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Journal ArticleDOI

The Arabidopsis thaliana Myo-Inositol 1-Phosphate Synthase1 Gene Is Required for Myo-inositol Synthesis and Suppression of Cell Death

TL;DR: MIPS1 has a significant impact on myo-inositol levels that is critical for maintaining levels of ascorbic acid, phosphatidyl inositol, and ceramides that regulate growth, development, and cell death.
Abstract: l-myo-inositol 1-phosphate synthase (MIPS; EC 5.5.1.4) catalyzes the rate-limiting step in the synthesis of myo-inositol, a critical compound in the cell. Plants contain multiple MIPS genes, which encode highly similar enzymes. We characterized the expression patterns of the three MIPS genes in Arabidopsis thaliana and found that MIPS1 is expressed in most cell types and developmental stages, while MIPS2 and MIPS3 are mainly restricted to vascular or related tissues. MIPS1, but not MIPS2 or MIPS3, is required for seed development, for physiological responses to salt and abscisic acid, and to suppress cell death. Specifically, a loss in MIPS1 resulted in smaller plants with curly leaves and spontaneous production of lesions. The mips1 mutants have lower myo-inositol, ascorbic acid, and phosphatidylinositol levels, while basal levels of inositol (1,4,5)P3 are not altered in mips1 mutants. Furthermore, mips1 mutants exhibited elevated levels of ceramides, sphingolipid precursors associated with cell death, and were complemented by a MIPS1-green fluorescent protein (GFP) fusion construct. MIPS1-, MIPS2-, and MIPS3-GFP each localized to the cytoplasm. Thus, MIPS1 has a significant impact on myo-inositol levels that is critical for maintaining levels of ascorbic acid, phosphatidylinositol, and ceramides that regulate growth, development, and cell death.
Citations
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Journal ArticleDOI
TL;DR: In parallel to its antioxidant role, GSH acts independently of NPR1 to allow increased intracellular H(2)O( 2) to activate SA signaling, a key defense response in plants.
Abstract: Aims: Through its interaction with H2O2, glutathione is a candidate for transmission of signals in plant responses to pathogens, but identification of signaling roles is complicated by its antioxidant function. Using a genetic approach based on a conditional catalase-deficient Arabidopsis mutant, cat2, this study aimed at establishing whether GSH plays an important functional role in the transmission of signals downstream of H2O2. Results: Introducing the cad2 or allelic mutations in the glutathione synthesis pathway into cat2 blocked H2O2-triggered GSH oxidation and accumulation. While no effects on NADP(H) or ascorbate were observed, and H2O2-induced decreases in growth were maintained, blocking GSH modulation antagonized salicylic acid (SA) accumulation and SA-dependent responses. Other novel double and triple mutants were produced and compared with cat2 cad2 at the levels of phenotype, expression of marker genes, nontargeted metabolite profiling, accumulation of SA, and bacterial resistance. ...

223 citations


Cites background from "The Arabidopsis thaliana Myo-Inosit..."

  • ...Several recent publications have implicated myo-inositol in SA-dependent responses (8, 15, 35)....

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Journal ArticleDOI
TL;DR: Results and reanalyze published datasets on metabolite profiles in catalase-deficient plants are presented and the roles of ROS-triggered changes in metabolites as potential oxidative signals are emphasized.

183 citations


Cites background from "The Arabidopsis thaliana Myo-Inosit..."

  • ...Mutants for a specific myo-inositol phosphate synthase (MIPS1) show a lesion phenotype in long days or at increased growth irradiance (Meng et al., 2009; Donahue et al., 2010) that is similar to a spreading HR previously described in other lesion mimic mutants (Dietrich et al....

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  • ...Mutants for a specific myo-inositol phosphate synthase (MIPS1) show a lesion phenotype in long days or at increased growth irradiance (Meng et al., 2009; Donahue et al., 2010) that is similar to a spreading HR previously described in other lesion mimic mutants (Dietrich et al., 1994)....

