Inositol phosphates from barley low-phytate grain mutants analysed by metal-dye detection HPLC and NMR

Hatzack, Frank; Hübel, Frank; Zhang, Wei; Hansen, Poul Erik; Rasmussen, Søren K.

doi:10.1042/0264-6021:3540473

Cited by 34 publications

(30 citation statements)

References 32 publications

(55 reference statements)

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“…In the lap2-1 allele, the genomic sequence is rearranged in the ZmIpk locus and ZmIpk mRNA expression is undetectable. An alternative explanation could be the existence of one or more salvage pathways, as proposed in barley developing grain (Hatzack et al, 2001). However, the phenotype of ZmIpk-mum and lpa2 alleles is also consistent with a hypothesis that maize seeds have multiple inositol phosphate phosphorylation pathways for phytic acid biosynthesis.…”

Section: Discussionsupporting

confidence: 49%

“…These compounds could be intermediates of phytic acid biosynthesis. They also could be metabolic products of the intermediates because developing seeds have many inositol phosphate kinase and phosphatase activities (Biswas et al, 1984;Brearley and Hanke, 1996b;Hatzack et al, 2001). The existence of recombinant ZmIpk protein will allow testing if the ZmIpk can use these compounds and other inositol phosphates as substrates.…”

Section: Discussionmentioning

confidence: 99%

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The Maize Low-Phytic Acid Mutant lpa2 Is Caused by Mutation in an Inositol Phosphate Kinase Gene

et al. 2003

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Reduced phytic acid content in seeds is a desired goal for genetic improvement in several crops. Low-phytic acid mutants have been used in genetic breeding, but it is not known what genes are responsible for the low-phytic acid phenotype. Using a reverse genetics approach, we found that the maize (Zea mays) low-phytic acid lpa2 mutant is caused by mutation in an inositol phosphate kinase gene. The maize inositol phosphate kinase (ZmIpk) gene was identified through sequence comparison with human and Arabidopsis Ins(1,3,4)P 3 5/6-kinase genes. The purified recombinant ZmIpk protein has kinase activity on several inositol polyphosphates, including Ins(1,3,4)P 3 , Ins(3,5,6)P 3 , Ins(3,4,5,6)P 4 , and Ins(1,2,5,6)P 4 . The ZmIpk mRNA is expressed in the embryo, the organ where phytic acid accumulates in maize seeds. The ZmIpk Mutator insertion mutants were identified from a Mutator F 2 family. In the ZmIpk Mu insertion mutants, seed phytic acid content is reduced approximately 30%, and inorganic phosphate is increased about 3-fold. The mutants also accumulate myo-inositol and inositol phosphates as in the lpa2 mutant. Allelic tests showed that the ZmIpk Mu insertion mutants are allelic to the lpa2. Southern-blot analysis, cloning, and sequencing of the ZmIpk gene from lpa2 revealed that the lpa2-1 allele is caused by the genomic sequence rearrangement in the ZmIpk locus and the lpa2-2 allele has a nucleotide mutation that generated a stop codon in the N-terminal region of the ZmIpk open reading frame. These results provide evidence that ZmIpk is one of the kinases responsible for phytic acid biosynthesis in developing maize seeds.Phytic acid, myo-inositol 1,2,3,4,5,6-hexakisphosphate, is an abundant component of plant seeds and is deposited in protein bodies as a mixed salt of mineral cations, such as K ϩ , Mg 2ϩ , Ca 2ϩ , Zn 2ϩ , and Fe 3ϩ . Typically, 50% to 80% of the phosphorus in seeds is found in this compound. Phytic acid serves as a major storage form for myo-inositol, phosphorus, and mineral cations for use during seedling growth. The other known role of phytic acid is the control of inorganic phosphate (Pi) levels in both developing seeds and seedlings (Strother, 1980). In maize (Zea mays) kernels, nearly 90% of the phytic acid is accumulated in embryo and about 10% in aleurone layers. Maize endosperm contains only trace amount of phytic acid (O'Dell et al., 1972). In rice (Oryza sativa), barley (Hordeum vulgare), and wheat (Triticum aestivum), most of the phytic acid (approximately 90%) is found in the aleurone layers and only about 10% in embryo. Reduced phytic acid content in seeds is a desired goal for genetic improvement in several crops, including maize, rice, barley, wheat, and soybean (Glycine max). Because monogastric animals digest phytic acid poorly, animal feed is supplemented with Pi to meet the phosphorus requirement for animal growth. Undigested phytic acid is eliminated and is a leading phosphorus pollution source (Cromwell and Coffey, 1991). Although phytic acid as an antioxidant is sugges...

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Section: Discussionsupporting

confidence: 49%

Section: Discussionmentioning

confidence: 99%

The Maize Low-Phytic Acid Mutant lpa2 Is Caused by Mutation in an Inositol Phosphate Kinase Gene

et al. 2003

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“…1, A and B) contrasts with the biosynthetic mutant ipk1-1 and with biosynthetic mutants, for example, of barley (27,28) and maize (29,30). To test whether AtMRP5 is an inositol hexakisphosphate transporter or a membrane protein participating, but not directly catalyzing inositol hexakisphosphate transport, we expressed AtMRP5 in yeast deficient in the YCF1 ABC transporter.…”

Section: Ablation Of Atmrp5 Reduces Inositol Hexakisphosphatementioning

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

177

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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“…In addition, techniques such as nuclear magnetic resonance spectroscopy, high-performance liquid chromatography, and SDS-polyacrylamide gel electrophoresis [11,12] have been also used for the detection of phytic acid in different analytes. The use of biosensors based on the immobilization of PhyA into polymeric matrices appoints as an alternative for the detection of phytic acid.…”

Section: Introductionmentioning

confidence: 99%

Polypyrrole/phytase amperometric biosensors for the determination of phytic acid in standard solutions

Rodrigues

Moraes

Brisolari

et al. 2011

Sensors and Actuators B: Chemical

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Inositol phosphates from barley low-phytate grain mutants analysed by metal-dye detection HPLC and NMR

Cited by 34 publications

References 32 publications

The Maize Low-Phytic Acid Mutant lpa2 Is Caused by Mutation in an Inositol Phosphate Kinase Gene

The Maize Low-Phytic Acid Mutant lpa2 Is Caused by Mutation in an Inositol Phosphate Kinase Gene

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

Polypyrrole/phytase amperometric biosensors for the determination of phytic acid in standard solutions

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