title: Pectin Methylesterification Impacts the Relationship between Photosynthesis and Plant Growth.
abstract: Photosynthesis occurs in mesophyll cells of specialized organs such as leaves. The rigid cell wall encapsulating photosynthetic cells controls the expansion and distribution of cells within photosynthetic tissues. The relationship between photosynthesis and plant growth is affected by leaf area. However, the underlying genetic mechanisms affecting carbon partitioning to different aspects of leaf growth are not known. To fill this gap, we analyzed Arabidopsis plants with altered levels of pectin methylesterification, which is known to modulate cell wall plasticity and plant growth. Pectin methylesterification levels were varied through manipulation of cotton Golgi-related (CGR) 2 or 3 genes encoding two functionally redundant pectin methyltransferases. Increased levels of methylesterification in a line over-expressing CGR2 (CGR2OX) resulted in highly expanded leaves with enhanced intercellular air spaces; reduced methylesterification in a mutant lacking both CGR-genes 2 and 3 (cgr2/3) resulted in thin but dense leaf mesophyll that limited CO2 diffusion to chloroplasts. Leaf, root, and plant dry weight were enhanced in CGR2OX but decreased in cgr2/3. Differences in growth between wild type and the CGR-mutants can be explained by carbon partitioning but not by variations in area-based photosynthesis. Therefore, photosynthesis drives growth through alterations in carbon partitioning to new leaf area growth and leaf mass per unit leaf area; however, CGR-mediated pectin methylesterification acts as a primary factor in this relationship through modulation of the expansion and positioning of the cells in leaves, which in turn drive carbon partitioning by generating dynamic carbon demands in leaf area growth and leaf mass per unit leaf area.
authors.affiliation: Department of Biochemistry and Molecular Biology (S.M.W., F.C.A., T.D.S.); Department of Energy Plant Research Laboratory (S.-J.K., L.R., F.B.); Department of Energy Great Lakes Bioenergy Research Center (S.-J.K., F.B.); and Department of Plant Biology (F.B.), Michigan State University, East Lansing, Michigan 48824.
authors.forename: Sarathi
authors.identifier: 0000-0002-0591-4210
authors.initials: S
authors.lastname: M Weraduwage
authors.affiliation: Department of Biochemistry and Molecular Biology (S.M.W., F.C.A., T.D.S.); Department of Energy Plant Research Laboratory (S.-J.K., L.R., F.B.); Department of Energy Great Lakes Bioenergy Research Center (S.-J.K., F.B.); and Department of Plant Biology (F.B.), Michigan State University, East Lansing, Michigan 48824.
authors.forename: Sang-Jin
authors.initials: SJ
authors.lastname: Kim
authors.affiliation: Department of Biochemistry and Molecular Biology (S.M.W., F.C.A., T.D.S.); Department of Energy Plant Research Laboratory (S.-J.K., L.R., F.B.); Department of Energy Great Lakes Bioenergy Research Center (S.-J.K., F.B.); and Department of Plant Biology (F.B.), Michigan State University, East Lansing, Michigan 48824.
authors.forename: Luciana
authors.initials: L
authors.lastname: Renna
authors.affiliation: Department of Biochemistry and Molecular Biology (S.M.W., F.C.A., T.D.S.); Department of Energy Plant Research Laboratory (S.-J.K., L.R., F.B.); Department of Energy Great Lakes Bioenergy Research Center (S.-J.K., F.B.); and Department of Plant Biology (F.B.), Michigan State University, East Lansing, Michigan 48824 tsharkey@msu.edu fb@msu.edu.
authors.forename: Fransisca
authors.initials: F
authors.lastname: C Anozie
authors.affiliation: Department of Biochemistry and Molecular Biology (S.M.W., F.C.A., T.D.S.); Department of Energy Plant Research Laboratory (S.-J.K., L.R., F.B.); Department of Energy Great Lakes Bioenergy Research Center (S.-J.K., F.B.); and Department of Plant Biology (F.B.), Michigan State University, East Lansing, Michigan 48824 tsharkey@msu.edu fb@msu.edu.
authors.forename: Thomas
authors.identifier: 0000-0002-4423-3223
authors.initials: T
authors.lastname: D Sharkey
authors.affiliation: Department of Biochemistry and Molecular Biology (S.M.W., F.C.A., T.D.S.); Department of Energy Plant Research Laboratory (S.-J.K., L.R., F.B.); Department of Energy Great Lakes Bioenergy Research Center (S.-J.K., F.B.); and Department of Plant Biology (F.B.), Michigan State University, East Lansing, Michigan 48824 tsharkey@msu.edu fb@msu.edu.
authors.forename: Federica
authors.initials: F
authors.lastname: Brandizzi
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D004951:Esterification; D058503:Mesophyll Cells / Q000378:metabolism; D008745:Methylation; D010368:Pectins / Q000378:metabolism*; D010788:Photosynthesis; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; C569456:CGR3 protein, Arabidopsis; D002245:Carbon Dioxide; D002244:Carbon; D010368:Pectins