title: CCR1, an enzyme required for lignin biosynthesis in Arabidopsis, mediates cell proliferation exit for leaf development.
abstract: After initiation, leaves first undergo rapid cell proliferation. During subsequent development, leaf cells gradually exit the proliferation phase and enter the expansion stage, following a basipetally ordered pattern starting at the leaf tip. The molecular mechanism directing this pattern of leaf development is as yet poorly understood. By genetic screening and characterization of Arabidopsis mutants defective in exit from cell proliferation, we show that the product of the CINNAMOYL CoA REDUCTASE (CCR1) gene, which is required for lignin biosynthesis, participates in the process of cell proliferation exit in leaves. CCR1 is expressed basipetally in the leaf, and ccr1 mutants exhibited multiple abnormalities, including increased cell proliferation. The ccr1 phenotypes are not due to the reduced lignin content, but instead are due to the dramatically increased level of ferulic acid (FeA), an intermediate in lignin biosynthesis. FeA is known to have antioxidant activity, and the levels of reactive oxygen species (ROS) in ccr1 were markedly reduced. We also characterized another double mutant in CAFFEIC ACID O-METHYLTRANSFERASE (comt) and CAFFEOYL CoA 3-O-METHYLTRANSFERASE (ccoaomt), in which the FeA level was dramatically reduced. Cell proliferation in comt ccoaomt leaves was decreased, accompanied by elevated ROS levels, and the mutant phenotypes were partially rescued by treatment with FeA or another antioxidant (N-acetyl-L-cysteine). Taken together, our results suggest that CCR1, FeA and ROS coordinate cell proliferation exit in normal leaf development.
authors.affiliation: National Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China.
authors.forename: Jingshi
authors.initials: J
authors.lastname: Xue
authors.affiliation: National Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China.
authors.forename: Dexian
authors.initials: D
authors.lastname: Luo
authors.affiliation: National Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China.
authors.forename: Deyang
authors.initials: D
authors.lastname: Xu
authors.affiliation: National Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China.
authors.forename: Minhuan
authors.initials: M
authors.lastname: Zeng
authors.affiliation: National Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Cui
authors.affiliation: National Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China.
authors.forename: Laigeng
authors.initials: L
authors.lastname: Li
authors.affiliation: National Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China.
authors.forename: Hai
authors.initials: H
authors.lastname: Huang
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism*; D008031:Lignin / Q000096:biosynthesis*; D018515:Plant Leaves / Q000254:growth & development; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D017382:Reactive Oxygen Species; D008031:Lignin; D011495:Histone-Lysine N-Methyltransferase; C556085:LAZ2 protein, Arabidopsis
keywords: Arabidopsis; antioxidant activity; cell proliferation exit; cinnamoyl CoA reductase 1; ferulic acid; reactive oxygen species