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Journal ArticleDOI
TL;DR: This work has identified and characterized several lesion mimic mutants (LMM) and their related suppressors and shed light on major pathways in the onset of plant PCD such as the involvements of chloroplasts and light energy, and the roles of sphingolipids and fatty acids.
Abstract: Programmed cell death (PCD) is a ubiquitous genetically regulated process consisting in an activation of finely controlled signaling pathways that lead to cellular suicide. Although some aspects of PCD control appear evolutionary conserved between plants, animals and fungi, the extent of conservation remains controversial. Over the last decades, identification and characterization of several lesion mimic mutants (LMM) has been a powerful tool in the quest to unravel PCD pathways in plants. Thanks to progress in molecular genetics, mutations causing the phenotype of a large number of LMM and their related suppressors were mapped, and the identification of the mutated genes shed light on major pathways in the onset of plant PCD such as (i) the involvements of chloroplasts and light energy, (ii) the roles of sphingolipids and fatty acids, (iii) a signal perception at the plasma membrane that requires efficient membrane trafficking, (iv) secondary messengers such as ion fluxes and ROS and (v) the control of gene expression as the last integrator of the signaling pathways.

154 citations

Journal ArticleDOI
TL;DR: This review cross examine and analyze the major findings that establish and strengthen the intimate connections between sphingolipid metabolism and plant programmed cell death (PCD) associated with plant defense or disease and identify potential parallels for immunity-related mechanisms involving spindingolipids across kingdoms.
Abstract: Sphingolipids comprise a major class of structural materials and lipid signaling molecules in all eukaryotic cells. Over the past two decades, there has been a phenomenal growth in the study of sphingolipids (i.e. sphingobiology) at an average rate of >1000 research articles per year. Sphingolipid studies in plants, though accounting for only a small fraction (~6%) of the total number of publications, have also enjoyed proportionally rapid growth in the past decade. Concomitant with the growth of sphingobiology, there has also been tremendous progress in our understanding of the molecular mechanisms of plant innate immunity. In this review, we (i) cross examine and analyze the major findings that establish and strengthen the intimate connections between sphingolipid metabolism and plant programmed cell death (PCD) associated with plant defense or disease; (ii) highlight and compare key bioactive sphingolipids involved in the regulation of plant PCD and possibly defense; (iii) discuss the potential role of sphingolipids in polarized membrane/protein trafficking and formation of lipid rafts as subdomains of cell membranes in relation to plant defense; and (iv) where possible, attempt to identify potential parallels for immunity-related mechanisms involving sphingolipids across kingdoms.

149 citations


Cites background from "The Arabidopsis thaliana Myo-Inosit..."

  • ...Consistently, mutant plants lacking myo-inositol 1-phosphate synthase 1 (MIPS1) exhibited PCD and enhanced basal resistance to pathogens, which was accompanied by elevated ceramides and hydroxyceramides (Meng et al., 2009; Donahue et al., 2010)....

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Journal ArticleDOI
TL;DR: This article showed that AtSLD1 mutants showed a 50% reduction in glucosylceramide levels and a corresponding increase in glycosylinositolphosphoceramides.
Abstract: Summary Plants contain a large diversity of sphingolipid structures, arising in part from C4 hydroxylation and Δ4 and Δ8 desaturation of the component long-chain bases (LCBs). Typically, 85–90% of sphingolipid LCBs in Arabidopsis leaves contain a cis or transΔ8 double bond produced by sphingoid LCB Δ8 desaturase (SLD). To understand the metabolic and physiological significance of Δ8 unsaturation, studies were performed using mutants of the Arabidopsis SLD genes AtSLD1 and AtSLD2. Our studies revealed that both genes are constitutively expressed, the corresponding polypeptides are ER-localized, and expression of these genes in Saccharomyces cerevisiae yields mixtures of cis/transΔ8 desaturation products, predominantly as trans isomers. Consistent in part with the higher expression of AtSLD1 in Arabidopsis plants, AtSLD1 T-DNA mutants showed large reductions in Δ8 unsaturated LCBs in all organs examined, whereas AtSLD2 mutants showed little change in LCB unsaturation. Double mutants of AtSLD1 and AtSLD2 showed no detectable LCB Δ8 unsaturation. Comprehensive analysis of sphingolipids in rosettes of these mutants revealed a 50% reduction in glucosylceramide levels and a corresponding increase in glycosylinositolphosphoceramides that were restored by complementation with a wild-type copy of AtSLD1. Double sld1 sld2 mutants lacked apparent growth phenotypes under optimal conditions, but displayed altered responses to certain stresses, including prolonged exposure to low temperatures. These results are consistent with a role for LCB Δ8 unsaturation in selective channeling of ceramides for the synthesis of complex sphingolipids and the physiological performance of Arabidopsis.

