title: Targeted Knockdown of GDCH in Rice Leads to a Photorespiratory-Deficient Phenotype Useful as a Building Block for C4 Rice.
abstract: The glycine decarboxylase complex (GDC) plays a critical role in the photorespiratory C2 cycle of C3 species by recovering carbon following the oxygenation reaction of ribulose-1,5-bisphosphate carboxylase/oxygenase. Loss of GDC from mesophyll cells (MCs) is considered a key early step in the evolution of C4 photosynthesis. To assess the impact of preferentially reducing GDC in rice MCs, we decreased the abundance of OsGDCH (Os10g37180) using an artificial microRNA (amiRNA) driven by a promoter that preferentially drives expression in MCs. GDC H- and P-proteins were undetectable in leaves of gdch lines. Plants exhibited a photorespiratory-deficient phenotype with stunted growth, accelerated leaf senescence, reduced chlorophyll, soluble protein and sugars, and increased glycine accumulation in leaves. Gas exchange measurements indicated an impaired ability to regenerate ribulose 1,5-bisphosphate in photorespiratory conditions. In addition, MCs of gdch lines exhibited a significant reduction in chloroplast area and coverage of the cell wall when grown in air, traits that occur during the later stages of C4 evolution. The presence of these two traits important for C4 photosynthesis and the non-lethal, down-regulation of the photorespiratory C2 cycle positively contribute to efforts to produce a C4 rice prototype.
authors.affiliation: C4 Rice Center, International Rice Research Institute, Los Baños, Philippines These authors contributed equally to this work.
authors.forename: HsiangChun
authors.initials: H
authors.lastname: Lin
authors.affiliation: C4 Rice Center, International Rice Research Institute, Los Baños, Philippines These authors contributed equally to this work.
authors.forename: Shanta
authors.initials: S
authors.lastname: Karki
authors.affiliation: C4 Rice Center, International Rice Research Institute, Los Baños, Philippines These authors contributed equally to this work.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Coe
authors.affiliation: Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, M5S 3B2, Canada.
authors.forename: Shaheen
authors.initials: S
authors.lastname: Bagha
authors.affiliation: Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, M5S 3B2, Canada.
authors.forename: Roxana
authors.initials: R
authors.lastname: Khoshravesh
authors.affiliation: C4 Rice Center, International Rice Research Institute, Los Baños, Philippines.
authors.forename: C Paolo
authors.initials: CP
authors.lastname: Balahadia
authors.affiliation: C4 Rice Center, International Rice Research Institute, Los Baños, Philippines.
authors.forename: Julius
authors.initials: J
authors.lastname: Ver Sagun
authors.affiliation: C4 Rice Center, International Rice Research Institute, Los Baños, Philippines.
authors.forename: Ronald
authors.initials: R
authors.lastname: Tapia
authors.affiliation: C4 Rice Center, International Rice Research Institute, Los Baños, Philippines.
authors.forename: W Krystler
authors.initials: WK
authors.lastname: Israel
authors.affiliation: C4 Rice Center, International Rice Research Institute, Los Baños, Philippines.
authors.forename: Florencia
authors.initials: F
authors.lastname: Montecillo
authors.affiliation: C4 Rice Center, International Rice Research Institute, Los Baños, Philippines.
authors.forename: Albert
authors.initials: A
authors.lastname: de Luna
authors.affiliation: C4 Rice Center, International Rice Research Institute, Los Baños, Philippines.
authors.forename: Florence R
authors.initials: FR
authors.lastname: Danila
authors.affiliation: C4 Rice Center, International Rice Research Institute, Los Baños, Philippines.
authors.forename: Andrea
authors.initials: A
authors.lastname: Lazaro
authors.affiliation: C4 Rice Center, International Rice Research Institute, Los Baños, Philippines.
authors.forename: Czarina M
authors.initials: CM
authors.lastname: Realubit
authors.affiliation: C4 Rice Center, International Rice Research Institute, Los Baños, Philippines.
authors.forename: Michelle G
authors.initials: MG
authors.lastname: Acoba
authors.affiliation: Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, M5S 3B2, Canada.
authors.forename: Tammy L
authors.initials: TL
authors.lastname: Sage
authors.affiliation: ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, Acton, 2601, Australia.
authors.forename: Susanne
authors.initials: S
authors.lastname: von Caemmerer
authors.affiliation: ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, Acton, 2601, Australia.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Furbank
authors.affiliation: School of Biological Sciences, Molecular Plant Sciences, Washington State University, Pullman, WA 99164-4236, USA.
authors.forename: Asaph B
authors.initials: AB
authors.lastname: Cousins
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK.
authors.forename: Julian M
authors.initials: JM
authors.lastname: Hibberd
authors.affiliation: C4 Rice Center, International Rice Research Institute, Los Baños, Philippines Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
authors.forename: W Paul
authors.initials: WP
authors.lastname: Quick
authors.affiliation: Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK sc603@cam.ac.uk.
authors.forename: Sarah
authors.initials: S
authors.lastname: Covshoff
mesh_terms: D057486:Carbon Cycle; D019069:Cell Respiration; D002736:Chloroplasts / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D055785:Gene Knockdown Techniques; D050959:Glycine Decarboxylase Complex / Q000235:genetics / Q000378:metabolism*; D008027:Light; D035683:MicroRNAs / Q000235:genetics; D012275:Oryza / Q000201:enzymology / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D010641:Phenotype; D010788:Photosynthesis; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics / Q000378:metabolism
chemical_list: D035683:MicroRNAs; D010940:Plant Proteins; D050959:Glycine Decarboxylase Complex; D012273:Ribulose-Bisphosphate Carboxylase
keywords: C4 rice; Glycine decarboxylase; Oryza sativa (rice); Photorespiration