title: Silencing CHALCONE SYNTHASE in Maize Impedes the Incorporation of Tricin into Lignin and Increases Lignin Content.
abstract: Lignin is a phenolic heteropolymer that is deposited in secondary-thickened cell walls, where it provides mechanical strength. A recent structural characterization of cell walls from monocot species showed that the flavone tricin is part of the native lignin polymer, where it is hypothesized to initiate lignin chains. In this study, we investigated the consequences of altered tricin levels on lignin structure and cell wall recalcitrance by phenolic profiling, nuclear magnetic resonance, and saccharification assays of the naturally silenced maize (Zea mays) C2-Idf (inhibitor diffuse) mutant, defective in the CHALCONE SYNTHASE Colorless2 (C2) gene. We show that the C2-Idf mutant produces highly reduced levels of apigenin- and tricin-related flavonoids, resulting in a strongly reduced incorporation of tricin into the lignin polymer. Moreover, the lignin was enriched in β-β and β-5 units, lending support to the contention that tricin acts to initiate lignin chains and that, in the absence of tricin, more monolignol dimerization reactions occur. In addition, the C2-Idf mutation resulted in strikingly higher Klason lignin levels in the leaves. As a consequence, the leaves of C2-Idf mutants had significantly reduced saccharification efficiencies compared with those of control plants. These findings are instructive for lignin engineering strategies to improve biomass processing and biochemical production.
authors.affiliation: Center for Plant Systems Biology, VIB, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Botany, Institute of Biosciences, University of São Paulo, Butantã, Sao Paulo SP 05508-090, Brazil (I.C.).|Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (W.L., R.A.S., J.R.); and.|Department of Biological System Engineering (W.L., J.R.) and Department of Biochemistry (R.A.S., J.R.), University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: Nubia B
authors.identifier: 0000-0001-8380-5063
authors.initials: NB
authors.lastname: Eloy
authors.affiliation: Center for Plant Systems Biology, VIB, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Botany, Institute of Biosciences, University of São Paulo, Butantã, Sao Paulo SP 05508-090, Brazil (I.C.).|Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (W.L., R.A.S., J.R.); and.|Department of Biological System Engineering (W.L., J.R.) and Department of Biochemistry (R.A.S., J.R.), University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: Wannes
authors.identifier: 0000-0001-9254-1557
authors.initials: W
authors.lastname: Voorend
authors.affiliation: Center for Plant Systems Biology, VIB, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Botany, Institute of Biosciences, University of São Paulo, Butantã, Sao Paulo SP 05508-090, Brazil (I.C.).|Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (W.L., R.A.S., J.R.); and.|Department of Biological System Engineering (W.L., J.R.) and Department of Biochemistry (R.A.S., J.R.), University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: Wu
authors.identifier: 0000-0002-0677-3085
authors.initials: W
authors.lastname: Lan
authors.affiliation: Center for Plant Systems Biology, VIB, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Botany, Institute of Biosciences, University of São Paulo, Butantã, Sao Paulo SP 05508-090, Brazil (I.C.).|Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (W.L., R.A.S., J.R.); and.|Department of Biological System Engineering (W.L., J.R.) and Department of Biochemistry (R.A.S., J.R.), University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: Marina de Lyra Soriano
authors.identifier: 0000-0001-6526-0055
authors.initials: ML
authors.lastname: Saleme
authors.affiliation: Center for Plant Systems Biology, VIB, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Botany, Institute of Biosciences, University of São Paulo, Butantã, Sao Paulo SP 05508-090, Brazil (I.C.).|Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (W.L., R.A.S., J.R.); and.|Department of Biological System Engineering (W.L., J.R.) and Department of Biochemistry (R.A.S., J.R.), University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: Igor
authors.identifier: 0000-0002-6789-2432
authors.initials: I
authors.lastname: Cesarino
authors.affiliation: Center for Plant Systems Biology, VIB, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Botany, Institute of Biosciences, University of São Paulo, Butantã, Sao Paulo SP 05508-090, Brazil (I.C.).|Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (W.L., R.A.S., J.R.); and.|Department of Biological System Engineering (W.L., J.R.) and Department of Biochemistry (R.A.S., J.R.), University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: Ruben
authors.identifier: 0000-0001-5848-3138
authors.initials: R
authors.lastname: Vanholme
