Flagellin perception is a keystone of pattern-triggered immunity in plants. The recognition of this protein by a plasma membrane (PM) receptor complex is the beginning of a signaling cascade that includes protein phosphorylation and the production of reactive oxygen species (ROS). In both Arabidopsis (Arabidopsis thaliana) seedlings and suspension cells, we found that treatment with flg22, a peptide corresponding to the most conserved domain of bacterial flagellin, caused a rapid and transient decrease in the level of phosphatidylinositol (PI) 4,5-bisphosphate along with a parallel increase in phosphatidic acid (PA). In suspension cells, inhibitors of either phosphoinositide-dependent phospholipases C (PLC) or diacylglycerol kinases (DGKs) inhibited flg22-triggered PA production and the oxidative burst. In response to flg22, receptor-like kinase-deficient fls2, bak1, and bik1 mutants (FLAGELLIN SENSITIVE 2, BRASSINOSTEROID INSENSITIVE 1-associated kinase 1, and BOTRYTIS-INDUCED KINASE 1, respectively) produced less PA than wild-type (WT) plants, whereas this response did not differ in NADPH oxidase-deficient rbohD (RESPIRATORY BURST OXIDASE HOMOLOG D) plants. Among the DGK-deficient lines tested, the dgk5.1 mutant produced less PA and less ROS after flg22 treatment compared with WT seedlings. In response to flg22, dgk5.1 plants showed lower callose accumulation and impaired resistance to Pseudomonas syringae pv. tomato DC3000 hrcC-. Transcriptomics revealed that the basal expression of defense-related genes was altered in dgk5.1 seedlings compared with the WT. A GFP-DGK5 fusion protein localized to the PM, where RBOHD and PLC2 (proteins involved in plant immunity) are also located. The role of DGK5 and its enzymatic activity in flagellin signaling and fine-tuning of early immune responses in plant-microbe interactions is discussed.

• MeSH
• Arabidopsis * metabolismus   MeSH
• diacylglycerolkinasa genetika   metabolismus   MeSH
• flagelin farmakologie   genetika   MeSH
• imunita rostlin MeSH
• protein-serin-threoninkinasy MeSH
• proteiny huseníčku * genetika   metabolismus   MeSH
• Pseudomonas syringae fyziologie   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• BIK1 protein, Arabidopsis MeSH Prohlížeč
• diacylglycerolkinasa MeSH
• flagelin MeSH
• protein-serin-threoninkinasy MeSH
• proteiny huseníčku * MeSH
• reaktivní formy kyslíku MeSH

Phospholipases (PLs) are lipid-hydrolyzing enzymes known to have diverse signaling roles during plant abiotic and biotic stress responses. They catalyze lipid remodeling, which is required to generate rapid responses of plants to environmental cues. Moreover, they produce second messenger molecules, such as phosphatidic acid (PA) and thus trigger or modulate signaling cascades that lead to changes in gene expression. The roles of phospholipases in plant abiotic and biotic stress responses have been intensively studied. Nevertheless, emerging evidence suggests that they also make significant contributions to plants' cellular and developmental processes. In this mini review, we summarized recent advances in the study of the cellular and developmental roles of phospholipases in plants.

• Klíčová slova
• cellular functions, phosphatidic acid, phospholipase A, phospholipase C, phospholipase D, phospholipases, phytohormones, plant development,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

BACKGROUND AND AIMS: The non-specific phospholipase C (NPC) is a new member of the plant phospholipase family that reacts to abiotic environmental stresses, such as phosphate deficiency, high salinity, heat and aluminium toxicity, and is involved in root development, silicon distribution and brassinolide signalling. Six NPC genes (NPC1-NPC6) are found in the Arabidopsis genome. The NPC2 isoform has not been experimentally characterized so far. METHODS: The Arabidopsis NPC2 isoform was cloned and heterologously expressed in Escherichia coli. NPC2 enzyme activity was determined using fluorescent phosphatidylcholine as a substrate. Tissue expression and subcellular localization were analysed using GUS- and GFP-tagged NPC2. The expression patterns of NPC2 were analysed via quantitative real-time PCR. Independent homozygous transgenic plant lines overexpressing NPC2 under the control of a 35S promoter were generated, and reactive oxygen species were measured using a luminol-based assay. KEY RESULTS: The heterologously expressed protein possessed phospholipase C activity, being able to hydrolyse phosphatidylcholine to diacylglycerol. NPC2 tagged with GFP was predominantly localized to the Golgi apparatus in Arabidopsis roots. The level of NPC2 transcript is rapidly altered during plant immune responses and correlates with the activation of multiple layers of the plant defence system. Transcription of NPC2 decreased substantially after plant infiltration with Pseudomonas syringae, flagellin peptide flg22 and salicylic acid treatments and expression of the effector molecule AvrRpm1. The decrease in NPC2 transcript levels correlated with a decrease in NPC2 enzyme activity. NPC2-overexpressing mutants showed higher reactive oxygen species production triggered by flg22. CONCLUSIONS: This first experimental characterization of NPC2 provides new insights into the role of the non-specific phospholipase C protein family. The results suggest that NPC2 is involved in the response of Arabidopsis to P. syringae attack.

• Klíčová slova
• Arabidopsis thaliana, MAMP-triggered immunity, Pseudomonas syringae, effector-triggered immunity, flagellin, non-specific phospholipase C, phosphatidylcholine-specific phospholipase C, reactive oxygen species,
• MeSH
• Arabidopsis enzymologie   imunologie   mikrobiologie   MeSH
• fosfatidylcholiny metabolismus   MeSH
• fosfolipasy typu C genetika   fyziologie   MeSH
• Golgiho aparát enzymologie   MeSH
• imunita rostlin fyziologie   MeSH
• klonování DNA MeSH
• konfokální mikroskopie MeSH
• kvantitativní polymerázová řetězová reakce MeSH
• nemoci rostlin imunologie   mikrobiologie   MeSH
• proteiny huseníčku genetika   fyziologie   MeSH
• protoplasty enzymologie   MeSH
• Pseudomonas syringae * MeSH
• reaktivní formy kyslíku MeSH
• regulace genové exprese u rostlin MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• fosfatidylcholiny MeSH
• fosfolipasy typu C MeSH
• NPC2 protein, Arabidopsis MeSH Prohlížeč
• proteiny huseníčku MeSH
• reaktivní formy kyslíku MeSH