Phytic Acid Synthesis and Vacuolar Accumulation in Suspension-Cultured Cells of <i>Catharanthus roseus</i> Induced by High Concentration of Inorganic Phosphate and Cations

Mitsuhashi, Naoto; Ohnishi, Miwa; Sekiguchi, Y.; Kwon, Young‐Uk; Chang, Young‐Tae; Chung, Sung‐Kee; Inoue, Yasuhiro; Reid, Robert J.; Yagisawa, Hitoshi; Mimura, Tetsuro

doi:10.1104/pp.105.060269

Cited by 53 publications

(38 citation statements)

References 44 publications

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“…As myoinositol was reported as suppressor of myo-inositol-1-phosphate synthase (MIPS) gene expression (Mitsuhashi et al 2005) and MIPS was supposed to be catalyzing the first committed step in phytic acid biosynthesis (Loewus and Murthy 2000), so reduction of 14 C incorporation into phytic acid was expected in the presence of exogenous inositol. Addition of galactose to exogenous glucose led to increased 14 C incorporation into RFOs from 14 C-glucose.…”

Section: Discussionmentioning

confidence: 99%

Phytic acid and raffinose series oligosaccharides metabolism in developing chickpea seeds

Zhawar

Kaur

Gupta

2011

Physiol Mol Biol Plants

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Phytic acid and raffinose series oligosaccharides (RFOs) have anti-nutritional properties where phytic acid chelates minerals and reduces their bioavailability to humans and other animals, and RFOs cause flatulence. Both phytic acid and RFOs cannot be digested by monogastric animals and are released as pollutant-wastes. Efforts are being made to reduce the contents of these factors without affecting the viability of seeds. This will require a thorough understanding of their metabolism in different crops. Biosynthetic pathways of both metabolites though are interlinked but not well described. This study was made on metabolism of these two contents in developing chickpea (Cicer arietinum L cv GL 769) seeds. In this study, deposition of RFOs was found to occur before deposition of phytic acid. A decline in inorganic phosphorus and increase in phospholipid phosphorus and phytic acid was observed in seeds during development. Acid phosphatase was the major phosphatase in seed as well as podwall and its activity was highest at early stage of development, thereafter it decreased. Partitioning of 14 C label from 14 Cglucose and 14 C-sucrose into RFOs and phytic acid was studied in seeds in presence of inositol, galactose and iositol and galactose, which favored the view that galactinol synthase is not the key enzyme in RFOs synthesis.

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Section: Discussionmentioning

confidence: 99%

Phytic acid and raffinose series oligosaccharides metabolism in developing chickpea seeds

Zhawar

Kaur

Gupta

2011

Physiol Mol Biol Plants

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“…Because phytase sequentially hydrolyzes phytate, releasing free myoinositol and Pi, AtPAP15 could function to increase AsA through the myoinositol pathway by increasing the supply of this substrate. As the most abundant myoinositol phosphate in plant cells, phytate accumulates predominately in vacuoles (Mitsuhashi et al, 2005). AtPAP15 might be one of a large number of hydrolytic enzymes found in the vacuole or tonoplast.…”

Section: Discussionmentioning

confidence: 99%

An Arabidopsis Purple Acid Phosphatase with Phytase Activity Increases Foliar Ascorbate

et al. 2007

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Ascorbate (AsA) is the most abundant antioxidant in plant cells and a cofactor for a large number of key enzymes. However, the mechanism of how AsA levels are regulated in plant cells remains unknown. The Arabidopsis (Arabidopsis thaliana) activationtagged mutant AT23040 showed a pleiotropic phenotype, including ozone resistance, rapid growth, and leaves containing higher AsA than wild-type plants. The phenotype was caused by activation of a purple acid phosphatase (PAP) gene, AtPAP15, which contains a dinuclear metal center in the active site. AtPAP15 was universally expressed in all tested organs in wild-type plants. Overexpression of AtPAP15 with the 35S cauliflower mosaic virus promoter produced mutants with up to 2-fold increased foliar AsA, 20% to 30% decrease in foliar phytate, enhanced salt tolerance, and decreased abscisic acid sensitivity. Two independent SALK T-DNA insertion mutants in AtPAP15 had 30% less foliar AsA and 15% to 20% more phytate than wild-type plants and decreased tolerance to abiotic stresses. Enzyme activity of partially purified AtPAP15 from plant crude extract and recombinant AtPAP15 expressed in bacteria and yeast was highest when phytate was used as substrate, indicating that AtPAP15 is a phytase. Recombinant AtPAP15 also showed enzyme activity on the substrate myoinositol-1-phosphate, indicating that the AtPAP15 is a phytase that hydrolyzes myoinositol hexakisphosphate to yield myoinositol and free phosphate. Myoinositol is a known precursor for AsA biosynthesis in plants. Thus, AtPAP15 may modulate AsA levels by controlling the input of myoinositol into this branch of AsA biosynthesis in Arabidopsis.

