Plant phospholipase Ds (PLDs), essential regulators of phospholipid signaling, function in multiple signal transduction cascades; however, the mechanisms regulating PLDs in response to pathogens remain unclear. Here, we found that Arabidopsis (Arabidopsis thaliana) PLDδ accumulated in cells at the entry sites of the barley powdery mildew fungus, Blumeria graminis f. sp hordei Using fluorescence recovery after photobleaching and single-molecule analysis, we observed higher PLDδ density in the plasma membrane after chitin treatment; PLDδ also underwent rapid exocytosis. Fluorescence resonance energy transfer with fluorescence lifetime imaging microscopy showed that the interaction between PLDδ and the microdomain marker AtREMORIN1.3 (AtREM1.3) increased in response to chitin, indicating that exocytosis facilitates rapid, efficient sorting of PLDδ into microdomains upon pathogen stimulus. We further unveiled a trade-off between brefeldin A (BFA)-resistant and -sensitive pathways in secretion of PLDδ under diverse conditions. Upon pathogen attack, PLDδ secretion involved syntaxin-associated VAMP721/722-mediated exocytosis sensitive to BFA. Analysis of phosphatidic acid (PA), hydrogen peroxide, and jasmonic acid (JA) levels and expression of related genes indicated that the relocalization of PLDδ is crucial for its activation to produce PA and initiate reactive oxygen species and JA signaling pathways. Together, our findings revealed that the translocation of PLDδ to papillae is modulated by exocytosis, thus triggering PA-mediated signaling in plant innate immunity.plantcell;31/12/3015/FX1F1fx1.

• MeSH
• Arabidopsis genetics   immunology   metabolism   microbiology   MeSH
• Ascomycota pathogenicity   MeSH
• Brefeldin A immunology   metabolism   MeSH
• Cell Membrane metabolism   MeSH
• Chitin immunology   metabolism   MeSH
• Cyclopentanes metabolism   MeSH
• Exocytosis drug effects   immunology   MeSH
• Phospholipase D genetics   metabolism   MeSH
• Phosphatidic Acids metabolism   MeSH
• Plant Diseases immunology   microbiology   MeSH
• Oxylipins metabolism   MeSH
• Hydrogen Peroxide metabolism   MeSH
• Immunity, Innate * drug effects   MeSH
• Arabidopsis Proteins metabolism   MeSH
• Qa-SNARE Proteins metabolism   MeSH
• R-SNARE Proteins metabolism   MeSH
• SNARE Proteins genetics   metabolism   MeSH
• Reactive Oxygen Species metabolism   MeSH
• Signal Transduction immunology   physiology   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Brefeldin A MeSH
• Chitin MeSH
• Cyclopentanes MeSH
• Phospholipase D MeSH
• jasmonic acid MeSH Browser
• Phosphatidic Acids MeSH
• Oxylipins MeSH
• PEN1 protein, Arabidopsis MeSH Browser
• Hydrogen Peroxide MeSH
• phospholipase D delta MeSH Browser
• Arabidopsis Proteins MeSH
• Qa-SNARE Proteins MeSH
• R-SNARE Proteins MeSH
• SNARE Proteins MeSH
• Reactive Oxygen Species MeSH
• REM1 protein, Arabidopsis MeSH Browser
• VAMP721 protein, Arabidopsis MeSH Browser
• VAMP722 protein, Arabidopsis MeSH Browser

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.

• Keywords
• cellular functions, phosphatidic acid, phospholipase A, phospholipase C, phospholipase D, phospholipases, phytohormones, plant development,
• Publication type
• Journal Article MeSH
• Review 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.

• Keywords
• Arabidopsis, chloroplast biogenesis, chloroplast protein import, phospholipase D alpha 1, proteomics, translation,
• Publication type
• Journal Article MeSH

Phospholipase Dα1 (PLDα1) belongs to phospholipases, a large phospholipid hydrolyzing protein family. PLDα1 has a substrate preference for phosphatidylcholine leading to enzymatic production of phosphatidic acid, a lipid second messenger with multiple cellular functions. PLDα1 itself is implicated in biotic and abiotic stress responses. Here, we present a shot-gun differential proteomic analysis on roots of two Arabidopsis pldα1 mutants compared to the wild type. Interestingly, PLDα1 deficiency leads to altered abundances of proteins involved in diverse processes related to membrane transport including endocytosis and endoplasmic reticulum-Golgi transport. PLDα1 may be involved in the stability of attachment sites of endoplasmic reticulum to the plasma membrane as suggested by increased abundance of synaptotagmin 1, which was validated by immunoblotting and whole-mount immunolabelling analyses. Moreover, we noticed a robust abundance alterations of proteins involved in mitochondrial import and electron transport chain. Notably, the abundances of numerous proteins implicated in glucosinolate biosynthesis were also affected in pldα1 mutants. Our results suggest a broader biological involvement of PLDα1 than anticipated thus far, especially in the processes such as endomembrane transport, mitochondrial protein import and protein quality control, as well as glucosinolate biosynthesis.

