Phytosphingosine-phosphate is a signal for AtMPK6 activation and Arabidopsis response to chilling

• Published in: The New phytologist Vol. 194; no. 1; pp. 181 - 191
• Main Authors: Dutilleul, Christelle, Ghouziel Benhassaine‐Kesri, Demandre, Chantal, Rézé, Nathalie, Launay, Alban, Pelletier, Sandra, Jean‐Pierre Renou, Zachowski, Alain, Baudouin, Emmanuel, Guillas, Isabelle
• Format: Journal Article
• Language: English
• Published: Oxford, UK New Phytologist Trust 01.04.2012; Blackwell Publishing Ltd; Wiley Subscription Services, Inc; Wiley
• Subjects: Arabidopsis; Arabidopsis - drug effects; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis - physiology; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Cell culture techniques; Cells, Cultured; Chilling; Cold; Cooling; Cultured cells; DNA, Bacterial - genetics; Enzyme Activation - drug effects; Eukaryotes; Freezing; Gene expression; Gene expression regulation; Genetics; Guard cells; Isoforms; Kinases; Life Sciences; long‐chain bases; MAP kinase; Mitogen-Activated Protein Kinases - genetics; Mitogen-Activated Protein Kinases - metabolism; Mutagenesis, Insertional - drug effects; Mutagenesis, Insertional - genetics; Mutants; Mutation - genetics; Phenotypes; Phosphates; Plant cells; Plant growth regulators; Plant Roots - drug effects; Plant Roots - growth & development; Plantlets; Plants; Plants genetics; Protein kinase; Protein Kinase Inhibitors - pharmacology; Radiolabelling; Regulon - genetics; Root growth; Seedlings; Signal Transduction - drug effects; Signal Transduction - genetics; Sphingolipids; Sphingosine - analogs & derivatives; Sphingosine - metabolism; Sphingosine kinase; Stress, Physiological - drug effects; Stress, Physiological - genetics; Synthesis; Arabidopsis thaliana; MAP kinase; chilling; long-chain bases; sphingolipids
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/j.1469-8137.2011.04017.x

Long-chain bases (LCBs) are pleiotropic sphingolipidic signals in eukaryotes. We investigated the source and function of phytosphingosine-1-phosphate (PHS-P), a phospho-LCB rapidly and transiently formed in Arabidopsis thaliana on chilling. PHS-P was analysed by thin-layer chromatography following in vivo metabolic radiolabelling. Pharmacological and genetic approaches were used to identify the sphingosine kinase isoforms involved in cold-responsive PHS-P synthesis. Gene expression, mitogenactivated protein kinase activation and growth phenotypes of three LCB kinase mutants (lcbk1, sphk1 and lcbk2) were studied following cold exposure. Chilling provoked the rapid and transient formation of PHS-P in Arabidopsis cultured cells and plantlets. Cold-evoked PHS-P synthesis was reduced by LCB kinase inhibitors and abolished in the LCB kinase lcbk2 mutant, but not in lcbk1 and sphk1 mutants. lcbk2 presented a constitutive AtMPK6 activation at 22°C. AtMPK6 activation was also triggered by PHS-P treatment independently of PHS/PHS-P balance. lcbk2 mutants grew comparably with wildtype plants at 22 and 4°C, but exhibited a higher root growth at 12°C, correlated with an altered expression of the cold-responsive DELLA gene RGL3. Together, our data indicate a function for LCBK2 in planta. Furthermore, they connect PHS-P formation with plant response to cold, expanding the field of LCB signalling in plants.