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“…The reaction mix contained labeled InsP 6 at 1.85 kBq/nitrocellulose filter. (33). We labeled Ws-2 and mrp5-1 seedlings with inositol and analyzed the responsiveness of inositol hexakisphosphate synthesis to phosphate concentration in the growth and labeling media.…”

Section: Table 1 the Effect Of Abc Transport Inhibitors On Atmrp5-medmentioning

confidence: 99%

The Arabidopsis ATP-binding Cassette Protein AtMRP5/AtABCC5 Is a High Affinity Inositol Hexakisphosphate Transporter Involved in Guard Cell Signaling and Phytate Storage

Nagy

Grob

Weder

et al. 2009

Journal of Biological Chemistry

178

201

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Arabidopsis possesses a superfamily of ATP-binding cassette (ABC) transporters. Among these, the multidrug resistance-associated protein AtMRP5/AtABCC5 regulates stomatal aperture and controls plasma membrane anion channels of guard cells. Remarkably, despite the prominent role of AtMRP5 in conferring partial drought insensitivity upon Arabidopsis, we know little of the biochemical function of AtMRP5. Our phylogenetic analysis showed that AtMRP5 is closely related to maize MRP4, mutation of which confers a low inositol hexakisphosphate kernel phenotype. We now show that insertion mutants of AtMRP5 display a low inositol hexakisphosphate phenotype in seed tissue and that this phenotype is associated with alterations of mineral cation and phosphate status. By heterologous expression in yeast, we demonstrate that AtMRP5 encodes a specific and high affinity ATP-dependent inositol hexakisphosphate transporter that is sensitive to inhibitors of ABC transporters. Moreover, complementation of the mrp5-1 insertion mutants of Arabidopsis with the AtMRP5 cDNA driven from a guard cell-specific promoter restores the sensitivity of the mutant to abscisic acid-mediated inhibition of stomatal opening. Additionally, we show that mutation of residues of the Walker B motif prevents restoring the multiple phenotypes associated with mrp5-1. Our findings highlight a novel function of plant ABC transporters that may be relevant to other kingdoms. They also extend the signaling repertoire of this ubiquitous inositol polyphosphate signaling molecule.Guard cells form pairs of cells, which are conjoined at their ends, in the epidermis of the aerial tissues of plants. The cells surround a central pore, the stoma, through which gas exchange occurs. The principal gases exchanged are CO 2 and water vapor, and the function of the stomatal complex may be considered as the maximization of CO 2 assimilation by photosynthesis for the minimization of water loss.Guard cells and hence the aperture of the central pore are sensitive to environmental factors including light, temperature, CO 2 , and ozone (1). Stomatal closure is initiated by the drought stress hormone abscisic acid (ABA).3 The closure of stomata is a result of a loss of turgor of the delimiting guard cells as a consequence of ion efflux, predominantly Cl Ϫ and K ϩ , and metabolic conversion of organic acids into starch (2).Although the molecular identity of genes encoding the outward and inward K ϩ conductances are known for Arabidopsis thaliana (3), it remains to be demonstrated whether the recently identified SLAC protein (4, 5) encodes the S-type anion channel or is a subunit thereof.The ATP-binding cassette family of membrane proteins is among the most ubiquitous and variable group of membrane proteins and is most commonly associated with membrane transport phenomena. The substrates transported are especially diverse, and consequently a major obstacle to the interpretation of ABC transporter function, particularly pertinent in the context of guard cell function, is the identificatio...

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Phytic Acid Synthesis and Vacuolar Accumulation in Suspension-Cultured Cells of Catharanthus roseus Induced by High Concentration of Inorganic Phosphate and Cations

Cited by 53 publications

References 44 publications

Phytic acid and raffinose series oligosaccharides metabolism in developing chickpea seeds

Phytic acid and raffinose series oligosaccharides metabolism in developing chickpea seeds

An Arabidopsis Purple Acid Phosphatase with Phytase Activity Increases Foliar Ascorbate

The Arabidopsis ATP-binding Cassette Protein AtMRP5/AtABCC5 Is a High Affinity Inositol Hexakisphosphate Transporter Involved in Guard Cell Signaling and Phytate Storage

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