301
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Kusano H, Testerink C, Vermeer JEM, Tsuge T, Shimada H, Oka A, Munnik T, Aoyama T. The Arabidopsis Phosphatidylinositol Phosphate 5-Kinase PIP5K3 is a key regulator of root hair tip growth. THE PLANT CELL 2008; 20:367-80. [PMID: 18281506 PMCID: PMC2276443 DOI: 10.1105/tpc.107.056119] [Citation(s) in RCA: 158] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] functions as a site-specific signal on membranes to promote cytoskeletal reorganization and membrane trafficking. Localization of PtdIns(4,5)P2 to apices of growing root hairs and pollen tubes suggests that it plays an important role in tip growth. However, its regulation and mode of action remain unclear. We found that Arabidopsis thaliana PIP5K3 (for Phosphatidylinositol Phosphate 5-Kinase 3) encodes a phosphatidylinositol 4-phosphate 5-kinase, a key enzyme producing PtdIns(4,5)P2, that is preferentially expressed in growing root hairs. T-DNA insertion mutations that substantially reduced the expression of PIP5K3 caused significantly shorter root hairs than in the wild type. By contrast, overexpression caused longer root hairs and multiple protruding sites on a single trichoblast. A yellow fluorescent protein (YFP) fusion of PIP5K3, driven by the PIP5K3 promoter, complemented the short-root-hair phenotype. PIP5K3-YFP localized to the plasma membrane and cytoplasmic space of elongating root hair apices, to growing root hair bulges, and, notably, to sites about to form root hair bulges. The signal was greatest in rapidly growing root hairs and quickly disappeared when elongation ceased. These results provide evidence that PIP5K3 is involved in localizing PtdIns(4,5)P2 to the elongating root hair apex and is a key regulator of the machinery that initiates and promotes root hair tip growth.
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Affiliation(s)
- Hiroaki Kusano
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
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302
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Distéfano AM, García-Mata C, Lamattina L, Laxalt AM. Nitric oxide-induced phosphatidic acid accumulation: a role for phospholipases C and D in stomatal closure. PLANT, CELL & ENVIRONMENT 2008; 31:187-94. [PMID: 17996010 DOI: 10.1111/j.1365-3040.2007.01756.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Stomatal closure is regulated by a complex network of signalling events involving numerous intermediates, among them nitric oxide (NO). Little is known about the signalling events occurring downstream of NO. Previous studies have shown that NO modulates cytosolic calcium concentration and the activation of plasma membrane ion channels. Here we provide evidence that supports the involvement of the lipid second messenger phosphatidic acid (PA) in NO signalling during stomatal closure. PA levels in Vicia faba epidermal peels increased upon NO treatment to maximum levels within 30 min, subsequently decreasing to control levels at 60 min. PA can be generated via phospholipase D (PLD) or via phospholipase C (PLC) in concerted action with diacylglycerol kinase (DGK). Our results showed that NO-induced PA is produced via the activation of both pathways. NO-induced stomatal closure was blocked either when PLC or PLD activity was inhibited. We have shown that PLC- and PLD-derived PA represents a downstream component of NO signalling cascade during stomatal closure.
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Affiliation(s)
- Ayelen M Distéfano
- Instituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata, CC 1245, 7600 Mar del Plata, Argentina
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303
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Tuteja N, Sopory SK. Plant signaling in stress: G-protein coupled receptors, heterotrimeric G-proteins and signal coupling via phospholipases. PLANT SIGNALING & BEHAVIOR 2008; 3:79-86. [PMID: 19516978 PMCID: PMC2633988 DOI: 10.4161/psb.3.2.5303] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2007] [Accepted: 11/13/2007] [Indexed: 05/20/2023]
Abstract
Plant growth and development are coordinalely controlled by several internal factors and environmental signals. To sense these environmental signals, the higher plants have evolved a complex signaling network, which may also cross talk with each other. Plants can respond to the signals as individual cells and as whole organisms. Various receptors including phytochromes, G-proteins coupled receptors (GPCR), kinase and hormone receptors play important role in signal transduction but very few have been characterized in plant system. The heterotrimeric G-proteins mediate the coupling of signal transduction from activated GPCR to appropriate downstream effectors and thereby play an important role in signaling. In this review we have focused on some of the recent work on G-proteins and two of the effectors, PLC and PLD, which have been shown to interact with Galpha subunit and also discussed their role in abiotic stress tolerance.
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Affiliation(s)
- Narendra Tuteja
- Plant Molecular Biology Group; International Centre for Genetic Engineering and Biotechnology (ICGEB); Aruna Asaf Ali Marg; New Delhi, India
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304
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Komis G, Galatis B, Quader H, Galanopoulou D, Apostolakos P. Phospholipase C signaling involvement in macrotubule assembly and activation of the mechanism regulating protoplast volume in plasmolyzed root cells of Triticum turgidum. THE NEW PHYTOLOGIST 2008; 178:267-282. [PMID: 18221245 DOI: 10.1111/j.1469-8137.2007.02363.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The role of phosphoinositide-specific phospholipase C (PI-PLC) signaling in the macrotubule-dependent protoplast volume regulation in plasmolyzed root cells of Triticum turgidum was investigated. At the onset of hyperosmotic stress, PI-PLC activation was documented. Inhibition of PI-PLC activity by U73122 blocked tubulin macrotubule formation in plasmolyzed cells and their protoplast volume regulatory mechanism. In neomycin-treated plasmolyzed cells, macrotubule formation and protoplast volume regulation were not affected. In these cells the PI-PLC pathway is down-regulated as neomycin sequesters the PI-PLC substrate, 4,5-diphosphate-phosphatidyl inositol (PtdInsP(2)). These phenomena were unaffected by R59022, an inhibitor of phosphatidic acic (PA) production via the PLC pathway. Taxol, a microtubule (MT) stabilizer, inhibited the hyperosmotic activation of PI-PLC, but oryzalin, which disorganized MTs, triggered PI-PLC activity. Taxol prevented macrotubule formation and inhibited the mechanism regulating the volume of the plasmolyzed protoplast. Neomycin partly relieved some of the taxol effects. These data suggest that PtdInspP(2) turnover via PI-PLC assists macrotubule formation and activation of the mechanism regulating the plasmolyzed protoplast volume; and the massive disorganization of MTs that is carried out at the onset of hyperosmotic treatment triggers the activation of this mechanism.
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Affiliation(s)
- George Komis
- Department of Botany, Faculty of Biology, University of Athens, Athens 15784, Greece
| | - Basil Galatis
- Department of Botany, Faculty of Biology, University of Athens, Athens 15784, Greece
| | - Hartmut Quader
- Biocenter Klein Flottbek, University of Hamburg, D-22609 Hamburg, Germany
| | - Dia Galanopoulou
- Laboratory of Biochemistry, Faculty of Chemistry, University of Athens, Athens, 157 71, Greece
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305
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Abstract
DGKs (diacylglycerol kinases) are members of a unique and conserved family of intracellular lipid kinases that phosphorylate DAG (diacylglycerol), catalysing its conversion into PA (phosphatidic acid). This reaction leads to attenuation of DAG levels in the cell membrane, regulating a host of intracellular signalling proteins that have evolved the ability to bind this lipid. The product of the DGK reaction, PA, is also linked to the regulation of diverse functions, including cell growth, membrane trafficking, differentiation and migration. In multicellular eukaryotes, DGKs provide a link between lipid metabolism and signalling. Genetic experiments in Caenorhabditis elegans, Drosophila melanogaster and mice have started to unveil the role of members of this protein family as modulators of receptor-dependent responses in processes such as synaptic transmission and photoreceptor transduction, as well as acquired and innate immune responses. Recent discoveries provide new insights into the complex mechanisms controlling DGK activation and their participation in receptor-regulated processes. After more than 50 years of intense research, the DGK pathway emerges as a key player in the regulation of cell responses, offering new possibilities of therapeutic intervention in human pathologies, including cancer, heart disease, diabetes, brain afflictions and immune dysfunctions.
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306
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Cheung AY, Wu HM. Structural and signaling networks for the polar cell growth machinery in pollen tubes. ANNUAL REVIEW OF PLANT BIOLOGY 2008; 59:547-72. [PMID: 18444907 DOI: 10.1146/annurev.arplant.59.032607.092921] [Citation(s) in RCA: 188] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Pollen tubes elongate within the pistil to transport sperms to the female gametophytes for fertilization. Pollen tubes grow at their tips through a rapid and polarized cell growth process. This tip growth process is supported by an elaborate and dynamic actin cytoskeleton and a highly active membrane trafficking system that together provide the driving force and secretory activities needed for growth. A polarized cytoplasm with an abundance of vesicles and tip-focused Ca(2+) and H(+) concentration gradients are important for the polar cell growth process. Apical membrane-located Rho GTPases regulate Ca(2+) concentration and actin dynamics in the cytoplasm and are crucial for maintaining pollen tube polarity. Pollen tube growth is marked by periods of rapid and slow growth phases. Activities that regulate and support this tip growth process also show oscillatory fluctuations. How these activities correlate with the rapid, polar, and oscillatory pollen tube growth process is discussed.
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Affiliation(s)
- Alice Y Cheung
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003, USA.