• Keywords
• Arabidopsis, cytoskeleton, mitochondrial protein import, phospholipase D alpha1, proteomics, quality control, vesicular transport,
• MeSH
• Arabidopsis metabolism   MeSH
• Endocytosis MeSH
• Phospholipase D genetics   metabolism   MeSH
• Gene Ontology MeSH
• Glucosinolates biosynthesis   MeSH
• Plant Roots metabolism   MeSH
• Mitochondrial Proteins metabolism   MeSH
• Arabidopsis Proteins genetics   metabolism   MeSH
• Proteome metabolism   MeSH
• Proteomics * MeSH
• Synaptotagmin I metabolism   MeSH
• Tandem Mass Spectrometry MeSH
• Protein Transport MeSH
• Uncoupling Protein 1 metabolism   MeSH
• Chromatography, High Pressure Liquid MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Phospholipase D MeSH
• Glucosinolates MeSH
• Mitochondrial Proteins MeSH
• PLDA1 protein, Arabidopsis MeSH Browser
• Arabidopsis Proteins MeSH
• Proteome MeSH
• Synaptotagmin I MeSH
• SYT1 protein, Arabidopsis MeSH Browser
• Uncoupling Protein 1 MeSH

Phospholipase D alpha 1 (PLDα1, At3g15730) and its product phosphatidic acid (PA) are involved in a variety of cellular and physiological processes, such as cytoskeletal remodeling, regulation of stomatal closure and opening, as well as biotic and abiotic stress signaling. Here we aimed to study developmental expression patterns and subcellular localization of PLDα1 in Arabidopsis using advanced microscopy methods such as light-sheet fluorescence microscopy (LSFM) and structured illumination microscopy (SIM). We complemented two knockout pldα1 mutants with a YFP-tagged PLDα1 expressed under the PLDα1 native promoter in order to study developmental expression pattern and subcellular localization of PLDα1 in Arabidopsis thaliana under natural conditions. Imaging of tissue-specific and developmentally-regulated localization of YFP-tagged PLDα1 by LSFM in roots of growing seedlings showed accumulation of PLDα1-YFP in the root cap and the rhizodermis. Expression of PLDα1-YFP in the rhizodermis was considerably higher in trichoblasts before and during root hair formation and growth. Thus, PLDα1-YFP accumulated in emerging root hairs and in the tips of growing root hairs. PLDα1-YFP showed cytoplasmic subcellular localization in root cap cells and in cells of the root transition zone. In aerial parts of plants PLDα1-YFP was also localized in the cytoplasm showing enhanced accumulation in the cortical cytoplasmic layer of epidermal non-dividing cells of hypocotyls, leaves, and leaf petioles. However, in dividing cells of root apical meristem and leaf petiole epidermis PLDα1-YFP was enriched in mitotic spindles and phragmoplasts, as revealed by co-visualization with microtubules. Finally, super-resolution SIM imaging revealed association of PLDα1-YFP with both microtubules and clathrin-coated vesicles (CCVs) and pits (CCPs). In conclusion, this study shows the developmentally-controlled expression and subcellular localization of PLDα1 in dividing and non-dividing Arabidopsis cells.

• Keywords
• Arabidopsis thaliana, At3g15730, development, light-sheet fluorescence microscopy, localization, microtubules, phospholipase D,
• Publication type
• Journal Article MeSH

The actin cytoskeleton plays a key role in the plant morphogenesis and is involved in polar cell growth, movement of subcellular organelles, cell division, and plant defense. Organization of actin cytoskeleton undergoes dynamic remodeling in response to internal developmental cues and diverse environmental signals. This dynamic behavior is regulated by numerous actin-binding proteins (ABPs) that integrate various signaling pathways. Production of the signaling lipids phosphatidylinositol 4,5-bisphosphate and phosphatidic acid affects the activity and subcellular distribution of several ABPs, and typically correlates with increased actin polymerization. Here we review current knowledge of the inter-regulatory dynamics between signaling phospholipids and the actin cytoskeleton in plant cells.

• Keywords
• actin, actin-binding proteins, capping protein, cytoskeleton, phosphatidic acid, phosphatidylinositol 4,5-bisphosphate, phospholipase D, signaling,
• Publication type
• Journal Article MeSH
• Review MeSH