Constitutive salicylic acid accumulation in pi4kIIIβ1β2 Arabidopsis plants stunts rosette but not root growth

• Published in: The New phytologist 2014-08, Vol.203 (3), p.805-816
• Main Authors: ašek, Vladimír, Janda, Martin, Delage, Elise, Puyaubert, Juliette, Guivarc'h, Anne, López Maseda, Encarnación, Dobrev, Petre I, Caius, José, Bóka, Károly, Valentová, Olga, Burketová, Lenka, Zachowski, Alain, Ruelland, Eric
• Format: Article
• Language: English
• Subjects: 1-Phosphatidylinositol 4-Kinase - genetics; 1-Phosphatidylinositol 4-Kinase - metabolism; Arabidopsis; Arabidopsis - anatomy & histology; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Biosynthesis; Disease Resistance - genetics; Disease Resistance - immunology; DNA microarrays; Down-Regulation - genetics; dwarf phenotype; gene expression; Gene Expression Regulation, Plant; Genes; genetic markers; Genetic mutation; Genome, Plant; Genotype; Genotype & phenotype; Growth; hormone transduction; Hormones; Kinases; Kinetics; Leaves; Lipid Metabolism - genetics; microarray technology; Models, Genetic; Mutants; Mutation; Mutation - genetics; Nucleotide sequence; PCR; Phenotype; Phenotypes; Phosphatidylinositol; phosphatidylinositol‐4‐kinases (PI4Ks); Phospholipids; Plant Diseases - genetics; Plant Diseases - immunology; Plant Diseases - microbiology; Plant growth; Plant growth regulators; Plant growth substances; Plant hormones; Plant Leaves - genetics; Plant Leaves - growth & development; Plant roots; Plant Roots - anatomy & histology; Plant Roots - growth & development; Plant Shoots - growth & development; Plants; Polymerase chain reaction; PR‐1; Pseudomonas - physiology; Pseudomonas syringae; Reactive Oxygen Species - metabolism; resistance; reverse transcriptase polymerase chain reaction; Reverse transcription; root growth; Rosette; Salicylic acid; salicylic acid (SA); Salicylic Acid - metabolism; Seedlings; Signal Transduction; Signaling; Transcription; Up-Regulation - genetics
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.12822

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.