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307
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Ishida T, Kurata T, Okada K, Wada T. A genetic regulatory network in the development of trichomes and root hairs. ANNUAL REVIEW OF PLANT BIOLOGY 2008; 59:365-86. [PMID: 18257710 DOI: 10.1146/annurev.arplant.59.032607.092949] [Citation(s) in RCA: 342] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Trichomes and root hairs differentiate from epidermal cells in the aerial tissues and roots, respectively. Because trichomes and root hairs are easily accessible, particularly in the model plant Arabidopsis, their development has become a well-studied model of cell differentiation and growth. Molecular genetic analyses using Arabidopsis mutants have demonstrated that the differentiation of trichomes and root hair/hairless cells is regulated by similar molecular mechanisms. Transcriptional complexes regulate differentiation into trichome cells and root hairless cells, and formation of the transcriptional complexes is inhibited in neighboring cells. Control of cell growth after fate determination has also been analyzed using Arabidopsis mutants. The progression of endoreduplication cycles, reorientation of microtubules, and organization of the actin cytoskeleton play important roles in trichome growth. Various cellular components such as ion channels, the actin cytoskeleton, microtubules and cell wall materials, and intracellular signal transduction act to establish and maintain root hair tip growth.
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Affiliation(s)
- Tetsuya Ishida
- Plant Science Center, RIKEN, Yokohama, Kanagawa 230-0045, Japan.
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308
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Stenzel I, Ischebeck T, König S, Hołubowska A, Sporysz M, Hause B, Heilmann I. The type B phosphatidylinositol-4-phosphate 5-kinase 3 is essential for root hair formation in Arabidopsis thaliana. THE PLANT CELL 2008; 20:124-41. [PMID: 18178770 PMCID: PMC2254927 DOI: 10.1105/tpc.107.052852] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Root hairs are extensions of root epidermal cells and a model system for directional tip growth of plant cells. A previously uncharacterized Arabidopsis thaliana phosphatidylinositol-4-phosphate 5-kinase gene (PIP5K3) was identified and found to be expressed in the root cortex, epidermal cells, and root hairs. Recombinant PIP5K3 protein was catalytically active and converted phosphatidylinositol-4-phosphate to phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P2]. Arabidopsis mutant plants homozygous for T-DNA-disrupted PIP5K3 alleles were compromised in root hair formation, a phenotype complemented by expression of wild-type PIP5K3 cDNA under the control of a 1500-bp PIP5K3 promoter fragment. Root hair-specific PIP5K3 overexpression resulted in root hair deformation and loss of cell polarity with increasing accumulation of PIP5K3 transcript. Using reestablishment of root hair formation in T-DNA mutants as a bioassay for physiological functionality of engineered PIP5K3 variants, catalytic activity was found to be essential for physiological function, indicating that PtdIns(4,5)P2 formation is required for root hair development. An N-terminal domain containing membrane occupation and recognition nexus repeats, which is not required for catalytic activity, was found to be essential for the establishment of root hair growth. Fluorescence-tagged PIP5K3 localized to the periphery of the apical region of root hair cells, possibly associating with the plasma membrane and/or exocytotic vesicles. Transient heterologous expression of full-length PIP5K3 in tobacco (Nicotiana tabacum) pollen tubes increased plasma membrane association of a PtdIns(4,5)P2-specific reporter in these tip-growing cells. The data demonstrate that root hair development requires PIP5K3-dependent PtdIns(4,5)P2 production in the apical region of root hair cells.
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Affiliation(s)
- Irene Stenzel
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, 37077 Göttingen, Germany
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309
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Regente M, Corti Monzón G, de la Canal L. Phospholipids are present in extracellular fluids of imbibing sunflower seeds and are modulated by hormonal treatments. JOURNAL OF EXPERIMENTAL BOTANY 2008; 59:553-62. [PMID: 18212025 DOI: 10.1093/jxb/erm329] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Phospholipids are well known messengers involved in developmental and stress responses mediating intracellular signalling. It has been hypothesized that phospholipids exist which could participate in intercellular communication events through the apoplast of sunflower (Helianthus annuus) seeds. Here it is shown that extracellular washing fluids (EWFs) obtained from seeds imbibed for 2 h contain diverse phospholipids. Lipid profiling by electrospray ionization tandem mass spectrometry revealed that the EWFs have a particular composition, with phosphatidic acid (PA) and phosphatidylinositol (PI) being the major phospholipids. These profiles are clearly distinct from those of seed extract (SE), and comparative SDS-PAGE of EWF and SE, followed by intracellular and plasma membrane marker analyses, allowed a significant contamination of the EWF to be discarded. Treatment of the seeds with 100 microM jasmonic acid (JA) induces changes in the profile of EWF phospholipids, leading to a decrease in PI content, while the accumulation of phosphatidylinositol 4-phosphate (PI4P) and specific PA species is observed. On the other hand, the EWF from seeds subjected to 50 microM abscisic acid (ABA) treatment exhibit an increase in PA and phosphatidylglycerol levels. To our knowledge, this is the first report on the existence of phospholipids as extracellular components of seeds. Moreover, the modulation of PA, PI, and PI4P levels by hormonal treatments further suggests their contribution to intercellular communication in planta.
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Affiliation(s)
- Mariana Regente
- Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, CC 1245, 7600 Mar del Plata, Buenos Aires, Argentina.
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310
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Gadjev I, Stone JM, Gechev TS. Programmed cell death in plants: new insights into redox regulation and the role of hydrogen peroxide. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 270:87-144. [PMID: 19081535 DOI: 10.1016/s1937-6448(08)01403-2] [Citation(s) in RCA: 206] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Programmed cell death (PCD), the highly regulated dismantling of cells, is essential for plant growth and survival. PCD plays key roles in embryo development, formation and maturation of many cell types and tissues, and plant reaction/adaptation to environmental conditions. Reactive oxygen species (ROS) are not only toxic by products of aerobic metabolism with strictly controlled cellular levels, but they also function as signaling agents regulating many biological processes and producing pleiotropic effects. Over the last decade, ROS have become recognized as important modulators of plant PCD. Molecular genetic approaches using plant mutants and transcriptome studies related to ROS-mediated PCD have revealed a wide array of plant-specific cell death regulators and have contributed to unraveling the elaborate redox signaling network. This review summarizes the biological processes, in which plant PCD participates and discusses the signaling functions of ROS with emphasis on hydrogen peroxide.
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Affiliation(s)
- Ilya Gadjev
- Department of Plant Physiology and Plant Molecular Biology, University of Plovdiv, Plovdiv 4000, Bulgaria
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311
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van Leeuwen W, Vermeer JEM, Gadella TWJ, Munnik T. Visualization of phosphatidylinositol 4,5-bisphosphate in the plasma membrane of suspension-cultured tobacco BY-2 cells and whole Arabidopsis seedlings. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 52:1014-26. [PMID: 17908156 DOI: 10.1111/j.1365-313x.2007.03292.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] is an important signalling lipid in mammalian cells, where it functions as a second-messenger precursor in response to agonist-dependent activation of phospholipase C (PLC) but also operates as a signalling molecule on its own. Much of the recent knowledge about it has come from a new technique to visualize PtdIns(4,5)P(2)in vivo, by expressing a green or yellow fluorescent protein (GFP or YFP) fused to the pleckstrin homology (PH) domain of human PLCdelta1 that specifically binds PtdIns(4,5)P(2). In this way, YFP-PH(PLCdelta1) has been shown to predominantly label the plasma membrane and to transiently translocate into the cytoplasm upon PLC activation in a variety of mammalian cell systems. In plants, biochemical studies have shown that PtdIns(4,5)P(2) is present in very small quantities, but knowledge of its localization and function is still very limited. In this study, we have used YFP-PH(PLCdelta1) to try monitoring PtdIns(4,5)P(2)/PLC signalling in stably-transformed tobacco Bright Yellow-2 (BY-2) cells and Arabidopsis seedlings. In both plant systems, no detrimental effects were observed, indicating that overexpression of the biosensor did not interfere with the function of PtdIns(4,5)P(2). Confocal imaging revealed that most of the YFP-PH(PLCdelta1) fluorescence was present in the cytoplasm, and not in the plasma membrane as in mammalian cells. Nonetheless, four conditions were found in which YFP-PH(PLCdelta1) was concentrated at the plasma membrane: (i) upon treatment with the PLC inhibitor U73122; (ii) in response to salt stress; (iii) as a gradient at the tip of growing root hairs; (iv) during the final stage of a BY-2 cell division. We conclude that PtdIns(4,5)P(2), as in animals, is present in the plasma membrane of plants, but that its concentration in most cells is too low to be detected by YFP-PH(PLCdelta1). Hence, the reporter remains unbound in the cytosol, making it unsuitable to monitor PLC signalling. Nonetheless, YFP-PH(PLCdelta1) is a valuable plant PtdIns(4,5)P(2) reporter, for it highlights specific cells and conditions where this lipid becomes abnormally concentrated in membranes, raising the question of what it is doing there. New roles for PtdIns(4,5)P(2) in plant cell signalling are discussed.
