Phospholipase D activation is an early component of the salicylic acid signaling pathway in Arabidopsis cell suspensions.
Salicylic acid (SA) plays a central role in defense against pathogen attack, as well as in germination, flowering, senescence, and the acquisition of thermotolerance. In this report we investigate the involvement of phospholipase D (PLD) in the SA signaling pathway. In presence of exogenous primary alcohols, the production of phosphatidic acid by PLD is diverted toward the formation of phosphatidylalcohols through a reaction called transphosphatidylation. By in vivo metabolic phospholipid labeling with (33)P(i), PLD activity was found to be induced 45 min after addition of SA. We show that incubation of Arabidopsis (Arabidopsis thaliana) cell suspensions with primary alcohols inhibited the induction of two SA-responsive genes, PATHOGENESIS-RELATED1 and WRKY38, in a dose-dependent manner. This inhibitory effect was more pronounced when the primary alcohols were more hydrophobic. Secondary or tertiary alcohols had no inhibitory effect. These results provide compelling arguments for PLD activity being upstream of the induction of these genes by SA. A subsequent study of n-butanol effects on the SA-responsive transcriptome identified 1,327 genes differentially expressed upon SA treatment. Strikingly, the SA response of 380 of these genes was inhibited by n-butanol but not by tert-butanol. A detailed analysis of the regulation of these genes showed that PLD could act both positively and negatively, either on gene induction or gene repression. The overlap with the previously described phosphatidylinositol-4-kinase pathway is discussed.
Krinke
Ondrej
O
UPMC Univ Paris 06, Unité de Recherche 5, Centre National de la Recherche Scientifique, Equipe d'Accueil Conventionnée 7180, Laboratoire de Physiologie Cellulaire et Moléculaire des Plantes, F-94200 Ivry-sur-Seine, France.
Flemr
Matyás
M
Vergnolle
Chantal
C
Collin
Sylvie
S
Renou
Jean-Pierre
JP
Taconnat
Ludivine
L
Yu
Agnès
A
Burketová
Lenka
L
Valentová
Olga
O
Zachowski
Alain
A
Ruelland
Eric
E
D020001:1-Butanol / Q000494:pharmacology; D017360:Arabidopsis / Q000201:enzymology* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D004789:Enzyme Activation; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D020411:Oligonucleotide Array Sequence Analysis; D010739:Phospholipase D / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D020156:Salicylic Acid / Q000378:metabolism*; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D020002:tert-Butyl Alcohol / Q000494:pharmacology
D029681:Arabidopsis Proteins; C542190:At5g22570 protein, Arabidopsis; D014157:Transcription Factors; C077262:PR-1 protein, Arabidopsis; D020001:1-Butanol; D010739:Phospholipase D; D020002:tert-Butyl Alcohol; D020156:Salicylic Acid