title: Starch Synthase 4 and Plastidal Phosphorylase Differentially Affect Starch Granule Number and Morphology.
abstract: The process of starch granule formation in leaves of Arabidopsis (Arabidopsis thaliana) is obscure. Besides STARCH SYNTHASE4 (SS4), the PLASTIDIAL PHOSPHORYLASE (PHS1) also seems to be involved, sincedpe2-1/phs1adouble mutants lacking both PHS1 and the cytosolic DISPROPORTIONATING ENZYME2 (DPE2) displayed only one starch granule per chloroplast under normal growth conditions. For further studies, adpe2-1/phs1a/ss4triple mutant and various combinations of double mutants were generated and metabolically analyzed with a focus on starch metabolism. Thedpe2-1/phs1a/ss4mutant revealed a massive starch excess phenotype. Furthermore, these plants grown under 12 h of light/12 h of dark harbored a single large and spherical starch granule per plastid. The number of starch granules was constant when the light/dark regime was altered, but this was not observed in the parental lines. With regard to growth, photosynthetic parameters, and metabolic analyses, the triple mutant additionally displayed alterations in comparison withss4anddpe2-1/phs1aThe results clearly illustrate that PHS1 and SS4 are differently involved in starch granule formation and do not act in series. However, SS4 appears to exert a stronger influence. In connection with the characterized double mutants, we discuss the generation of starch granules and the observed formation of spherical starch granules.
authors.affiliation: Biopolymer Analytics (I.M., J.F.) and Zoophysiology (O.B.), Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam-Golm, Germany; and.|Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany (S.A., R.F., A.R.F., M.A.S., J.E.L.).
authors.forename: Irina
authors.initials: I
authors.lastname: Malinova
authors.affiliation: Biopolymer Analytics (I.M., J.F.) and Zoophysiology (O.B.), Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam-Golm, Germany; and.|Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany (S.A., R.F., A.R.F., M.A.S., J.E.L.).
authors.forename: Saleh
authors.initials: S
authors.lastname: Alseekh
authors.affiliation: Biopolymer Analytics (I.M., J.F.) and Zoophysiology (O.B.), Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam-Golm, Germany; and.|Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany (S.A., R.F., A.R.F., M.A.S., J.E.L.).
authors.forename: Regina
authors.identifier: http://orcid.org/0000-0002-9936-1337
authors.initials: R
authors.lastname: Feil
authors.affiliation: Biopolymer Analytics (I.M., J.F.) and Zoophysiology (O.B.), Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam-Golm, Germany; and.|Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany (S.A., R.F., A.R.F., M.A.S., J.E.L.).
authors.forename: Alisdair R
authors.initials: AR
authors.lastname: Fernie
authors.affiliation: Biopolymer Analytics (I.M., J.F.) and Zoophysiology (O.B.), Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam-Golm, Germany; and.|Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany (S.A., R.F., A.R.F., M.A.S., J.E.L.).
authors.forename: Otto
authors.initials: O
authors.lastname: Baumann
authors.affiliation: Biopolymer Analytics (I.M., J.F.) and Zoophysiology (O.B.), Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam-Golm, Germany; and.|Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany (S.A., R.F., A.R.F., M.A.S., J.E.L.).
authors.forename: Mark Aurel
authors.initials: MA
authors.lastname: Schöttler
authors.affiliation: Biopolymer Analytics (I.M., J.F.) and Zoophysiology (O.B.), Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam-Golm, Germany; and.|Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany (S.A., R.F., A.R.F., M.A.S., J.E.L.).
authors.forename: John E
authors.identifier: http://orcid.org/0000-0001-8533-3004
authors.initials: JE
authors.lastname: Lunn
authors.affiliation: Biopolymer Analytics (I.M., J.F.) and Zoophysiology (O.B.), Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam-Golm, Germany; and fettke@uni-potsdam.de.|Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany (S.A., R.F., A.R.F., M.A.S., J.E.L.) fettke@uni-potsdam.de.
authors.forename: Joerg
authors.identifier: http://orcid.org/0000-0003-0137-7611
authors.initials: J
authors.lastname: Fettke
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D006004:Glycogen Debranching Enzyme System / Q000235:genetics / Q000378:metabolism; D008027:Light; D008854:Microscopy, Electron; D009154:Mutation; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D018087:Plastids / Q000201:enzymology*; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D013213:Starch / Q000378:metabolism* / Q000648:ultrastructure; D013214:Starch Synthase / Q000235:genetics* / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C000592241:DPE2 protein, Arabidopsis; D006004:Glycogen Debranching Enzyme System; D013213:Starch; D013214:Starch Synthase; C520418:starch synthase IV, Arabidopsis; C514675:PHS1 protein, Arabidopsis; D017027:Protein Tyrosine Phosphatases