authors.affiliation: Center for Plant Systems Biology, VIB, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Botany, Institute of Biosciences, University of São Paulo, Butantã, Sao Paulo SP 05508-090, Brazil (I.C.).|Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (W.L., R.A.S., J.R.); and.|Department of Biological System Engineering (W.L., J.R.) and Department of Biochemistry (R.A.S., J.R.), University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: Rebecca A
authors.identifier: 0000-0003-2363-2820
authors.initials: RA
authors.lastname: Smith
authors.affiliation: Center for Plant Systems Biology, VIB, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Botany, Institute of Biosciences, University of São Paulo, Butantã, Sao Paulo SP 05508-090, Brazil (I.C.).|Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (W.L., R.A.S., J.R.); and.|Department of Biological System Engineering (W.L., J.R.) and Department of Biochemistry (R.A.S., J.R.), University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: Geert
authors.identifier: 0000-0002-0337-2999
authors.initials: G
authors.lastname: Goeminne
authors.affiliation: Center for Plant Systems Biology, VIB, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Botany, Institute of Biosciences, University of São Paulo, Butantã, Sao Paulo SP 05508-090, Brazil (I.C.).|Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (W.L., R.A.S., J.R.); and.|Department of Biological System Engineering (W.L., J.R.) and Department of Biochemistry (R.A.S., J.R.), University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: Andreas
authors.identifier: 0000-0001-7680-912X
authors.initials: A
authors.lastname: Pallidis
authors.affiliation: Center for Plant Systems Biology, VIB, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Botany, Institute of Biosciences, University of São Paulo, Butantã, Sao Paulo SP 05508-090, Brazil (I.C.).|Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (W.L., R.A.S., J.R.); and.|Department of Biological System Engineering (W.L., J.R.) and Department of Biochemistry (R.A.S., J.R.), University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: Kris
authors.identifier: 0000-0002-3121-9705
authors.initials: K
authors.lastname: Morreel
authors.affiliation: Center for Plant Systems Biology, VIB, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Botany, Institute of Biosciences, University of São Paulo, Butantã, Sao Paulo SP 05508-090, Brazil (I.C.).|Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (W.L., R.A.S., J.R.); and.|Department of Biological System Engineering (W.L., J.R.) and Department of Biochemistry (R.A.S., J.R.), University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: José
authors.identifier: 0000-0003-0591-7021
authors.initials: J
authors.lastname: Nicomedes
authors.affiliation: Center for Plant Systems Biology, VIB, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.).|Department of Botany, Institute of Biosciences, University of São Paulo, Butantã, Sao Paulo SP 05508-090, Brazil (I.C.).|Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (W.L., R.A.S., J.R.); and.|Department of Biological System Engineering (W.L., J.R.) and Department of Biochemistry (R.A.S., J.R.), University of Wisconsin, Madison, Wisconsin 53706.
authors.forename: John
authors.identifier: 0000-0002-6093-4521
authors.initials: J
authors.lastname: Ralph
authors.affiliation: Center for Plant Systems Biology, VIB, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.); wout.boerjan@psb.vib-ugent.be.|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium (N.B.E., W.V., M.d.L.S.S., I.C., R.V., G.G., A.P., K.M., J.N., W.B.); wout.boerjan@psb.vib-ugent.be.|Department of Botany, Institute of Biosciences, University of São Paulo, Butantã, Sao Paulo SP 05508-090, Brazil (I.C.); wout.boerjan@psb.vib-ugent.be.|Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (W.L., R.A.S., J.R.); and wout.boerjan@psb.vib-ugent.be.|Department of Biological System Engineering (W.L., J.R.) and Department of Biochemistry (R.A.S., J.R.), University of Wisconsin, Madison, Wisconsin 53706 wout.boerjan@psb.vib-ugent.be.
authors.forename: Wout
authors.identifier: 0000-0003-1495-510X
authors.initials: W
authors.lastname: Boerjan
mesh_terms: D000217:Acyltransferases / Q000235:genetics* / Q000378:metabolism; D018533:Biomass; D002473:Cell Wall / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics; D005419:Flavonoids / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D008031:Lignin / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D053858:Metabolic Networks and Pathways / Q000235:genetics; D009154:Mutation / Q000235:genetics; D010636:Phenols / Q000378:metabolism; D010641:Phenotype; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism; D018547:Plant Stems / Q000254:growth & development / Q000378:metabolism; D003313:Zea mays / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development
chemical_list: D005419:Flavonoids; D010636:Phenols; D008031:Lignin; C017769:tricin; D000217:Acyltransferases; C020141:flavanone synthetase