139 citations

References
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Journal ArticleDOI
01 Aug 2003-Science
TL;DR: Genome-wide analysis of the distribution of integration events revealed the existence of a large integration site bias at both the chromosome and gene levels, and insertion mutations were identified in genes that are regulated in response to the plant hormone ethylene.
Abstract: Over 225,000 independent Agrobacterium transferred DNA (T-DNA) insertion events in the genome of the reference plant Arabidopsis thaliana have been created that represent near saturation of the gene space. The precise locations were determined for more than 88,000 T-DNA insertions, which resulted in the identification of mutations in more than 21,700 of the approximately 29,454 predicted Arabidopsis genes. Genome-wide analysis of the distribution of integration events revealed the existence of a large integration site bias at both the chromosome and gene levels. Insertion mutations were identified in genes that are regulated in response to the plant hormone ethylene.

5,227 citations

Journal ArticleDOI
TL;DR: The GATEWAY conversion technology has provided a fast and reliable alternative to the cloning of sequences into large acceptor plasmids for transformation of a wide range of plant species.

3,473 citations


"The Arabidopsis thaliana Myo-Inosit..." refers methods in this paper

  • ...fromCS60000 cDNA and cloned into vector pK7FWG2 (Karimi et al., 2002)...

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  • ...Constructs and Imaging Intergenic regions containing promoters forMIPS1 (1907 bp),MIPS2 (1106 bp), andMIPS3 (1907 bp) were amplified from CS60000 genomic DNA by PCR and cloned via the Gateway system into pBGWFS7 (Karimi et al., 2002) containing a Egfp:uidA gene fusion....

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  • ...PCR and cloned via the Gateway system into pBGWFS7 (Karimi et al., 2002) containing a Egfp:uidA gene fusion....

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  • ...MIPS1, MIPS2, and MIPS3 open reading frames without stop codons were amplified by PCR fromCS60000 cDNA and cloned into vector pK7FWG2 (Karimi et al., 2002) for expression of GFP fusions and into vector pDEST17 (Invitrogen) for expression of His-tagged proteins....

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01 Jan 1993
TL;DR: In this article, a nouvelle methode de transformation in situ par Agrobacterium is presented, based on l'infiltration sous vide de plantes d'Arabidopsis par une souche d'Agrobacteria contenant un vecteur binaire.
Abstract: Nous presentons une nouvelle methode de transformation in situ par Agrobacterium. Cette approche est basee sur l'infiltration sous vide de plantes d'Arabidopsis par une souche d'Agrobacterium contenant un vecteur binaire. Les plantes caracterisees apres leur developpement presentaient des secteurs vegetatifs transformes parmi des secteurs non transformes. En moyenne jusqu'a 5 transformants par paire inoculee ont ete selectionnes dans la descendance des plantes infiltrees. Leur analyse genetique et moleculaire suggere que la transformation a lieu tardivement, lors du dveloppement floral, car tous les transformants sont hemizygotes et possedent des sites differents d'insertion de l'ADN-T [...]

