Directional intercellular transport of the phytohormone auxin mediated by PIN-FORMED (PIN) efflux carriers has essential roles in both coordinating patterning processes and integrating multiple external cues by rapidly redirecting auxin fluxes. PIN activity is therefore regulated by multiple internal and external cues, for which the underlying molecular mechanisms are not fully elucidated. Here, we demonstrate that 3'-PHOSPHOINOSITIDE-DEPENDENT PROTEIN KINASE1 (PDK1), which is conserved in plants and mammals, functions as a molecular hub that perceives upstream lipid signalling and modulates downstream substrate activity through phosphorylation. Using genetic analysis, we show that the loss-of-function Arabidopsis pdk1.1 pdk1.2 mutant exhibits a plethora of abnormalities in organogenesis and growth due to defective polar auxin transport. Further cellular and biochemical analyses reveal that PDK1 phosphorylates D6 protein kinase, a well-known upstream activator of PIN proteins. We uncover a lipid-dependent phosphorylation cascade that connects membrane-composition-based cellular signalling with plant growth and patterning by regulating morphogenetic auxin fluxes.

• MeSH
• Arabidopsis metabolismus   MeSH
• buněčná membrána metabolismus   MeSH
• fosfolipidy metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• membránové transportní proteiny metabolismus   fyziologie   MeSH
• proteinkinasy PDK fyziologie   MeSH
• proteiny huseníčku fyziologie   MeSH
• regulátory růstu rostlin metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• fosfolipidy MeSH
• kyseliny indoloctové MeSH
• membránové transportní proteiny MeSH
• proteinkinasy PDK MeSH
• proteiny huseníčku MeSH
• regulátory růstu rostlin MeSH

Singlet oxygen produced from triplet excited chlorophylls in photosynthesis is a signal molecule that can induce programmed cell death (PCD) through the action of the OXIDATIVE STRESS INDUCIBLE 1 (OXI1) kinase. Here, we identify two negative regulators of light-induced PCD that modulate OXI1 expression: DAD1 and DAD2, homologs of the human antiapoptotic protein DEFENDER AGAINST CELL DEATH. Overexpressing OXI1 in Arabidopsis (Arabidopsis thaliana) increased plant sensitivity to high light and induced early senescence of mature leaves. Both phenomena rely on a marked accumulation of jasmonate and salicylate. DAD1 or DAD2 overexpression decreased OXI1 expression, jasmonate levels, and sensitivity to photooxidative stress. Knock-out mutants of DAD1 or DAD2 exhibited the opposite responses. Exogenous applications of jasmonate upregulated salicylate biosynthesis genes and caused leaf damage in wild-type plants but not in the salicylate biosynthesis mutant Salicylic acid induction-deficient2, indicating that salicylate plays a crucial role in PCD downstream of jasmonate. Treating plants with salicylate upregulated the DAD genes and downregulated OXI1 We conclude that OXI1 and DAD are antagonistic regulators of cell death through modulating jasmonate and salicylate levels. High light-induced PCD thus results from a tight control of the relative activities of these regulating proteins, with DAD exerting a negative feedback control on OXI1 expression.

• MeSH
• apoptóza genetika   účinky záření   MeSH
• Arabidopsis cytologie   genetika   metabolismus   MeSH
• biosyntetické dráhy účinky léků   genetika   účinky záření   MeSH
• cyklopentany metabolismus   farmakologie   MeSH
• fosfolipasy A1 genetika   metabolismus   MeSH
• kyselina salicylová metabolismus   farmakologie   MeSH
• listy rostlin cytologie   genetika   metabolismus   MeSH
• mutace MeSH
• oxylipiny metabolismus   farmakologie   MeSH
• protein-serin-threoninkinasy genetika   metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulace genové exprese u rostlin účinky léků   účinky záření   MeSH
• regulátory růstu rostlin metabolismus   farmakologie   MeSH
• singletový kyslík metabolismus   MeSH
• stanovení celkové genové exprese metody   MeSH
• světlo MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cyklopentany MeSH
• DAD1 protein, Arabidopsis MeSH Prohlížeč
• fosfolipasy A1 MeSH
• jasmonic acid MeSH Prohlížeč
• kyselina salicylová MeSH
• OXI1 protein, Arabidopsis MeSH Prohlížeč
• oxylipiny MeSH
• protein-serin-threoninkinasy MeSH
• proteiny huseníčku MeSH
• regulátory růstu rostlin MeSH
• singletový kyslík MeSH