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Affiliation(s)
- Wessel van Leeuwen
- Section Plant Physiology, University of Amsterdam, Swammerdam Institute for Life Sciences, Kruislaan 318, NL-1098 SM, Amsterdam, The Netherlands
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312
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Peters NT, Logan KO, Miller AC, Kropf DL. Phospholipase D Signaling Regulates Microtubule Organization in the Fucoid Alga Silvetia compressa. ACTA ACUST UNITED AC 2007; 48:1764-74. [DOI: 10.1093/pcp/pcm149] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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313
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Larsson KE, Kjellberg JM, Tjellström H, Sandelius AS. LysoPC acyltransferase/PC transacylase activities in plant plasma membrane and plasma membrane-associated endoplasmic reticulum. BMC PLANT BIOLOGY 2007; 7:64. [PMID: 18045483 PMCID: PMC2241621 DOI: 10.1186/1471-2229-7-64] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Accepted: 11/28/2007] [Indexed: 05/02/2023]
Abstract
BACKGROUND The phospholipids of the plant plasma membrane are synthesized in the endoplasmic reticulum (ER). The majority of these lipids reach the plasma membrane independently of the secretory vesicular pathway. Phospholipid delivery to the mitochondria and chloroplasts of plant cells also bypasses the secretory pathway and here it has been proposed that lysophospholipids are transported at contact sites between specific regions of the ER and the respective organelle, followed by lysophospholipid acylation in the target organelle. To test the hypothesis that a corresponding mechanism operates to transport phospholipids to the plasma membrane outside the secretory pathway, we investigated whether lysolipid acylation occurs also in the plant plasma membrane and whether this membrane, like the chloroplasts and mitochondria, is in close contact with the ER. RESULTS The plant plasma membrane readily incorporated the acyl chain of acyl-CoA into phospholipids. Oleic acid was preferred over palmitic acid as substrate and acyl incorporation occurred predominantly into phosphatidylcholine (PC). Phospholipase A2 stimulated the reaction, as did exogenous lysoPC when administered in above critical micellar concentrations. AgNO3 was inhibitory. The lysophospholipid acylation reaction was higher in a membrane fraction that could be washed off the isolated plasma membranes after repeated freezing and thawing cycles in a medium with lowered pH. This fraction exhibited several ER-like characteristics. When plasma membranes isolated from transgenic Arabidopsis expressing green fluorescent protein in the ER lumen were observed by confocal microscopy, membranes of ER origin were associated with the isolated plasma membranes. CONCLUSION We conclude that a lysoPC acylation activity is associated with plant plasma membranes and cannot exclude a PC transacylase activity. It is highly plausible that the enzyme(s) resides in a fraction of the ER, closely associated with the plasma membrane, or in both. We suggest that this fraction might be the equivalent of the mitochondria associated membrane of ER origin that delivers phospholipids to the mitochondria, and to the recently isolated ER-derived membrane fraction that is in close contact with chloroplasts. The in situ function of the lysoPC acylation/PC transacylase activity is unknown, but involvement in lipid delivery from the ER to the plasma membrane is suggested.
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Affiliation(s)
- Karin E Larsson
- Department of Plant and Environmental Sciences, Göteborg University, P.O. Box 461, SE-405 30 Göteborg, Sweden
| | - J Magnus Kjellberg
- Department of Plant and Environmental Sciences, Göteborg University, P.O. Box 461, SE-405 30 Göteborg, Sweden
- Lead Discovery Informatics Team, Lead Generation Department, AstraZeneca R&D Mölndal, Sweden
| | - Henrik Tjellström
- Department of Plant and Environmental Sciences, Göteborg University, P.O. Box 461, SE-405 30 Göteborg, Sweden
| | - Anna Stina Sandelius
- Department of Plant and Environmental Sciences, Göteborg University, P.O. Box 461, SE-405 30 Göteborg, Sweden
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314
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Drissner D, Kunze G, Callewaert N, Gehrig P, Tamasloukht M, Boller T, Felix G, Amrhein N, Bucher M. Lyso-phosphatidylcholine is a signal in the arbuscular mycorrhizal symbiosis. Science 2007; 318:265-8. [PMID: 17932296 DOI: 10.1126/science.1146487] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The arbuscular mycorrhizal (AM) symbiosis represents the most widely distributed mutualistic root symbiosis. We report that root extracts of mycorrhizal plants contain a lipophilic signal capable of inducing the phosphate transporter genes StPT3 and StPT4 of potato (Solanum tuberosum L.), genes that are specifically induced in roots colonized by AM fungi. The same signal caused rapid extracellular alkalinization in suspension-cultured tomato (Solanum lycopersicum L.) cells and induction of the mycorrhiza-specific phosphate transporter gene LePT4 in these cells. The active principle was characterized as the lysolipid lyso-phosphatidylcholine (LPC) via a combination of gene expression studies, alkalinization assays in cell cultures, and chromatographic and mass spectrometric analyses. Our results highlight the importance of lysophospholipids as signals in plants and in particular in the AM symbiosis.
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Affiliation(s)
- David Drissner
- Institute of Plant Sciences, Eidgenössische Technische Hochschule (ETH) Zurich, Experimental Station Eschikon 33, 8315 Lindau, Switzerland
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315
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Torres-Franklin ML, Gigon A, de Melo DF, Zuily-Fodil Y, Pham-Thi AT. Drought stress and rehydration affect the balance between MGDG and DGDG synthesis in cowpea leaves. PHYSIOLOGIA PLANTARUM 2007; 131:201-10. [PMID: 18251892 DOI: 10.1111/j.1399-3054.2007.00943.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Membranes are main targets of drought, and there is growing evidence for the involvement of membrane lipid in plant adaptation to such an environmental stress. Biosynthesis of the galactosylglycerolipids, monogalactosyl-diacylglycerol (MGDG) and digalactosyl-diacylglycerol (DGDG), which are the main components of chloroplast envelope and thylakoid membranes, could be important for plant tolerance to water deficit and for recovery after rehydration. In this study, galactolipid (GL) biosynthesis in cowpea (Vigna unguiculata L. Walp) leaves was analysed during drought stress and subsequent rewatering. Comparison of two cowpea cutivars, one drought tolerant and the other drought susceptible submitted to moderate drought stress, revealed patterns associated with water-deficit tolerance: increase in DGDG leaf content, stimulation of DGDG biosynthesis in terms of (14)C-acetate incorporation and messenger accumulation corresponding to four genes coding for GL synthases (MDG1, MGD2, DGD1 and DGD2). Similar to phosphate starvation, lack of water enhanced DGDG biosynthesis and it was hypothesized that the drought-induced DGDG accumulated in extrachloroplastic membranes, and thus contributes to plant tolerance to arid environments.
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Affiliation(s)
- Maria-Lucia Torres-Franklin
- Laboratoire d'Ecophysiologie Moléculaire, UMR-IRD 137 BIOSOL, Université Paris XII -Val de Marne, 61 av. du Général de Gaulle, 94010 Créteil Cedex, France
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316
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Echevarría-Machado I, Martínez-Estévez M, Muñoz-Sánchez JA, Loyola-Vargas VM, Hernández-Sotomayor SMT, De Los Santos-Briones C. Membrane-associated phosphoinositides-specific phospholipase C forms from Catharanthus roseus transformed roots. Mol Biotechnol 2007; 35:297-309. [PMID: 17652793 DOI: 10.1007/bf02686015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 01/16/2023]
Abstract
We have previously reported that Catharanthus roseus transformed roots contain at least two phosphatidylinositol 4,5-bisphosphate-phospholipase C (PLC) activities, one soluble and the other membrane associated. Detergent, divalent cations, and neomycin differentially regulate these activities and pure protein is required for a greater understanding of the function and regulation of this enzyme. In this article we report a partia purification of membrane-associated PLC. We found that there are at least two forms of membraneassociated PLC in transformed roots of C. roseus. These forms were separated on the basis of their affinity for heparin. One form shows an affinity for heparin and elutes at approx 600 mM KCl. This form has a molecular mass of 67 kDa by size exclusion chromatography and Western blot analysis, whereas the other form does not bind to heparin and has a molecular mass of 57 kDa. Possible differential regulation of these forms during transformed root growth is discussed.
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Affiliation(s)
- Ileana Echevarría-Machado
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigaciòn Científica de Yucatán A.C., Calle 43 No. 130, Chuburná de Hidalgo, C. P. 97200, Mérida, Yucatán, México
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317
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Lokko Y, Anderson JV, Rudd S, Raji A, Horvath D, Mikel MA, Kim R, Liu L, Hernandez A, Dixon AGO, Ingelbrecht IL. Characterization of an 18,166 EST dataset for cassava (Manihot esculenta Crantz) enriched for drought-responsive genes. PLANT CELL REPORTS 2007; 26:1605-18. [PMID: 17541599 DOI: 10.1007/s00299-007-0378-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2007] [Revised: 05/03/2007] [Accepted: 05/04/2007] [Indexed: 05/15/2023]
Abstract
Cassava (Manihot esculenta Crantz) is a staple food for over 600 million people in the tropics and subtropics and is increasingly used as an industrial crop for starch production. Cassava has a high growth rate under optimal conditions but also performs well in drought-prone areas and on marginal soils. To increase the tools for understanding and manipulating drought tolerance in cassava, we generated expressed sequence tags (ESTs) from normalized cDNA libraries prepared from dehydration-stressed and control well-watered tissues. Analysis of a total of 18,166 ESTs resulted in the identification of 8,577 unique gene clusters (5,383 singletons and 3,194 clusters). Functional categories could be assigned to 63% of the unigenes, while another approximately 11% were homologous to hypothetical genes with unclear functions. The remaining approximately 26% were not significantly homologous to sequences in public databases suggesting that some may be novel and putatively specific to cassava. The dehydration-stressed library uncovered numerous ESTs with recognized roles in drought-responses, including those that encode late-embryogenesis-abundant proteins thought to confer osmoprotective functions during water stress, transcription factors, heat-shock proteins as well as proteins involved in signal transduction and oxidative stress. The unigene clusters were screened for short tandem repeats for further development as microsatellite markers. A total of 592 clusters contained 646 repeats, representing 3.3% of the ESTs queried. The ESTs presented here are the first dehydration stress transcriptome of cassava and can be utilized for the development of microarrays and gene-derived molecular markers to further dissect the molecular basis of drought tolerance in cassava.
