title: Mutation of the inducible ARABIDOPSIS THALIANA CYTOCHROME P450 REDUCTASE2 alters lignin composition and improves saccharification.
abstract: ARABIDOPSIS THALIANA CYTOCHROME P450 REDUCTASE1 (ATR1) and ATR2 provide electrons from NADPH to a large number of CYTOCHROME P450 (CYP450) enzymes in Arabidopsis (Arabidopsis thaliana). Whereas ATR1 is constitutively expressed, the expression of ATR2 appears to be induced during lignin biosynthesis and upon stresses. Therefore, ATR2 was hypothesized to be preferentially involved in providing electrons to the three CYP450s involved in lignin biosynthesis: CINNAMATE 4-HYDROXYLASE (C4H), p-COUMARATE 3-HYDROXYLASE1 (C3H1), and FERULATE 5-HYDROXYLASE1 (F5H1). Here, we show that the atr2 mutation resulted in a 6% reduction in total lignin amount in the main inflorescence stem and a compositional shift of the remaining lignin to a 10-fold higher fraction of p-hydroxyphenyl units at the expense of syringyl units. Phenolic profiling revealed shifts in lignin-related phenolic metabolites, in particular with the substrates of C4H, C3H1 and F5H1 accumulating in atr2 mutants. Glucosinolate and flavonol glycoside biosynthesis, both of which also rely on CYP450 activities, appeared less affected. The cellulose in the atr2 inflorescence stems was more susceptible to enzymatic hydrolysis after alkaline pretreatment, making ATR2 a potential target for engineering plant cell walls for biofuel production.
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium (L.S., R.V., J.G., G.G., R.H., W.B.);Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium (L.S., R.V., J.G., G.G., R.H., W.B.); andDepartments of Biochemistry and Biological Systems Engineering and Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (H.K., J.R.).
authors.forename: Lisa
authors.initials: L
authors.lastname: Sundin
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium (L.S., R.V., J.G., G.G., R.H., W.B.);Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium (L.S., R.V., J.G., G.G., R.H., W.B.); andDepartments of Biochemistry and Biological Systems Engineering and Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (H.K., J.R.).
authors.forename: Ruben
authors.initials: R
authors.lastname: Vanholme
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium (L.S., R.V., J.G., G.G., R.H., W.B.);Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium (L.S., R.V., J.G., G.G., R.H., W.B.); andDepartments of Biochemistry and Biological Systems Engineering and Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (H.K., J.R.).
authors.forename: Jan
authors.initials: J
authors.lastname: Geerinck
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium (L.S., R.V., J.G., G.G., R.H., W.B.);Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium (L.S., R.V., J.G., G.G., R.H., W.B.); andDepartments of Biochemistry and Biological Systems Engineering and Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (H.K., J.R.).
authors.forename: Geert
authors.initials: G
authors.lastname: Goeminne
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium (L.S., R.V., J.G., G.G., R.H., W.B.);Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium (L.S., R.V., J.G., G.G., R.H., W.B.); andDepartments of Biochemistry and Biological Systems Engineering and Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (H.K., J.R.).
authors.forename: René
authors.initials: R
authors.lastname: Höfer
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium (L.S., R.V., J.G., G.G., R.H., W.B.);Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium (L.S., R.V., J.G., G.G., R.H., W.B.); andDepartments of Biochemistry and Biological Systems Engineering and Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (H.K., J.R.).
authors.forename: Hoon
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium (L.S., R.V., J.G., G.G., R.H., W.B.);Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium (L.S., R.V., J.G., G.G., R.H., W.B.); andDepartments of Biochemistry and Biological Systems Engineering and Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (H.K., J.R.).
authors.forename: John
authors.initials: J
authors.lastname: Ralph
authors.affiliation: Department of Plant Systems Biology, VIB, 9052 Ghent, Belgium (L.S., R.V., J.G., G.G., R.H., W.B.);Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium (L.S., R.V., J.G., G.G., R.H., W.B.); andDepartments of Biochemistry and Biological Systems Engineering and Department of Energy Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin 53726 (H.K., J.R.) woboe@psb.vib-ugent.be.
authors.forename: Wout
authors.initials: W
authors.lastname: Boerjan
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism; D004583:Electrons; D044948:Flavonols / Q000378:metabolism; D005961:Glucosinolates / Q000378:metabolism; D006868:Hydrolysis; D056626:Inflorescence / Q000201:enzymology / Q000235:genetics; D008031:Lignin / Q000378:metabolism*; D009154:Mutation; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010636:Phenols / Q000378:metabolism; D018547:Plant Stems / Q000201:enzymology / Q000235:genetics; D020598:Proto-Oncogene Proteins c-myb / Q000235:genetics / Q000378:metabolism; D064210:Secondary Metabolism
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D002482:Cellulose; D044948:Flavonols; D005961:Glucosinolates; D008031:Lignin; D009249:NADP; D010636:Phenols; D020598:Proto-Oncogene Proteins c-myb; C511988:ATR1 protein, Arabidopsis; C471575:ATR2 protein, Arabidopsis