title: Salicylic acid modulates levels of phosphoinositide dependent-phospholipase C substrates and products to remodel the Arabidopsis suspension cell transcriptome.
abstract: Basal phosphoinositide-dependent phospholipase C (PI-PLC) activity controls gene expression in Arabidopsis suspension cells and seedlings. PI-PLC catalyzes the production of phosphorylated inositol and diacylglycerol (DAG) from phosphoinositides. It is not known how PI-PLC regulates the transcriptome although the action of DAG-kinase (DGK) on DAG immediately downstream from PI-PLC is responsible for some of the regulation. We previously established a list of genes whose expression is affected in the presence of PI-PLC inhibitors. Here this list of genes was used as a signature in similarity searches of curated plant hormone response transcriptome data. The strongest correlations obtained with the inhibited PI-PLC signature were with salicylic acid (SA) treatments. We confirm here that in Arabidopsis suspension cells SA treatment leads to an increase in phosphoinositides, then demonstrate that SA leads to a significant 20% decrease in phosphatidic acid, indicative of a decrease in PI-PLC products. Previous sets of microarray data were re-assessed. The SA response of one set of genes was dependent on phosphoinositides. Alterations in the levels of a second set of genes, mostly SA-repressed genes, could be related to decreases in PI-PLC products that occur in response to SA action. Together, the two groups of genes comprise at least 40% of all SA-responsive genes. Overall these two groups of genes are distinct in the functional categories of the proteins they encode, their promoter cis-elements and their regulation by DGK or phospholipase D. SA-regulated genes dependent on phosphoinositides are typical SA response genes while those with an SA response that is possibly dependent on PI-PLC products are less SA-specific. We propose a model in which SA inhibits PI-PLC activity and alters levels of PI-PLC products and substrates, thereby regulating gene expression divergently.
authors.affiliation: Université Paris-Est Créteil, Institut d'Ecologie et des Sciences de l'Environnement de Paris Créteil, France ; Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7618, Institut d'Ecologie et des Sciences de l'Environnement de Paris Créteil, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Ruelland
authors.affiliation: Molecular Mechanisms of Plant Cell Regulation, Institute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences Kyiv, Ukraine.
authors.forename: Igor
authors.initials: I
authors.lastname: Pokotylo
authors.affiliation: Université Paris-Est Créteil, Institut d'Ecologie et des Sciences de l'Environnement de Paris Créteil, France ; Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7618, Institut d'Ecologie et des Sciences de l'Environnement de Paris Créteil, France.
authors.forename: Nabila
authors.initials: N
authors.lastname: Djafi
authors.affiliation: Université Paris-Est Créteil, Institut d'Ecologie et des Sciences de l'Environnement de Paris Créteil, France ; Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7618, Institut d'Ecologie et des Sciences de l'Environnement de Paris Créteil, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Cantrel
authors.affiliation: Université Paris-Est Créteil, Institut d'Ecologie et des Sciences de l'Environnement de Paris Créteil, France ; Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7618, Institut d'Ecologie et des Sciences de l'Environnement de Paris Créteil, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Repellin
authors.affiliation: Université Paris-Est Créteil, Institut d'Ecologie et des Sciences de l'Environnement de Paris Créteil, France ; Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7618, Institut d'Ecologie et des Sciences de l'Environnement de Paris Créteil, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Zachowski
keywords: Arabidopsis; diacylglycerol kinase; hormone transduction; lipid signaling; phospholipase C; salicylic acid; trancriptomic