Engineering Curcumin Biosynthesis in Poplar Affects Lignification and Biomass Yield
Barbara De Meester1,2, Paula Oyarce1,2, Ruben Vanholme1,2
1Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.
Frontiers in Plant Science
|July 21, 2022
Summary
Engineering poplar plants to produce curcumin did not improve biomass deconstruction for bioenergy. While the approach enhanced lignin modification, it resulted in negative growth impacts and no increase in sugar yield after pretreatment.
Area of Science:
- Plant Biotechnology
- Biomass Engineering
- Bioenergy Crops
Background:
- Lignocellulosic biomass recalcitrance hinders efficient biofuel production.
- Engineering lignin biosynthesis pathways offers a strategy to improve biomass deconstruction.
- Previous success in Arabidopsis using curcumin incorporation showed promise for enhanced saccharification.
Purpose of the Study:
- To translate the strategy of incorporating the alternative lignin monomer curcumin into the bio-energy crop poplar.
- To assess the impact of curcumin incorporation on poplar growth, wood composition, and saccharification efficiency.
Main Methods:
- Heterologous expression of DIKETIDE-CoA SYNTHASE (DCS) and CURCUMIN SYNTHASE2 (CURS2) in poplar under the CELLULOSE SYNTHASE A8-B promoter (ProCesA8-B).
- Analysis of growth phenotype, wood composition (cellulose, polysaccharides, lignin content and structure), and saccharification efficiency after various pretreatments.
Main Results:
- Transgenic poplars expressing ProCesA8-B:DCS_CURS2 exhibited shoot-tip necrosis and yield penalties.
- Wood composition was altered: 21% less cellulose, 28% more matrix polysaccharides, 23% more lignin, with modified lignin structure (reduced S/G ratio, increased H units, decreased p-hydroxybenzoates, increased phenylcoumaran units).
- Saccharification efficiency was not improved compared to wild-type, regardless of pretreatment.
Conclusions:
- Translating genetic engineering strategies across plant species is crucial for assessing real-world applicability.
- The ProCesA8-B promoter-driven curcumin incorporation strategy in poplar negatively impacted growth and did not enhance biomass saccharification.
- Further research requires fine-tuning of promoters and potentially exploring other crops or alternative strategies for improved bioenergy feedstock.
