Lignin is the main cause of lignocellulosic biomass recalcitrance to industrial enzymatic hydrolysis. By partially replacing the traditional lignin monomers by alternative ones, lignin extractability can be enhanced. To design a lignin that is easier to degrade under alkaline conditions, curcumin (diferuloylmethane) was produced in the model plant Arabidopsis thaliana via simultaneous expression of the turmeric (Curcuma longa) genes DIKETIDE-CoA SYNTHASE (DCS) and CURCUMIN SYNTHASE 2 (CURS2). The transgenic plants produced a plethora of curcumin- and phenylpentanoid-derived compounds with no negative impact on growth. Catalytic hydrogenolysis gave evidence that both curcumin and phenylpentanoids were incorporated into the lignifying cell wall, thereby significantly increasing saccharification efficiency after alkaline pretreatment of the transgenic lines by 14–24% as compared with the wild type. These results demonstrate that non-native monomers can be synthesized and incorporated into the lignin polymer in plants to enhance their biomass processing efficiency.
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P.O. was funded by the National Commission for Scientific and Technological Research (Chile) for a predoctoral fellowship and by SBO-FISH through the ARBOREF project for a postdoctoral fellowship, B.D.M. and L.d.V. were funded by the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT-Vlaanderen) for predoctoral fellowships, F.F. was funded by the Science Without Borders program from CNPq for a postdoctoral fellowship 206329/2014–8, A.P. was funded by the Research Foundation-Flanders (FWO, grant G0C1914N) and Y.T. was funded by Stanford University’s Global Climate and Energy Program (GCEP). S.V.d.B. was funded by PDM KULeuven and by BIOWOOD (FWO-SBO), J.R. was funded by the DOE Great Lakes Bioenergy Research Center (DOE BER Office of Science DE-FC02-07ER64494 and DE-SC0018409) and R.V. was funded by the FWO for a postdoctoral fellowship. The authors thank A. Bleys for help in preparing the manuscript, E. Parthoens (VIB BioImaging Core) for assitance with the fluorescence microscopy and D. Loqué for providing the vector containing pCesA4. The work was also funded by a CLEM grant from I. Lieten to the VIB BioImaging Core for the acquisition of a Zeiss LSM780 microscope.
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Nature Plants (2019)