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Affiliation(s)
- Y Lokko
- Central Biotechnology Laboratory, International Institute of Tropical Agriculture, Oyo Road, Ibadan, Nigeria
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318
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Pislariu CI, Dickstein R. The AGC Kinase MtIRE: A Link to Phospholipid Signaling During Nodulation? PLANT SIGNALING & BEHAVIOR 2007; 2:314-316. [PMID: 19704633 PMCID: PMC2634162 DOI: 10.4161/psb.2.4.4115] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2007] [Accepted: 03/07/2007] [Indexed: 05/28/2023]
Abstract
The development of nitrogen fixing root nodules is complex and involves an interplay of signaling processes. During maturation of plant host cells and their endocytosed rhizobia in symbiosomes, host cells and symbiosomes expand. This expansion is accompanied by a large quantity of membrane biogenesis. We recently characterized an AGC kinase gene, MtIRE, that could play a role in this expansion. MtIRE's expression coincides with host cell and symbiosome expansion in the proximal side of the invasion zone in developing Medicago truncatula nodules. MtIRE's closest homolog is the Arabidopsis AGC kinase family IRE gene, which regulates root hair elongation. AGC kinases are regulated by phospholipid signaling in animals and fungi as well as in the several instances where they have been studied in plants. Here we suggest that a phospholipid signaling pathway may also activate MtIRE activity and propose possible upstream activators of MtIRE protein's presumed AGC kinase activity.
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Affiliation(s)
- Catalina I Pislariu
- Department of Biological Sciences; University of North Texas; Denton, Texas USA
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319
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Laxalt AM, Raho N, Have AT, Lamattina L. Nitric Oxide Is Critical for Inducing Phosphatidic Acid Accumulation in Xylanase-elicited Tomato Cells. J Biol Chem 2007; 282:21160-8. [PMID: 17491015 DOI: 10.1074/jbc.m701212200] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Nitric Oxide (NO) is a second messenger related to development and (a)biotic stress responses in plants. We have studied the role of NO in signaling during plant defense responses upon xylanase elicitation. Treatment of tomato cell cultures with the fungal elicitor xylanase resulted in a rapid and dose-dependent NO accumulation. We have demonstrated that NO is required for the production of the lipid second messenger phosphatidic acid (PA) via the activation of the phospholipase C (PLC) and diacylglycerol kinase (DGK) pathway. Defense-related responses downstream of PA were studied. PA and, correspondingly, xylanase were shown to induce reactive oxygen species production. Scavenging of NO or inhibition of either the PLC or the DGK enzyme diminished xylanase-induced reactive oxygen species production. Xylanase-induced PLDbeta1 and PR1 mRNA levels decreased when NO or PA production were compromised. Finally, we have shown that NO and PA are involved in the induction of cell death by xylanase. Treatment with NO scavenger cPTIO, PLC inhibitor U73122, or DGK inhibitor R59022 diminished xylanase-induced cell death. On the basis of biochemical and pharmacological experimental results, we have shown that PLC/DGK-derived PA represents a novel downstream component of NO signaling cascade during plant defense.
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Affiliation(s)
- Ana M Laxalt
- Instituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata, CC 1245, 7600 Mar del Plata, Argentina.
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320
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Leshem Y, Seri L, Levine A. Induction of phosphatidylinositol 3-kinase-mediated endocytosis by salt stress leads to intracellular production of reactive oxygen species and salt tolerance. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 51:185-97. [PMID: 17521408 DOI: 10.1111/j.1365-313x.2007.03134.x] [Citation(s) in RCA: 175] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Salt imposes immediate problems for plant cells, such as osmotic stress, impaired ion homeostasis and sodium toxicity, followed by a secondary oxidative stress caused by generation of reactive oxygen species (ROS). Here, we analyzed the production of ROS during salt stress. We show that salt stress triggered plasma membrane internalization, resulting in the production of ROS within endosomes. The intracellular ROS were produced by NADPH oxidase in response to the ionic but not the osmotic stress. Both endocytosis and ROS production were suppressed in phosphatidylinositol (PtdIns) 3-kinase (PI3K) mutants, PI3K being a key regulator of vesicle trafficking in animals and plants, and by wortmannin, which is a specific inhibitor of PI3K and PI4K. Endocytosis and the production of ROS were rescued by supplementation of seedlings with exogenous PtdIns 3-phosphate (PtdIns3P), less with PtdIns4P, but not with PtdIns(4,5)P(2). Surprisingly, despite reduced oxidative stress, the mutants and the wortmannin-treated plants exhibited a phenotype overly sensitive to salt, as also resulted from treatment with diphenyleneiodonium, a suicide inhibitor of NADPH oxidase, suggesting a positive role for ROS in salt tolerance. In summary, our results show that salt stress responses, such as increased plasma membrane endocytosis and the intracellular production of ROS, are coordinated by phospholipid-regulated signaling pathways, and suggest that ROS act in the signal transduction of the salt tolerance response.
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Affiliation(s)
- Yehoram Leshem
- Department of Plant Sciences, Institute of Life Sciences, The Hebrew University of Jerusalem, Givat-Ram, Jerusalem, Israel
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321
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Krinke O, Ruelland E, Valentová O, Vergnolle C, Renou JP, Taconnat L, Flemr M, Burketová L, Zachowski A. Phosphatidylinositol 4-kinase activation is an early response to salicylic acid in Arabidopsis suspension cells. PLANT PHYSIOLOGY 2007; 144:1347-59. [PMID: 17496105 PMCID: PMC1914138 DOI: 10.1104/pp.107.100842] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Salicylic acid (SA) has a central role in defense against pathogen attack. In addition, its role in such diverse processes as germination, flowering, senescence, and thermotolerance acquisition has been documented. However, little is known about the early signaling events triggered by SA. Using Arabidopsis (Arabidopsis thaliana) suspension cells as a model, it was possible to show by in vivo metabolic phospholipid labeling with (33)P(i) that SA addition induced a rapid and early (in few minutes) decrease in a pool of phosphatidylinositol (PI). This decrease paralleled an increase in PI 4-phosphate and PI 4,5-bisphosphate. These changes could be inhibited by two different inhibitors of type III PI 4-kinases, phenylarsine oxide and 30 microm wortmannin; no inhibitory effect was seen with 1 microm wortmannin, a concentration inhibiting PI 3-kinases but not PI 4-kinases. We therefore undertook a study of the effects of wortmannin on SA-responsive transcriptomes. Using the Complete Arabidopsis Transcriptome MicroArray chip, we could identify 774 genes differentially expressed upon SA treatment. Strikingly, among these genes, the response to SA of 112 of them was inhibited by 30 microm wortmannin, but not by 1 microm wortmannin.
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Affiliation(s)
- Ondrej Krinke
- Université Pierre et Marie Curie-Paris 6 and Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7180, Laboratoire de Physiologie Cellulaire et Moléculaire des Plantes, Ivry-sur-Seine, France.
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322
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Abstract
Many stimuli induce short-term increases in the cytosolic concentration of free calcium ions ([Ca(2+)](i)) that encode signaling information about diverse physiological and developmental events. Slow cytosolic Ca(2+) oscillations that span an entire day have also been discovered in both plants and animals; it is thought that these daily Ca(2+) oscillations may encode circadian clock signaling information. A recent study focusing on the characterization of the extracellular Ca(2+)-sensing receptor (CAS) has provided insight into the molecular mechanisms by which the daily Ca(2+) oscillation in plants is generated. We summarize the major findings regarding daily oscillations of cytosolic Ca(2+) concentrations in plants and animals, and discuss hypothetical biological roles for the circadian clock-regulated physiology in plants.
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Affiliation(s)
- Takato Imaizumi
- Department of Biochemistry, Scripps Research Institute, La Jolla, CA 92037, USA.
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323
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Im YJ, Perera IY, Brglez I, Davis AJ, Stevenson-Paulik J, Phillippy BQ, Johannes E, Allen NS, Boss WF. Increasing plasma membrane phosphatidylinositol(4,5)bisphosphate biosynthesis increases phosphoinositide metabolism in Nicotiana tabacum. THE PLANT CELL 2007; 19:1603-16. [PMID: 17496116 PMCID: PMC1913725 DOI: 10.1105/tpc.107.051367] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2007] [Revised: 04/18/2007] [Accepted: 04/23/2007] [Indexed: 05/15/2023]
Abstract
A genetic approach was used to increase phosphatidylinositol(4,5)bisphosphate [PtdIns(4,5)P2] biosynthesis and test the hypothesis that PtdInsP kinase (PIPK) is flux limiting in the plant phosphoinositide (PI) pathway. Expressing human PIPKIalpha in tobacco (Nicotiana tabacum) cells increased plasma membrane PtdIns(4,5)P2 100-fold. In vivo studies revealed that the rate of 32Pi incorporation into whole-cell PtdIns(4,5)P2 increased >12-fold, and the ratio of [3H]PtdInsP2 to [3H]PtdInsP increased 6-fold, but PtdInsP levels did not decrease, indicating that PtdInsP biosynthesis was not limiting. Both [3H]inositol trisphosphate and [3H]inositol hexakisphosphate increased 3-and 1.5-fold, respectively, in the transgenic lines after 18 h of labeling. The inositol(1,4,5)trisphosphate [Ins(1,4,5)P3] binding assay showed that total cellular Ins(1,4,5)P3/g fresh weight was >40-fold higher in transgenic tobacco lines; however, even with this high steady state level of Ins(1,4,5)P3, the pathway was not saturated. Stimulating transgenic cells with hyperosmotic stress led to another 2-fold increase, suggesting that the transgenic cells were in a constant state of PI stimulation. Furthermore, expressing Hs PIPKIalpha increased sugar use and oxygen uptake. Our results demonstrate that PIPK is flux limiting and that this high rate of PI metabolism increased the energy demands in these cells.