Phospholipase D alpha 1 (PLDα1) is a phospholipid hydrolyzing enzyme playing multiple regulatory roles in stress responses of plants. Its signaling activity is mediated by phosphatidic acid (PA) production, capacity to bind, and modulate G-protein complexes or by interaction with other proteins. This work presents a quantitative proteomic analysis of two T-DNA insertion pldα1 mutants of Arabidopsis thaliana. Remarkably, PLDα1 knockouts caused differential regulation of many proteins forming protein complexes, while PLDα1 might be required for their stability. Almost one third of differentially abundant proteins (DAPs) in pldα1 mutants are implicated in metabolism and RNA binding. Latter functional class comprises proteins involved in translation, RNA editing, processing, stability, and decay. Many of these proteins, including those regulating chloroplast protein import and protein folding, share common functions in chloroplast biogenesis and leaf variegation. Consistently, pldα1 mutants showed altered level of TIC40 (a major regulator of protein import into chloroplast), differential accumulation of photosynthetic protein complexes and changed chloroplast sizes as revealed by immunoblotting, blue-native electrophoresis, and microscopic analyses, respectively. Our proteomic analysis also revealed that genetic depletion of PLDα1 also affected proteins involved in cell wall architecture, redox homeostasis, and abscisic acid signaling. Taking together, PLDα1 appears as a protein integrating cytosolic and plastidic protein translations, plastid protein degradation, and protein import into chloroplast in order to regulate chloroplast biogenesis in Arabidopsis.

• Klíčová slova
• Arabidopsis, chloroplast biogenesis, chloroplast protein import, phospholipase D alpha 1, proteomics, translation,
• Publikační typ
• časopisecké články MeSH

Phosphoglycerolipids are essential structural constituents of membranes and some also have important cell signalling roles. In this review, we focus on phosphoglycerolipids that are mediators in hormone signal transduction in plants. We first describe the structures of the main signalling phosphoglycerolipids and the metabolic pathways that generate them, namely the phospholipase and lipid kinase pathways. In silico analysis of Arabidopsis transcriptome data provides evidence that the genes encoding the enzymes of these pathways are transcriptionally regulated in responses to hormones, suggesting some link with hormone signal transduction. The involvement of phosphoglycerolipid signalling in the early responses to abscisic acid, salicylic acid and auxins is then detailed. One of the most important signalling lipids in plants is phosphatidic acid. It can activate or inactivate protein kinases and/or protein phosphatases involved in hormone signalling. It can also activate NADPH oxidase leading to the production of reactive oxygen species. We will interrogate the mechanisms that allow the activation/deactivation of the lipid pathways, in particular the roles of G proteins and calcium. Mediating lipids thus appear as master players of cell signalling, modulating, if not controlling, major transducing steps of hormone signals.

• MeSH
• Arabidopsis fyziologie   MeSH
• fosfolipasy metabolismus   MeSH
• fosfotransferasy metabolismus   MeSH
• glycerofosfolipidy metabolismus   MeSH
• kyselina abscisová metabolismus   MeSH
• kyseliny fosfatidové metabolismus   MeSH
• regulace genové exprese u rostlin MeSH
• regulátory růstu rostlin metabolismus   MeSH
• rostlinné proteiny metabolismus   MeSH
• rostliny MeSH
• signální transdukce fyziologie   MeSH
• transkriptom MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• fosfolipasy MeSH
• fosfotransferasy MeSH
• glycerofosfolipidy MeSH
• kyselina abscisová MeSH
• kyseliny fosfatidové MeSH
• regulátory růstu rostlin MeSH
• rostlinné proteiny MeSH