ROTUNDA3 function in plant development by phosphatase 2A-mediated regulation of auxin transporter recycling Journal Article

Author(s): Karampelias, Michael; Neyt, Pia; De Groeve, Steven; Aesaert, Stijn; Coussens, Griet; Rolčík, Jakub; Bruno, Leonardo; De Winne, Nancy; Van Minnebruggen, Annemie; Van Montagu, Marc C; Ponce, Maria R; Micol, José L; Friml, Jiří; De Jaeger, Geert D; Van Lijsebettens, Mieke
Article Title: ROTUNDA3 function in plant development by phosphatase 2A-mediated regulation of auxin transporter recycling
Affiliation IST Austria
Abstract: The shaping of organs in plants depends on the intercellular flow of the phytohormone auxin, of which the directional signaling is determined by the polar subcellular localization of PIN-FORMED (PIN) auxin transport proteins. Phosphorylation dynamics of PIN proteins are affected by the protein phosphatase 2A (PP2A) and the PINOID kinase, which act antagonistically to mediate their apical-basal polar delivery. Here, we identified the ROTUNDA3 (RON3) protein as a regulator of the PP2A phosphatase activity in Arabidopsis thaliana. The RON3 gene was map-based cloned starting from the ron3-1 leaf mutant and found to be a unique, plant-specific gene coding for a protein with high and dispersed proline content. The ron3-1 and ron3-2 mutant phenotypes [i.e., reduced apical dominance, primary root length, lateral root emergence, and growth; increased ectopic stages II, IV, and V lateral root primordia; decreased auxin maxima in indole-3-acetic acid (IAA)-treated root apical meristems; hypergravitropic root growth and response; increased IAA levels in shoot apices; and reduced auxin accumulation in root meristems] support a role for RON3 in auxin biology. The affinity-purified PP2A complex with RON3 as bait suggested that RON3 might act in PIN transporter trafficking. Indeed, pharmacological interference with vesicle trafficking processes revealed that single ron3-2 and double ron3-2 rcn1 mutants have altered PIN polarity and endocytosis in specific cells. Our data indicate that RON3 contributes to auxin-mediated development by playing a role in PIN recycling and polarity establishment through regulation of the PP2A complex activity.
Keywords: PP2A; Plant development; Auxin; Arabidopsis PIN recycling
Journal Title: PNAS
Volume: 113
Issue 10
ISSN: 1091-6490
Publisher: National Academy of Sciences  
Date Published: 2016-03-08
Start Page: 2768
End Page: 2773
DOI: 10.1073/pnas.1501343112
Notes: This work was supported by the Ghent University Special Research Fund (M.K.), the European Research Council (Project ERC- 2011-StG-20101109-PSDP) (to J.F.), and the Körber European Science Foun- dation (J.F.). S.D.G. is indebted to the Agency for Science and Technology for a predoctoral fellowship.
Open access: yes (repository)