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Affiliation(s)
- Yang Ju Im
- Department of Plant Biology, North Carolina State University, Raleigh, North Carolina 27695, USA
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324
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Yip HSH, Ashraf-Khorassani M, Taylor LT. Feasibility of Phospholipids Separation by Packed Column SFC with Mass Spectrometric and Light Scattering Detection. Chromatographia 2007. [DOI: 10.1365/s10337-007-0235-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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325
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Tang RH, Han S, Zheng H, Cook CW, Choi CS, Woerner TE, Jackson RB, Pei ZM. Coupling diurnal cytosolic Ca2+ oscillations to the CAS-IP3 pathway in Arabidopsis. Science 2007; 315:1423-6. [PMID: 17347443 DOI: 10.1126/science.1134457] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Various signaling pathways rely on changes in cytosolic calcium ion concentration ([Ca2+]i). In plants, resting [Ca2+]i oscillates diurnally. We show that in Arabidopsis thaliana, [Ca2+]i oscillations are synchronized to extracellular Ca2+ concentration ([Ca2+]o) oscillations largely through the Ca2+-sensing receptor CAS. CAS regulates concentrations of inositol 1,4,5-trisphosphate (IP3), which in turn directs release of Ca2+ from internal stores. The oscillating amplitudes of [Ca2+]o and [Ca2+]i are controlled by soil Ca2+ concentrations and transpiration rates. The phase and period of oscillations are likely determined by stomatal conductance. Thus, the internal concentration of Ca2+ in plant cells is constantly being actively revised.
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Affiliation(s)
- Ru-Hang Tang
- Department of Biology, Duke University, Durham, NC 27708, USA
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326
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Domingues SJ, Souza TFD, Soares AM, Jacinto T, Machado OL. Activation of phospholipase PLA2 actvity in Ricinus communis leaves in response to mechanical wounding. ACTA ACUST UNITED AC 2007. [DOI: 10.1590/s1677-04202007000100004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In order to investigate the defense response in castor bean (Ricinus communis) against predators, we analyzed the effect of mechanical wounding upon the phospholipase A2 (PLA2) activity of leaf extracts. Time course experiments revealed that the highest levels of increased PLA2 activity (ca. two fold) occurred 15 min and 60 min after injury. The induced activities demonstrated high sensitivity towards aristolochic acid (10 mM), a PLA2 inhibitor. Based on SDS-PAGE analysis, the PLA2 activity induced 15 min after wounding migrated with a molecular mass of 40 kDa and was denoted RcPLA2 I. The protein activity induced 60 min after wounding, RcPLA2 II, migrated with a molecular weight of 14 kDa. Furthermore its N-terminal sequence shared homology with PLA2 from elm and rice. The PLA2 enzymes were purified to near homogeneity by a combination of gel filtration and electro-elution of protein bands after native PAGE.
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327
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Fujiki Y, Yoshimoto K, Ohsumi Y. An Arabidopsis homolog of yeast ATG6/VPS30 is essential for pollen germination. PLANT PHYSIOLOGY 2007; 143:1132-9. [PMID: 17259285 PMCID: PMC1820928 DOI: 10.1104/pp.106.093864] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Yeast (Saccharomyces cerevisiae) Atg6/Vps30 is required for autophagy and the sorting of vacuolar hydrolases, such as carboxypeptidase Y. In higher eukaryotes, however, roles for ATG6/VPS30 homologs in vesicle sorting have remained obscure. Here, we show that AtATG6, an Arabidopsis (Arabidopsis thaliana) homolog of yeast ATG6/VPS30, restored both autophagy and vacuolar sorting of carboxypeptidase Y in a yeast atg6/vps30 mutant. In Arabidopsis cells, green fluorescent protein-AtAtg6 protein localized to punctate structures and colocalized with AtAtg8, a marker protein of the preautophagosomal structure. Disruption of AtATG6 by T-DNA insertion resulted in male sterility that was confirmed by reciprocal crossing experiments. Microscopic analyses of AtATG6 heterozygous plants (AtATG6/atatg6) crossed with the quartet mutant revealed that AtATG6-deficient pollen developed normally, but did not germinate. Because other atatg mutants are fertile, AtAtg6 likely mediates pollen germination in a manner independent of autophagy. We propose that Arabidopsis Atg6/Vps30 functions not only in autophagy, but also plays a pivotal role in pollen germination.
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Affiliation(s)
- Yuki Fujiki
- Department of Cell Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan
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328
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König S, Mosblech A, Heilmann I. Stress-inducible and constitutive phosphoinositide pools have distinctive fatty acid patterns in Arabidopsis thaliana. FASEB J 2007; 21:1958-67. [PMID: 17327357 DOI: 10.1096/fj.06-7887com] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Function and development of eukaryotic cells require tight control of diverse physiological processes. Numerous cellular processes are regulated by polyphosphoinositides, which interact with protein partners or mediate release of the second messenger, inositol 1,4,5-trisphosphate (InsP3). Emerging evidence suggests that different regulatory or signaling functions of polyphosphoinositides may be orchestrated by the establishment of distinct subcellular pools; the principles underlying pool-formation are, however, not understood. Arabidopsis plants exhibit transient increases in polyphosphoinositides with hyperosmotic stress, providing a model for comparing constitutive and stress-inducible polyphosphoinositide pools. Using a combination of thin-layer-chromatography and gas-chromatography, phospholipids from stressed and nonstressed Arabidopsis plants were analyzed for their associated fatty acids. Under nonstress conditions structural phospholipids and phosphatidylinositol contained 50-70 mol% polyunsaturated fatty acids (PUFA), whereas polyphosphoinositides were more saturated (10-20 mol% PUFA). With hyperosmotic stress polyphosphoinositides with up to 70 mol% PUFA were formed that differed from constitutive species and coincided with a transient loss in unsaturated phosphatidylinositol. The patterns indicate inducible turnover of an unsaturated phosphatidylinositol pool, which accumulates under standard conditions and is primed for phosphorylation on stimulation. Metabolic analysis of wild-type and transgenic plants disturbed in phosphoinositide metabolism suggests that, in contrast to saturated species, unsaturated polyphosphoinositides are channeled toward InsP3-production.
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Affiliation(s)
- Sabine König
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
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329
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Im YJ, Davis AJ, Perera IY, Johannes E, Allen NS, Boss WF. The N-terminal membrane occupation and recognition nexus domain of Arabidopsis phosphatidylinositol phosphate kinase 1 regulates enzyme activity. J Biol Chem 2007; 282:5443-52. [PMID: 17197438 DOI: 10.1074/jbc.m611342200] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The type I B family of phosphatidylinositol phosphate kinases (PIPKs) contain a characteristic region of Membrane Occupation and Recognition Nexus (MORN) motifs at the N terminus. These MORN motifs are not found in PIPKs from other eukaryotes. To understand the impact of the additional N-terminal domain on protein function and subcellular distribution, we expressed truncated and full-length versions of AtPIPK1, one member of this family of PIPKs, in Escherichia coli and in tobacco cells grown in suspension culture. Deletion of the N-terminal MORN domain (amino acids 1-251) of AtPIPK1 increased the specific activity of the remaining C-terminal peptide (DeltaMORN) >4-fold and eliminated activation by phosphatidic acid (PtdOH). PtdOH activation could also be eliminated by mutating Pro(396) to Ala (P396A) in the predicted linker region between the MORN and the kinase homology domains. AtPIPK1 is product-activated and the MORN domain binds PtdIns(4,5)P(2). Adding back the MORN peptide to DeltaMORN or to the PtdOH-activated full-length protein increased activity approximately 2-fold. Furthermore, expressing the MORN domain in vivo increased the plasma membrane PtdInsP kinase activity. When cells were exposed to hyperosmotic stress, the MORN peptide redistributed from the plasma membrane to a lower phase or endomembrane fraction. In addition, endogenous PtdInsP kinase activity increased in the endomembrane fraction of hyperosmotically stressed cells. We conclude that the MORN peptide can regulate both the function and distribution of the enzyme in a manner that is sensitive to the lipid environment.
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Affiliation(s)
- Yang Ju Im
- Plant Biology, North Carolina State University, Raleigh, North Carolina 27695-7649, USA
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330
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Quintal-Tun F, Muñoz-Sánchez JA, Ramos-Díaz A, Escamilla-Bencomo A, Martínez-Estévez M, Exley C, Hernández-Sotomayor SMT. Aluminium-induced phospholipid signal transduction pathway in Coffea arabica suspension cells and its amelioration by silicic acid. J Inorg Biochem 2007; 101:362-9. [PMID: 17161461 DOI: 10.1016/j.jinorgbio.2006.10.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2006] [Revised: 10/20/2006] [Accepted: 10/27/2006] [Indexed: 11/23/2022]
Abstract
Coffee (Coffea arabica L.) is of economic importance worldwide. Its growth in organic-rich acidic soils is influenced by aluminium such that coffee yield may be impaired. Herein we have used the Al-sensitive C. arabica suspension cell line L2 to analyse the effect of two different Al species on the phosphoinositide signal transduction pathway. Our results have shown that the association of Al with coffee cells was affected by the pH and the form of Al in media. More Al was associated with cells at pH 4.3 than 5.8, whereas when Al was present as hydroxyaluminosilicates (HAS) the association was halved at pH 4.3 and unchanged at pH 5.8. Two signal transduction elements were also evaluated; phospholipase C (PLC) activity and phosphatidic acid (PA) formation. PLC was inhibited ( approximately 50%) when cells were incubated for 2 h in the presence of either AlCl(3) or Al in the form of HAS. PA formation was tested as a short-term response to Al. By way of contrast to what was found for PLC, incubation of cells for 15 min in the presence of AlCl(3) decreased the formation of PA whereas the same concentration of Al as HAS produced no effect upon its formation. These results suggest that Al is capable to exert its effects upon signal transduction as Al((aq))(3+) acting upon a mechanism linked to the phosphoinositide signal transduction pathway.