1,974 citations

Journal ArticleDOI
05 Apr 2007-Nature
TL;DR: These structures show that the leucine-rich repeat domain of TIR1 contains an unexpected inositol hexakisphosphate co-factor and recognizes auxin and the Aux/IAA polypeptide substrate through a single surface pocket, establishing the first structural model of a plant hormone receptor.
Abstract: Auxin is a pivotal plant hormone that controls many aspects of plant growth and development. Perceived by a small family of F-box proteins including transport inhibitor response 1 (TIR1), auxin regulates gene expression by promoting SCF ubiquitin-ligase-catalysed degradation of the Aux/IAA transcription repressors, but how the TIR1 F-box protein senses and becomes activated by auxin remains unclear. Here we present the crystal structures of the Arabidopsis TIR1-ASK1 complex, free and in complexes with three different auxin compounds and an Aux/IAA substrate peptide. These structures show that the leucine-rich repeat domain of TIR1 contains an unexpected inositol hexakisphosphate co-factor and recognizes auxin and the Aux/IAA polypeptide substrate through a single surface pocket. Anchored to the base of the TIR1 pocket, auxin binds to a partially promiscuous site, which can also accommodate various auxin analogues. Docked on top of auxin, the Aux/IAA substrate peptide occupies the rest of the TIR1 pocket and completely encloses the hormone-binding site. By filling in a hydrophobic cavity at the protein interface, auxin enhances the TIR1-substrate interactions by acting as a 'molecular glue'. Our results establish the first structural model of a plant hormone receptor.

1,391 citations


"The Arabidopsis thaliana Myo-Inosit..." refers background in this paper

  • ...InsP6 has also been implicated in other processes, includingmRNAexport in yeast and animals (Alcazar-Roman et al., 2006), while in plants, it is associated with the Transport Inhibitor Response 1 auxin receptor (Tan et al., 2007)....

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  • ...…such as regulation of gene expression (Alcazar-Roman andWente, 2008), phosphorus storage (Raboy and Bowen, 2006), auxin receptor association (Tan et al., 2007),membrane tethering (Fujita and Jigami, 2008), stress tolerance (Taji et al., 2006), oligosaccharide synthesis (galactinol) (Karner…...

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Journal ArticleDOI
TL;DR: Identification of the cpr5 mutation indicates that these pathways are connected in early signal transduction steps and that they have overlapping functions in providing resistance.
Abstract: The cpr5 mutant was identified from a screen for constitutive expression of systemic acquired resistance (SAR). This single recessive mutation also leads to spontaneous expression of chlorotic lesions and reduced trichome development. The cpr5 plants were found to be constitutively resistant to two virulent pathogens, Pseudomonas syringae pv maculicola ES4326 and Peronospora parasitica Noco2; to have endogenous expression of the pathogenesis-related gene 1 (PR-1); and to have an elevated level of salicylic acid (SA). Lines homozygous for cpr5 and either the SA-degrading bacterial gene nahG or the SA-insensitive mutation npr1 do not express PR-1 or exhibit resistance to P. s. maculicola ES4326. Therefore, we conclude that cpr5 acts upstream of SA in inducing SAR. However, the cpr5 npr1 plants retained heightened resistance to P. parasitica Noco2 and elevated expression of the defensin gene PDF1.2, implying that NPR1-independent resistance signaling also occurs. We conclude that the cpr5 mutation leads to constitutive expression of both an NPR1-dependent and an NPR1-independent SAR pathway. Identification of this mutation indicates that these pathways are connected in early signal transduction steps and that they have overlapping functions in providing resistance.

676 citations


"The Arabidopsis thaliana Myo-Inosit..." refers background in this paper

  • ...…the mips1 mutants share characteristics with other lesion-mimic mutants (Lorrain et al., 2003) in that light potentiates the devel- opment of lesions (Bowling et al., 1997; Jambunathan et al., 2001; Lorrain et al., 2004), and the overall gene expression pattern is similar to lesion mimics as well…...

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  • ..., 2003) in that light potentiates the development of lesions (Bowling et al., 1997; Jambunathan et al., 2001; Lorrain et al., 2004), and the overall gene expression pattern is similar to lesion mimics as well as plants exposed to abiotic stress (Meng et al....

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