgenic poplars, each overexpressing either xyloglucanase, cellulase, xylanase, or galactanase. The level of cellulose degradation achieved by a cellulase preparation was markedly greater in the xylem overexpressing xyloglucanase and much greater in the xylems overexpressing xylanase and cellulase than in the xylem of the wild-type plant. Although a high degree of degradation occurred in all xylems at all loci, the crystalline region of the cellulose microfibrils was highly degraded in the xylem overexpressing xyloglucanase. Since the complex between microfibrils and xyloglucans could be one region that is particularly resistant to cellulose degradation, loosening xyloglucan could facilitate the enzymatic hydrolysis of cellulose in wood.
Bibliographical noteFunding Information:
Funding for this work was provided by the Program for the Promotion of Basic Research Activities for Innovative Biosciences (PROBRAIN) and by JSPS KAKENHI (grant nos 19208016 and 19405030). This work is also part of the outcome of the JSPS Global COE Program (E-04): In Search of Sustainable Humanosphere in Asia and Africa. No conflict of interest declared.
- Overexpression of xyloglucanase
- Transgenic poplar