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Affiliation(s)
- Fausto Quintal-Tun
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán, Calle 43, No. 130, Chuburná de Hidalgo, C.P. 97200 Mérida, Yucatán, Mexico
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331
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Abstract
Phosphatidic acid (PA) is emerging as a key phospholipid in a wide range of biological processes such as signal transduction, secretion, or membrane fusion. In most cases, the biological functionality of PA is associated with the presence of micromolar to millimolar calcium concentrations. It has been argued that PA can create defects in the packing of lipids in membranes due to lateral phase separation by divalent ions, which in turn aggregate proteins with high affinity for PA. In this article, we present a detailed investigation of the properties of PA domains in the presence of divalent ions by a combination of molecular dynamics simulations and theoretical methods. Our results show that PA is extremely effective in binding divalent ions through its oxygen atoms, with a broad distribution of binding constants and exhibiting the phenomenon of charge inversion (a total number of bound counterion charges that exceeds the negative PA charge). We predict that a PA-rich domain undergoes a drastic reorganization when divalent cations reach micromolar concentrations (i.e., typical physiological conditions), as PA lipids become doubly charged by releasing their protons. We also present a detailed investigation of the properties of interfacial water, which determine the binding of proteins or other molecules. We conclude with a discussion of the implications of our results in the context of recent experimental studies in model systems and in real cells.
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Affiliation(s)
- Jordi Faraudo
- Departament de Fisica, Universitat Autonoma de Barcelona, Bellaterra, Spain.
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332
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Guidetti-Gonzalez S, Freitas-Astúa J, Amaral AMD, Martins NF, Mehta A, Silva MS, Carrer H. Genes associated with hypersensitive response (HR) in the citrus EST database (CitEST). Genet Mol Biol 2007. [DOI: 10.1590/s1415-47572007000500022] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
| | - Juliana Freitas-Astúa
- Embrapa Mandioca e Fruticultura Tropical, Brazil; Instituto Agronômico de Campinas, Brazil
| | | | | | - Angela Mehta
- Embrapa Recursos Genéticos e Biotecnologia, Brazil
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333
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Jouhet J, Maréchal E, Block MA. Glycerolipid transfer for the building of membranes in plant cells. Prog Lipid Res 2007; 46:37-55. [PMID: 16970991 DOI: 10.1016/j.plipres.2006.06.002] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2006] [Revised: 06/14/2006] [Accepted: 06/20/2006] [Indexed: 01/05/2023]
Abstract
Membranes of plant organelles have specific glycerolipid compositions. Selective distribution of lipids at the levels of subcellular organelles, membrane leaflets and membrane domains reflects a complex and finely tuned lipid homeostasis. Glycerolipid neosynthesis occurs mainly in plastid envelope and endoplasmic reticulum membranes. Since most lipids are not only present in the membranes where they are synthesized, one cannot explain membrane specific lipid distribution by metabolic processes confined in each membrane compartment. In this review, we present our current understanding of glycerolipid trafficking in plant cells. We examine the potential mechanisms involved in lipid transport inside bilayers and from one membrane to another. We survey lipid transfers going through vesicular membrane flow and those dependent on lipid transfer proteins at membrane contact sites. By introducing recently described membrane lipid reorganization during phosphate deprivation and recent developments issued from mutant analyses, we detail the specific lipid transfers towards or outwards the chloroplast envelope.
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Affiliation(s)
- Juliette Jouhet
- Laboratoire de Physiologie, Cellulaire Végétale, UMR 5168 (CNRS/CEA/Université Joseph Fourier/INRA), DRDC/PCV, CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble-cedex 9, France
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334
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Johnston MK, Jacob NP, Brodl MR. Heat shock-induced changes in lipid and protein metabolism in the endoplasmic reticulum of barley aleurone layers. PLANT & CELL PHYSIOLOGY 2007; 48:31-41. [PMID: 17118946 DOI: 10.1093/pcp/pcl037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Heat shock in barley aleurone layers induces heat shock protein synthesis and suppresses secretory protein synthesis by selectively destabilizing their mRNAs. In addition, the endoplasmic reticulum (ER) membranes upon which secretory protein mRNAs are translated become vesiculated during heat shock, leading to the hypothesis that ER dissociation and targeted mRNA destabilization are linked mechanistically. Supporting this, ER can be heat adapted, and heat-adapted ER has higher levels of fatty acid saturation in membrane phospholipids which do not vesiculate upon heat shock. Secretory protein mRNAs are also more stable in heat-adapted cells. To understand better heat shock-induced changes in ER membranes, we examined ER membrane proteins and enzymes involved in phosphatidylcholine biosynthesis and phospholipid turnover in heat-shocked aleurone cells. Heat shock significantly increased the activity of phospholipases A2 and D, and shortly thereafter significant but gradual increases in choline kinase and phosphocholine glyceride transferase activities and a sharp increase in phosphorylcholine citidyl transferase activity were observed. Only minor changes were observed in SDS-PAGE analyses of proteins from sonicated ER membranes fractionated on continuous sucrose gradients. Overall, heat shock reduced total lipid in ER membranes relative to protein, and in intact, ultracentrifuged aleurone cells examined by light and electron microscopy the ER band appeared to increase in density. The changes in phospholipid metabolism coupled with the suppression of secretory protein synthesis indicate that in addition to inducing a classic heat shock response, high temperature also induces a classic unfolded protein response in the ER of this secretory cell.
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Affiliation(s)
- Mark K Johnston
- Department of Biology, Knox College, Galesburg, IL 61401, USA
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335
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Chen J, Zhang W, Song F, Zheng Z. Phospholipase C/diacylglycerol kinase-mediated signalling is required for benzothiadiazole-induced oxidative burst and hypersensitive cell death in rice suspension-cultured cells. PROTOPLASMA 2007; 230:13-21. [PMID: 17111096 DOI: 10.1007/s00709-006-0195-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Accepted: 03/22/2006] [Indexed: 05/07/2023]
Abstract
The involvement of phospholipase C/diacylglycerol kinase (PLC/DGK)-mediated signalling in oxidative burst and hypersensitive cell death was studied in rice suspension-cultured cells treated with benzothiadiazole (BTH) and infected by Xanthomonas oryza pv. oryza (Xoo), the causal agent of rice leaf blight disease. Treatment of rice suspension cells with BTH resulted in a significant oxidative burst, as indicated by accumulation of superoxide anion and H(2)O(2), and hypersensitive cell death, as determined by Evans blue staining. A peak in oxidative burst was detected 3-4 h after BTH treatment and hypersensitive cell death was observed 8 h after treatment. In addition, significant oxidative burst and hypersensitive cell death were detected in BTH-treated suspension cells, but not in untreated control cells, after Xoo infection. Scavengers and antioxidants of active oxygen species, e.g., superoxide dismutase, catalase, N-acetylcysteine, and flavone, reduced significantly the BTH-induced oxidative burst and hypersensitive cell death, indicating that oxidative burst is required for BTH-induced hypersensitive cell death. Expression of the PLC/DGK pathway genes, a diacylglycerol kinase gene, OsDAGK1, and a phosphoinositide-specific phospholipase C gene, OsPI-PLC1, and a defence-related EREBP transcriptional factor gene, OsBIERF3, was activated in rice cells after BTH treatment and in the BTH-treated cells after Xoo infection. Treatment of rice cells with phosphatidic acid, a phospholipid signalling molecule, resulted in the production of oxidative burst and hypersensitive cell death. However, neomycin, a PLC inhibitor, inhibited partially but not completely the production of oxidative burst, hypersensitive cell death, and expression of OsBIERF3 and OsDAGK1 induced by BTH in rice cells. These results suggest that PLC/DGK-mediated signalling plays an important role in BTH-induced oxidative burst, hypersensitive response, and activation of defence response in rice.
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Affiliation(s)
- Jie Chen
- Institute of Biotechnology, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, Zhejiang
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336
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Tittarelli A, Milla L, Vargas F, Morales A, Neupert C, Meisel LA, Salvo-G H, Peñaloza E, Muñoz G, Corcuera LJ, Silva H. Isolation and comparative analysis of the wheat TaPT2 promoter: identification in silico of new putative regulatory motifs conserved between monocots and dicots. JOURNAL OF EXPERIMENTAL BOTANY 2007; 58:2573-82. [PMID: 17562688 DOI: 10.1093/jxb/erm123] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Phosphorus deficiency is one of the major nutrient stresses affecting plant growth. Plants respond to phosphate (Pi) deficiency through multiple strategies, including the synthesis of high-affinity Pi transporters. In this study, the expression pattern of one putative wheat high-affinity phosphate transporter, TaPT2, was examined in roots and leaves under Pi-deficient conditions. TaPT2 transcript levels increased in roots of Pi-starved plants. A 579 bp fragment of the TaPT2 promoter is sufficient to drive the expression of the GUS reporter gene specifically in roots of Pi-deprived wheat. This TaPT2 promoter fragment was also able to drive expression of the GUS reporter gene in transgenic Arabidopsis thaliana, under similar growth conditions. Conserved regions and candidate regulatory motifs were detected by comparing this promoter with Pi transporter promoters from barley, rice, and Arabidopsis. Altogether, these results indicate that there are conserved cis-acting elements and trans-acting factors that enable the TaPT2 promoter to be regulated in a tissue-specific and Pi-dependent fashion in both monocots and dicots.
