Inositols and Their Metabolites in Abiotic and Biotic Stress Responses

Taji, Teruaki; Takahashi, Shigetoshi; Shinozaki, Kazuo

doi:10.1007/0-387-27600-9_10

Cited by 26 publications

(23 citation statements)

References 140 publications

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“…To test whether known stress physiological pathways that use myo-inositol signaling (Xiong et al, 2001;Taji et al, 2006) were altered in mips mutants, we produced age-matched seed populations that had been harvested from plants grown at the same time. Control and mutant age-matched seeds were plated on Murashige and Skoog (MS) medium in the presence of various concentrations of ABA, NaCl, or mannitol and stratified for 3 d at 48C.…”

Section: Mips1 Is Required For Physiological Responsesmentioning

confidence: 99%

“…In multicellular eukaryotes, myo-inositol becomes incorporated into phosphatidylinositol phosphate (PtdInsP), myo-inositol phosphate (InsP), and certain sphingolipid signaling molecules that function in many processes, such as regulation of gene expression (Alcazar-Roman and Wente, 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 et al, 2004;Michell, 2007), and regulation of cell death (sphingolipids) Liang et al, 2003). The oxidation product of myo-inositol (D-glucuronic acid) is used for cell wall pectic noncellulosic compounds (Loewus et al, 1962;Loewus, 1965Loewus, , 2006 and, in some organisms, for synthesis of ascorbic acid (Baig et al, 1970;Allison and Stewart, 1973;Banhegyi et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

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TheArabidopsis thaliana Myo-Inositol 1-Phosphate Synthase1 Gene Is Required forMyo-inositol Synthesis and Suppression of Cell Death

et al. 2010

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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)P 3 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.

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Section: Mips1 Is Required For Physiological Responsesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

TheArabidopsis thaliana Myo-Inositol 1-Phosphate Synthase1 Gene Is Required forMyo-inositol Synthesis and Suppression of Cell Death

et al. 2010

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“…Since a reduction in myoinositol synthesis could affect many processes such as myoinositol phosphate signaling or ascorbate synthesis (Fig. 1), we tested whether known stress physiological pathways that utilize myoinositol signaling (for review, see Xiong et al, 2002;Taji et al, 2006) were altered in vtc4 mutants. We produced agematched seed populations that had been harvested from plants grown at the same time.…”

Section: Growth Of Vtc4 Mutantsmentioning

confidence: 99%

“…7 and 8). These alterations could result from the small decrease in myoinositol contents, which could affect either myoinositol signaling or the production of downstream metabolites such as pinitol, a myoinositol derivative involved in osmoprotection (for review, see Taji et al, 2006). Alternatively, since ascorbate is important for detoxifying ROS generated from stress (for review, see Noctor, 2006), alterations in vtc4 mutants may result from their lowered ascorbate levels.…”

Section: Genetic Evidence For Imp Bifunctionalitymentioning

confidence: 99%

“…In multiceullar eukaryotes, myoinositol becomes incorporated into many crucial cellular compounds, including those involved in signal transduction such as phosphatidylinositol phosphates and myoinositol phosphates (InsPs; for review, see Boss et al, 2006), gene expression (InsPs; for review, see Alcazar-Roman and Wente, 2007), auxin perception and phosphorus storage (myoinositol hexakisphosphate [InsP 6 ]; for review, see Raboy and Bowen, 2006;Tan et al, 2007), membrane tethering (glycerophosphoinositide anchors; for review, see Fujita and Jigami, 2007), stress tolerance (ononitol, pinitol; for review, see Taji et al, 2006), and oligosaccharide synthesis (galactinol; for review, see Karner et al, 2004;Fig. 1).…”

mentioning

confidence: 99%

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VTC4 Is a Bifunctional Enzyme That Affects Myoinositol and Ascorbate Biosynthesis in Plants

et al. 2009

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Myoinositol synthesis and catabolism are crucial in many multiceullar eukaryotes for the production of phosphatidylinositol signaling molecules, glycerophosphoinositide membrane anchors, cell wall pectic noncellulosic polysaccharides, and several other molecules including ascorbate. Myoinositol monophosphatase (IMP) is a major enzyme required for the synthesis of myoinositol and the breakdown of myoinositol (1,4,5)trisphosphate, a potent second messenger involved in many biological activities. It has been shown that the VTC4 enzyme from kiwifruit (Actinidia deliciosa) has similarity to IMP and can hydrolyze L-galactose 1-phosphate (L-Gal 1-P), suggesting that this enzyme may be bifunctional and linked with two potential pathways of plant ascorbate synthesis. We describe here the kinetic comparison of the Arabidopsis (Arabidopsis thaliana) recombinant VTC4 with D-myoinositol 3-phosphate (D-Ins 3-P) and L-Gal 1-P. Purified VTC4 has only a small difference in the V max /K m for L-Gal 1-P as compared with D-Ins 3-P and can utilize other related substrates. Inhibition by either Ca 2+ or Li + , known to disrupt cell signaling, was the same with both L-Gal 1-P and D-Ins 3-P. To determine whether the VTC4 gene impacts myoinositol synthesis in Arabidopsis, we isolated T-DNA knockout lines of VTC4 that exhibit small perturbations in abscisic acid, salt, and cold responses. Analysis of metabolite levels in vtc4 mutants showed that less myoinositol and ascorbate accumulate in these mutants. Therefore, VTC4 is a bifunctional enzyme that impacts both myoinositol and ascorbate synthesis pathways.

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