title: PSK-α promotes root growth in Arabidopsis.
abstract: Phytosulfokine-α (PSK-α) is a disulfated pentapeptide described to act as a growth factor in suspension cells. In this study, the involvement of PSK signaling through the PSK receptor gene AtPSKR1 in Arabidopsis root growth was assessed.Expression studies of PSK precursor genes and of AtPSKR1 were performed in roots with RT-PCR and P:GUS analyses. Root elongation, lateral root formation, cell production and root cell elongation were analyzed in wild-type (wt) and in the receptor knockout mutant Atpskr1-T treated with or without synthetic PSK-α.Phytosulfokine and AtPSKR1 genes are differentially expressed in roots. PSK-α induced root growth in a dose-dependent manner without affecting lateral root density. Kinematic analysis established that enhancement of root growth by PSK-α was mainly caused by an increase in cell size. In Atpskr1-T, the primary roots were shorter as a result of reduced mature cell size and a smaller root apical meristem composed of fewer cells than in wt.The results indicate that PSK-α signaling through AtPSKR1 affects root elongation primarily via control of mature cell size. Root organogenesis, on the other hand,is not controlled by PSK-α.
authors.affiliation: Botanisches Institut, Universität Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Kutschmar
authors.affiliation: Botanisches Institut, Universität Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Rzewuski
authors.affiliation: Botanisches Institut, Universität Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Stührwohldt
authors.affiliation: Department of Plant Systems Biology, Flanders Institute of Biotechnology, B-9052 Gent, Belgium.|Department of Molecular Genetics, Gent University, B-9052 Gent, Belgium.|Department of Biology, University of Antwerp, Antwerp, Belgium.
authors.forename: Gerrit T S
authors.initials: GTS
authors.lastname: Beemster
authors.affiliation: Department of Plant Systems Biology, Flanders Institute of Biotechnology, B-9052 Gent, Belgium.|Department of Molecular Genetics, Gent University, B-9052 Gent, Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: Inzé
authors.affiliation: Botanisches Institut, Universität Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany.
authors.forename: Margret
authors.initials: M
authors.lastname: Sauter
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D048429:Cell Size; D018519:Meristem / Q000166:cytology / Q000378:metabolism; D016254:Mutagenesis, Insertional; D036361:Peptide Hormones; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018517:Plant Roots / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D001617:beta-Glucosidase / Q000032:analysis
chemical_list: D029681:Arabidopsis Proteins; C100975:PSK-alpha protein, plant; C515018:PSKR1 protein, Arabidopsis; D036361:Peptide Hormones; D010940:Plant Proteins; D011956:Receptors, Cell Surface; D001617:beta-Glucosidase