Constitutive salicylic acid accumulation in pi4kIIIβ1β2 Arabidopsis plants stunts rosette but not root growth.
Phospholipids have recently been found to be integral elements of hormone signalling pathways. An Arabidopsis thaliana double mutant in two type III phosphatidylinositol-4-kinases (PI4Ks), pi4kIIIβ1β2, displays a stunted rosette growth. The causal link between PI4K activity and growth is unknown. Using microarray analysis, quantitative reverse transcription polymerase chain reaction (RT-qPCR) and multiple phytohormone analysis by LC-MS we investigated the mechanism responsible for the pi4kIIIβ1β2 phenotype. The pi4kIIIβ1β2 mutant accumulated a high concentration of salicylic acid (SA), constitutively expressed SA marker genes including PR-1, and was more resistant to Pseudomonas syringae. pi4kIIIβ1β2 was crossed with SA signalling mutants eds1 and npr1 and SA biosynthesis mutant sid2 and NahG. The dwarf phenotype of pi4kIIIβ1β2 rosettes was suppressed in all four triple mutants. Whereas eds1 pi4kIIIβ1β2, sid2 pi4kIIIβ1β2 and NahG pi4kIIIβ1β2 had similar amounts of SA as the wild-type (WT), npr1pi4kIIIβ1β2 had more SA than pi4kIIIβ1β2 despite being less dwarfed. This indicates that PI4KIIIβ1 and PI4KIIIβ2 are genetically upstream of EDS1 and need functional SA biosynthesis and perception through NPR1 to express the dwarf phenotype. The slow root growth phenotype of pi4kIIIβ1β2 was not suppressed in any of the triple mutants. The pi4kIIIβ1β2 mutations together cause constitutive activation of SA signalling that is responsible for the dwarf rosette phenotype but not for the short root phenotype.
Institute of Experimental Botany, Academy of Sciences of Czech Republic, Prague, 165 02, Czech Republic.
Vladimír
V
Sašek
Martin
M
Janda
Elise
E
Delage
Juliette
J
Puyaubert
Anne
A
Guivarc'h
Encarnación
E
López Maseda
Petre I
PI
Dobrev
José
J
Caius
Károly
K
Bóka
Olga
O
Valentová
Lenka
L
Burketová
Alain
A
Zachowski
Eric
E
Ruelland
D019870:1-Phosphatidylinositol 4-Kinase / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000033:anatomy & histology / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D060467:Disease Resistance / Q000235:genetics / Q000276:immunology; D015536:Down-Regulation / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D005838:Genotype; D007700:Kinetics; D050356:Lipid Metabolism / Q000235:genetics; D008957:Models, Genetic; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development*; D018517:Plant Roots / Q000033:anatomy & histology / Q000254:growth & development*; D018520:Plant Shoots / Q000254:growth & development; D011549:Pseudomonas / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism*; D015398:Signal Transduction; D015854:Up-Regulation / Q000235:genetics
D029681:Arabidopsis Proteins; D017382:Reactive Oxygen Species; D019870:1-Phosphatidylinositol 4-Kinase; C000596017:PI4KIIIbeta1 protein, Arabidopsis; C000596018:PI4KIIIbeta2 protein, Arabidopsis; D020156:Salicylic Acid
Arabidopsis; PR-1; dwarf phenotype; hormone transduction; phosphatidylinositol-4-kinases (PI4Ks); resistance; salicylic acid (SA)