Journal Article

Oscillating Aquaporin Phosphorylation and 14-3-3 Proteins Mediate the Circadian Regulation of Leaf Hydraulics

Biochimie et Physiologie Moléculaire des Plantes (BPMP) ; Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), ANR-07-BLAN-0206,LeafFlux,Flux management of water and carbon dioxide in inner leaf tissues. Role of aquaporins and consequences for whole plant hydraulics, Maurel, Christophe, Prado, Karine, Cotelle, Valérie, Bellati, Jorge, Santoni, Veronique, Tang, Ning, Li, Guowei, Tournaire-Roux, Colette, LRSV-Signalisation Calcique et Immunité Végétale (LRSV-SCIV) ; Laboratoire de Recherche en Sciences Végétales (LRSV) ; Université Toulouse III - Paul Sabatier (UT3) ; Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3) ; Université de Toulouse (UT)-U

2019

Overview

The circadian clock regulates plant tissue hydraulics to synchronize water supply with environmental cycles and thereby optimize growth. A role for aquaporin water channels in these processes was suggested by circadian fluctuations in aquaporin transcript abundance. Here, we show that Arabidopsis rosette hydraulic conductivity (Kros) displays a genuine circadian rhythmicity with a peak around midday. Combined immunological and proteomic approaches revealed that phosphorylation at two C-terminal sites (Ser280, Ser283) of Plasma membrane Intrinsic Protein 2;1 (AtPIP2;1), one of major plasma membrane aquaporins in rosettes, shows circadian oscillations and is correlated with Kros. Transgenic expression of phosphodeficient and phosphomimetic forms of this aquaporin indicated AtPIP2;1 phosphorylation to be necessary but not sufficient for Kros regulation. The supporting role of 14-3-3 proteins, known to interact with and regulate phosphorylated proteins, was investigated. Individual knock-out plants for five 14-3-3 protein isoforms expressed in rosettes lacked circadian activation of Kros. Two of these (GRF4 (14-3-3Phi); GRF10 (14-3-3Epsilon)) showed direct interactions with AtPIP2;1 in the plant and upon co-expression in oocytes were able to activate AtPIP2;1, preferentially when the latter is phosphorylated at its two C-terminal sites. We propose that this regulation mechanism assists in activation of phosphorylated AtPIP2;1 during circadian regulation of Kros.

• Publisher: American Society of Plant Biologists (ASPB),CCSD,American Society of Plant Biologists
• Subject: 14-3-3 Proteins - genetics / 14-3-3 Proteins - metabolism / Aquaporins - genetics / Aquaporins - metabolism / Gene Expression Regulation, Plant - genetics / Gene Expression Regulation, Plant - physiology / Life Sciences / Phosphorylation - genetics / Phosphorylation - physiology / Plant Leaves - genetics / Plant Leaves - metabolism / Plants, Genetically Modified - genetics / Plants, Genetically Modified - metabolism / Proteomics - methods / Vegetal Biology
• ISBN: 0004620284000