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Affiliation(s)
- A Tittarelli
- Millennium Nucleus in Plant Cell Biology and Center of Plant Biotechnology, Andres Bello University, Av República 217, 837-0146, Santiago, Chile
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337
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Boss WF, Davis AJ, Im YJ, Galvão RM, Perera IY. Phosphoinositide metabolism: towards an understanding of subcellular signaling. Subcell Biochem 2006; 39:181-205. [PMID: 17121276 DOI: 10.1007/0-387-27600-9_8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- Wendy F Boss
- Department of Plant Biology, North Carolina State University, Raleigh, NC 27695-7612, USA
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338
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Hofius D, Tsitsigiannis DI, Jones JDG, Mundy J. Inducible cell death in plant immunity. Semin Cancer Biol 2006; 17:166-87. [PMID: 17218111 DOI: 10.1016/j.semcancer.2006.12.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Accepted: 12/02/2006] [Indexed: 01/06/2023]
Abstract
Programmed cell death (PCD) occurs during vegetative and reproductive plant growth, as typified by autumnal leaf senescence and the terminal differentiation of the endosperm of cereals which provide our major source of food. PCD also occurs in response to environmental stress and pathogen attack, and these inducible PCD forms are intensively studied due their experimental tractability. In general, evidence exists for plant cell death pathways which have similarities to the apoptotic, autophagic and necrotic forms described in yeast and metazoans. Recent research aiming to understand these pathways and their molecular components in plants are reviewed here.
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Affiliation(s)
- Daniel Hofius
- Department of Molecular Biology, University of Copenhagen, Øster Farimagsgade 2A, 1353 Copenhagen K, Denmark
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339
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Helling D, Possart A, Cottier S, Klahre U, Kost B. Pollen tube tip growth depends on plasma membrane polarization mediated by tobacco PLC3 activity and endocytic membrane recycling. THE PLANT CELL 2006; 18:3519-34. [PMID: 17172355 PMCID: PMC1785407 DOI: 10.1105/tpc.106.047373] [Citation(s) in RCA: 189] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2006] [Revised: 09/13/2006] [Accepted: 11/06/2006] [Indexed: 05/13/2023]
Abstract
Phosphatidyl inositol 4,5-bisphosphate (PI 4,5-P2) accumulates in a Rac/Rop-dependent manner in the pollen tube tip plasma membrane, where it may control actin organization and membrane traffic. PI 4,5-P2 is hydrolyzed by phospholipase C (PLC) activity to the signaling molecules inositol 1,4,5-trisphosphate and diacyl glycerol (DAG). To investigate PLC activity during tip growth, we cloned Nt PLC3, specifically expressed in tobacco (Nicotiana tabacum) pollen tubes. Recombinant Nt PLC3 displayed Ca2+-dependent PI 4,5-P2-hydrolyzing activity sensitive to U-73122 and to mutations in the active site. Nt PLC3 overexpression, but not that of inactive mutants, inhibited pollen tube growth. Yellow fluorescent protein (YFP) fused to Nt PLC3, or to its EF and C2 domains, accumulated laterally at the pollen tube tip plasma membrane in a pattern complementary to the distribution of PI 4,5-P2. The DAG marker Cys1:YFP displayed a similar intracellular localization as PI 4,5-P2. Blocking endocytic membrane recycling affected the intracellular distribution of DAG but not of PI 4,5-P2. U-73122 at low micromolar concentrations inhibited and partially depolarized pollen tube growth, caused PI 4,5-P2 spreading at the apex, and abolished DAG membrane accumulation. We show that Nt PLC3 is targeted by its EF and C2 domains to the plasma membrane laterally at the pollen tube tip and that it maintains, together with endocytic membrane recycling, an apical domain enriched in PI 4,5-P2 and DAG required for polar cell growth.
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Affiliation(s)
- Diana Helling
- Heidelberg Institute of Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany
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340
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Kriegs B, Theisen R, Schnabl H. Inositol 1,4,5-trisphosphate and Ran expression during simulated and real microgravity. PROTOPLASMA 2006; 229:163-74. [PMID: 17180498 DOI: 10.1007/s00709-006-0214-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2005] [Accepted: 01/10/2006] [Indexed: 05/13/2023]
Abstract
In order to gain further insight into the signal transduction pathway concerning gravitropism, we studied the expression profiles of mRNA in etiolated sunflower (Helianthus annuus L.) seedlings. Differential-display reverse transcriptase PCR product assayed by capillary electrophoresis revealed the small GTPase Ran, regulating nuclear import and export of proteins. Parallel analysis of inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) release by a highly advanced system of metal-dye detection combined with high-performance liquid chromatography provided evidence that the second messenger Ins(1,4,5)P3 is modulated by changes of the gravity vector. Investigations by fast clinorotation and sounding rockets established a positive correlation between the Ins(1,4,5)P3 level and the expression rate of Ran mRNA during simulated and real microgravity. Since an asymmetric distribution of auxin during graviresponse is suggested to induce differential cell elongation, additional information on the perception and transduction pathways was achieved by auxin stimulation experiments. While we were able to demonstrate an auxin-dependent production of Ins(1,4,5)P3, the expression of Ran mRNA was not affected by auxin. Finally, besides the phosphoinositide system as one element of the signal transduction chain linking graviperception to graviresponse, a Ran-mediated interaction model of extracellular microgravity signal perception and intercellular transduction pathway is proposed.
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Affiliation(s)
- B Kriegs
- Institute for Molecular Physiology and Biotechnology of Plants, University of Bonn, Bonn, Federal Republic of Germany
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341
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Meijer HJG, Govers F. Genomewide analysis of phospholipid signaling genes in Phytophthora spp.: novelties and a missing link. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2006; 19:1337-47. [PMID: 17153918 DOI: 10.1094/mpmi-19-1337] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Phospholipids are cellular membrane components in eukaryotic cells that execute many important roles in signaling. Genes encoding enzymes required for phospholipid signaling and metabolism have been characterized in several organisms, but only a few have been described for oomycetes. In this study, the genome sequences of Phytophthora sojae and P. ramorum were explored to construct a comprehensive genomewide inventory of genes involved in the most universal phospholipid signaling pathways. Several genes and gene families were annotated, including those encoding phosphatidylinositol synthase (PIS), phosphatidylinositol (phosphate) kinase (PI[P]K), diacylglycerol kinase (DAG), and phospholipase D (PLD). The most obvious missing link is a gene encoding phospholipase C (PLC). In all eukaryotic genomes sequenced to date, PLC genes are annotated based on certain conserved features; however, these genes seem to be absent in Phytophthora spp. Analysis of the structural and regulatory domains and domain organization of the predicted isoforms of PIS, PIK, PIPK, DAG, and PLD revealed many novel features compared with characterized representatives in other eukaryotes. Examples are transmembrane proteins with a C-terminal catalytic PLD domain, secreted PLD-like proteins, and PIPKs that have an N-terminal G-protein-coupled receptor-transmembrane signature. Compared with other sequenced eukaryotes, the genus Phytophthora clearly has several exceptional features in its phospholipid-modifying enzymes.
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Affiliation(s)
- Harold J G Meijer
- Laboratory of Phytopathology, Plant Sciences Group, Wageningen University, Binnenhaven 5, NL-6709 PD Wageningen, The Netherlands.
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342
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Gechev TS, Van Breusegem F, Stone JM, Denev I, Laloi C. Reactive oxygen species as signals that modulate plant stress responses and programmed cell death. Bioessays 2006; 28:1091-101. [PMID: 17041898 DOI: 10.1002/bies.20493] [Citation(s) in RCA: 558] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Reactive oxygen species (ROS) are known as toxic metabolic products in plants and other aerobic organisms. An elaborate and highly redundant plant ROS network, composed of antioxidant enzymes, antioxidants and ROS-producing enzymes, is responsible for maintaining ROS levels under tight control. This allows ROS to serve as signaling molecules that coordinate an astonishing range of diverse plant processes. The specificity of the biological response to ROS depends on the chemical identity of ROS, intensity of the signal, sites of production, plant developmental stage, previous stresses encountered and interactions with other signaling molecules such as nitric oxide, lipid messengers and plant hormones. Although many components of the ROS signaling network have recently been identified, the challenge remains to understand how ROS-derived signals are integrated to eventually regulate such biological processes as plant growth, development, stress adaptation and programmed cell death.
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343
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Amiri A, Noei F, Jeganathan S, Kulkarni G, Pinke DE, Lee JM. eEF1A2 activates Akt and stimulates Akt-dependent actin remodeling, invasion and migration. Oncogene 2006; 26:3027-40. [PMID: 17130842 DOI: 10.1038/sj.onc.1210101] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
eEF1A2 (eukaryotic protein elongation factor 1 alpha 2) is a protein translation factor that is likely a human oncogene by virtue of its capacity to transform mammalian cells and its high expression in tumors of the ovary, breast and lung. Here, we show that expression of eEF1A2 is sufficient to stimulate the formation of filopodia in BT549 human breast cancer cells and non-transformed Rat2 cells. Filopodia formation in eEF1A2-expressing cells is dependent on the activity of phosphatidylinositol-3 kinase (PI3K), and the ROCK and Akt kinases. Furthermore, eEF1A2 expression is sufficient to activate Akt in a PI3K-dependent fashion and inactivation of eEF1A2 by short interfering RNA reduces Akt activity. Using breast cancer cell line BT 549, we show that eEF1A2 expression stimulates cell migration and invasion in a largely PI3K- and Akt-dependent manner. These results suggest that eEF1A2 regulates oncogenesis through Akt and PI3K-dependent cytoskeletal remodeling.
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Affiliation(s)
- A Amiri
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
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344
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Jeganathan S, Lee JM. Binding of elongation factor eEF1A2 to phosphatidylinositol 4-kinase beta stimulates lipid kinase activity and phosphatidylinositol 4-phosphate generation. J Biol Chem 2006; 282:372-80. [PMID: 17088255 DOI: 10.1074/jbc.m602955200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Eukaryotic protein translation elongation factor 1 alpha 2 (eEF1A2) is an oncogene that transforms mammalian cell lines and increases their tumorigenicity in nude mice. Increased expression of eEF1A2 occurs during the development of breast, ovarian, and lung cancer. Here, we report that eEF1A2 directly binds to and activates phosphatidylinositol 4-kinase III beta (PI4KIIIbeta), an enzyme that converts phosphatidylinositol to phosphatidylinositol 4-phosphate. Purified recombinant eEF1A2 increases PI4KIIIbeta lipid kinase activity in vitro, and expression of eEF1A2 in rat and human cells is sufficient to increase overall cellular phosphatidylinositol 4-kinase activity and intracellular phosphatidylinositol 4-phosphate abundance. siRNA-mediated reduction in eEF1A2 expression concomitantly reduces phosphatidylinositol 4-kinase activity. This identifies a physical and functional relationship between eEF1A2 and PI4KIIIbeta.
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Affiliation(s)
- Sujeeve Jeganathan
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
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345
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Yakimova ET, Kapchina-Toteva VM, Laarhoven LJ, Harren FM, Woltering EJ. Involvement of ethylene and lipid signalling in cadmium-induced programmed cell death in tomato suspension cells. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2006; 44:581-9. [PMID: 17079154 DOI: 10.1016/j.plaphy.2006.09.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Accepted: 09/06/2006] [Indexed: 05/12/2023]
Abstract
Cadmium-induced cell death was studied in suspension-cultured tomato (Lycopersicon esculentum Mill.) cells (line MsK8) treated with CdSO(4). Within 24 h, cadmium treatment induced cell death in a concentration-dependent manner. Cell cultures showed recovery after 2-3 days which indicates the existence of an adaptation mechanism. Cadmium-induced cell death was alleviated by the addition of sub muM concentrations of peptide inhibitors specific to human caspases indicating that cell death proceeds through a mechanism with similarities to animal programmed cell death (PCD, apoptosis). Cadmium-induced cell death was accompanied by an increased production of hydrogen peroxide (H(2)O(2)) and simultaneous addition of antioxidants greatly reduced cell death. Inhibitors of phospholipase C (PLC) and phospholipase D (PLD) signalling pathway intermediates reduced cadmium-induced cell death. Treatment with the G-protein activator mastoparan and a cell permeable analogue of the lipid signal second messenger phosphatidic acid (PA) induced cell death. Ethylene, while not inducing cell death when applied alone, stimulated cadmium-induced cell death. Application of the ethylene biosynthesis inhibitor aminoethoxy vinylglycine (AVG) reduced cadmium-induced cell death, and this effect was alleviated by simultaneous treatment with ethylene. Together the results show that cadmium induces PCD exhibiting apoptotic-like features. The cell death process requires increased H(2)O(2) production and activation of PLC, PLD and ethylene signalling pathways.
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Affiliation(s)
- E T Yakimova
- Regional Research Centre and Extension Service of Floriculture and Agriculture (RCNPO), 1222 Negovan, Sofia, Bulgaria
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346
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Bargmann BO, Munnik T. The role of phospholipase D in plant stress responses. CURRENT OPINION IN PLANT BIOLOGY 2006; 9:515-22. [PMID: 16877031 DOI: 10.1016/j.pbi.2006.07.011] [Citation(s) in RCA: 178] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2006] [Accepted: 07/17/2006] [Indexed: 05/11/2023]
Abstract
Phospholipase D (PLD) has been implicated in multiple plant stress responses. Its gene transcription and activity increase upon exposure to various stresses, and manipulation of PLD protein levels leads to altered stress tolerance. The plant PLD family is relatively large and heterogeneous, and different PLD isoforms are involved in separate stress responses. PLD and its product, phosphatidic acid, exert their effects by functioning in signal transduction cascades and by influencing the biophysical state of lipid membranes.
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Affiliation(s)
- Bastiaan O Bargmann
- Department of Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Kruislaan 318, 1098 SM Amsterdam, The Netherlands
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347
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Zonia L, Munnik T. Cracking the green paradigm: functional coding of phosphoinositide signals in plant stress responses. Subcell Biochem 2006; 39:207-37. [PMID: 17121277 DOI: 10.1007/0-387-27600-9_9] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Laura Zonia
- Section of Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Kruislaan 318, NL-1098 SM, Amsterdam, The Netherlands
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348
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Andersson MX, Kourtchenko O, Dangl JL, Mackey D, Ellerström M. Phospholipase-dependent signalling during the AvrRpm1- and AvrRpt2-induced disease resistance responses in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2006; 47:947-59. [PMID: 16925603 DOI: 10.1111/j.1365-313x.2006.02844.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Bacterial pathogens deliver type III effector proteins into plant cells during infection. On susceptible host plants, type III effectors contribute to virulence, but on resistant hosts they betray the pathogen to the plant's immune system and are functionally termed avirulence (Avr) proteins. Recognition induces a complex suite of cellular and molecular events comprising the plant's inducible defence response. As recognition of type III effector proteins occurs inside host cells, defence responses can be elicited by in planta expression of bacterial type III effectors. We demonstrate that recognition of either of two type III effectors, AvrRpm1 or AvrRpt2 from Pseudomonas syringae, induced biphasic accumulation of phosphatidic acid (PA). The first wave of PA accumulation correlated with disappearance of monophosphatidylinosotol (PIP) and is thus tentatively attributed to activation of a PIP specific phospholipase C (PLC) in concert with diacylglycerol kinase (DAGK) activity. Subsequent activation of phospholipase D (PLD) produced large amounts of PA from structural phospholipids. This later wave of PA accumulation was several orders of magnitude higher than the PLC-dependent first wave. Inhibition of phospholipases blocked the response, and feeding PA directly to leaf tissue caused cell death and defence-gene activation. Inhibitor studies ordered these events relative to other known signalling events during the plant defence response. Influx of extracellular Ca(2+) occurred downstream of PIP-degradation, but upstream of PLD activation. Production of reactive oxygen species occurred downstream of the phospholipases. The data presented indicate that PA is a positive regulator of RPM1- or RPS2-mediated disease resistance signalling, and that the biphasic PA production may be a conserved feature of signalling induced by the coiled-coil nucleotide binding domain leucine-rich repeat class of resistance proteins.
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Affiliation(s)
- Mats X Andersson
- Department of Plant and Environmental Sciences, Göteborg University, Box 461, SE-405 30 Göteborg, Sweden
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349
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Devaiah SP, Roth MR, Baughman E, Li M, Tamura P, Jeannotte R, Welti R, Wang X. Quantitative profiling of polar glycerolipid species from organs of wild-type Arabidopsis and a phospholipase Dalpha1 knockout mutant. PHYTOCHEMISTRY 2006; 67:1907-24. [PMID: 16843506 DOI: 10.1016/j.phytochem.2006.06.005] [Citation(s) in RCA: 213] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2005] [Revised: 04/28/2006] [Accepted: 06/02/2006] [Indexed: 05/10/2023]
Abstract
Lipid profiling is a targeted metabolomics platform that provides a comprehensive analysis of lipid species with high sensitivity. Profiling based on electrospray ionization tandem mass spectrometry (ESI-MS/MS) provides quantitative data and is adaptable to high throughput analyses. Here we report the profiling of 140 apparent molecular species of polar glycerolipids in Arabidopsis leaves, flower stalks, flowers, siliques, roots, and seeds. Considerable differences in lipid species occur among these organs, providing insights into the different lipid metabolic activities in a specific organ. In addition, comparative profiling between wild-type and a knockout mutant pldalpha1 (locus ID: AT3G15730) provides insight into the metabolic function of phospholipase D (PLD) in different organs. PLDalpha1 contributes significantly to phosphatidic acid (PA) levels in roots, seeds, flowers, and flower stalks, but little to basal PA levels in siliques and leaves. In seeds of the pldalpha1 mutant plants, levels of PA, lysophosphatidylcholine, and lysophosphatidylethanolamine were significantly lower than those of wild-type seeds, suggesting a role for PLDalpha1 in membrane lipid degradation in seeds.
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350
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Zalejski C, Paradis S, Maldiney R, Habricot Y, Miginiac E, Rona JP, Jeannette E. Induction of abscisic acid-regulated gene expression by diacylglycerol pyrophosphate involves Ca2+ and anion currents in Arabidopsis suspension cells. PLANT PHYSIOLOGY 2006; 141:1555-62. [PMID: 16766676 PMCID: PMC1533963 DOI: 10.1104/pp.106.080218] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Diacylglycerol pyrophosphate (DGPP) was recently shown to be a possible intermediate in abscisic acid (ABA) signaling. In this study, reverse transcription-PCR of ABA up-regulated genes was used to evaluate the ability of DGPP to trigger gene expression in Arabidopsis (Arabidopsis thaliana) suspension cells. At5g06760, LTI30, RD29A, and RAB18 were stimulated by ABA and also specifically expressed in DGPP-treated cells. Use of the Ca2+ channel blockers fluspirilene and pimozide and the Ca2+ chelator EGTA showed that Ca2+ was required for ABA induction of DGPP formation. In addition, Ca2+ participated in DGPP induction of gene expression via stimulation of anion currents. Hence, a sequence of Ca2+, DGPP, and anion currents, constituting a core of early ABA-signaling events necessary for gene expression, is proposed.
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Affiliation(s)
- Christine Zalejski
- Université Pierre et Marie Curie-Paris 6 and Centre National de la Recherche Scientifique, FRE 2846, Physiologie Cellulaire et Moléculaire des Plantes, F-94200 Ivry-sur-Seine, France
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