Mutations in genes controlling the biosynthesis and accumulation of inositol phosphates in seeds

2010 ◽  
Vol 38 (2) ◽  
pp. 689-694 ◽  
Author(s):  
Søren K. Rasmussen ◽  
Christina Rønn Ingvardsen ◽  
Anna Maria Torp
Keyword(s):  
Phytic Acid ◽  
Biosynthetic Pathway ◽  
Molecular Breeding ◽  
Inositol Phosphates ◽  
Plant Seeds ◽  
Protein Storage Vacuoles ◽  
Insertion Elements ◽  
Induced Mutagenesis ◽  
Inositol Ring ◽  
Days After Anthesis

Most of the phosphorus in the resting seed is stored inside protein storage vacuoles as PA (phytic acid; InsP6). The biosynthesis and accumulation of PA can be detected beginning from a few days after anthesis and seem to continue during seed development until maturation. The first step in PA biosynthesis is the formation of Ins3P by conversion of glucose 6-phosphate. This is then followed by a sequential and ordered phosphorylation of the remaining five positions of the inositol ring by a number of kinases, resulting in PA. Identification of low-PA mutants in cereals, legumes and Arabidopsis is instrumental for resolving the biosynthetic pathway and identification of genes controlling the accumulation of PA. Mutations in seven genes involved in the metabolism of PA have been identified and characterized among five plant species using induced mutagenesis and insertion elements. Understanding the biosynthetic pathway and genes controlling the accumulation of PA in plant seeds and how PA may balance the free phosphate is of importance for molecular breeding of crop plants, particularly cereals and legumes.

Phosphate, inositol and polyphosphates

2016 ◽  
Vol 44 (1) ◽  
pp. 253-259 ◽  
Author(s):  
Thomas M. Livermore ◽  
Cristina Azevedo ◽  
Bernadett Kolozsvari ◽  
Miranda S.C. Wilson ◽  
Adolfo Saiardi
Keyword(s):  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
High Energy ◽  
Inorganic Polyphosphate ◽  
Covalent Bonds ◽  
Polymeric Form ◽  
Phosphodiester Bond ◽  
Signalling Molecules ◽  
Inositol Ring ◽  
Phosphate Groups

Eukaryotic cells have ubiquitously utilized the myo-inositol backbone to generate a diverse array of signalling molecules. This is achieved by arranging phosphate groups around the six-carbon inositol ring. There is virtually no biological process that does not take advantage of the uniquely variable architecture of phosphorylated inositol. In inositol biology, phosphates are able to form three distinct covalent bonds: phosphoester, phosphodiester and phosphoanhydride bonds, with each providing different properties. The phosphoester bond links phosphate groups to the inositol ring, the variable arrangement of which forms the basis of the signalling capacity of the inositol phosphates. Phosphate groups can also form the structural bridge between myo-inositol and diacylglycerol through the phosphodiester bond. The resulting lipid-bound inositol phosphates, or phosphoinositides, further expand the signalling potential of this family of molecules. Finally, inositol is also notable for its ability to host more phosphates than it has carbons. These unusual organic molecules are commonly referred to as the inositol pyrophosphates (PP-IPs), due to the presence of high-energy phosphoanhydride bonds (pyro- or diphospho-). PP-IPs themselves constitute a varied family of molecules with one or more pyrophosphate moiety/ies located around the inositol. Considering the relationship between phosphate and inositol, it is no surprise that members of the inositol phosphate family also regulate cellular phosphate homoeostasis. Notably, the PP-IPs play a fundamental role in controlling the metabolism of the ancient polymeric form of phosphate, inorganic polyphosphate (polyP). Here we explore the intimate links between phosphate, inositol phosphates and polyP, speculating on the evolution of these relationships.

scholarly journals Inositol phosphates: health implications, methods of analysis, and occurrence in plant foods

2018 ◽  
Vol 1 ◽  
Author(s):  
Quynh H. Duong ◽  
Karen G. Lapsley ◽  
Ronald B. Pegg
Keyword(s):  
Inositol Phosphates ◽  
Negative Effects ◽  
Plant Foods ◽  
Plant Seeds ◽  
Cell Functions ◽  
Wide Range ◽  
Multiple Cell ◽  
The Relationship

Inositol phosphates (InsPs), especially myo-inositol hexakisphosphate (InsP6), are important binders of phosphorus and minerals in plant seeds. However, they have long been considered as anti-nutritional components of plant foods due to their possible negative effects on the absorption of minerals and proteins in mammals. On the other hand, recent findings have found InsPs to be ubiquitous in eukaryote cells and actively participating in multiple cell functions. In vivo and in vitro studies have also documented the preventive potential of these compounds against the development of a wide range of diseases. In light of these findings, interest in the relationship between these compounds and human health has been renewed. It is suggested that the interactions of InsPs with other nutrients in the gut are complex, that the absorption of dietary InsPs might be implied but is not certain, and that the disease fighting capabilities of InsPs hold both promises and limitations. At the same time, the analysis of these compounds in foods and biological samples still faces many challenges, calling for more advanced modification and developments in the future.

scholarly journals Formation of methylphosphoryl inositol phosphates by extractions that employ methanol

1988 ◽  
Vol 253 (3) ◽  
pp. 703-710 ◽  
Author(s):  
J E Brown ◽  
M Rudnick ◽  
A J Letcher ◽  
R F Irvine
Keyword(s):  
Alkaline Phosphatase ◽  
Methanol Extract ◽  
Inositol Phosphates ◽  
Red Cell ◽  
Unknown Compound ◽  
Methyl Group ◽  
Phosphatidylinositol Bisphosphate ◽  
Inositol 1,4,5 Trisphosphate ◽  
Inositol Ring ◽  
Retinal Volume

Fixatives that contain methanol extract an unknown compound from several tissues including the retinas of squid (Loligo). We have determined that the compound probably contains (1) a myo-inositol ring that is phosphorylated in more than one position (including at the 5-hydroxyl), (2) a charged moiety that is not susceptible to alkaline phosphatase, and (3) a methyl group. We have found that the compound can be made by treating either phosphatidylinositol bisphosphate or human red cell ghosts with acidic methanol. We have confirmed the observation of Lips, Bross & Majerus [Proc. Natl. Acad. Sci. U.S.A. 85, 88-92] that the compound also can be made by methanolysis of inositol (cyclic 1:2,4,5)trisphosphate; however, we have not found inositol (cyclic 1:2,4,5)trisphosphate in either stimulated or unstimulated squid retinas. We tentatively identify the compound as (1-methylphosphoryl)inositol 4,5-bisphosphate formed by methanolysis of phosphatidylinositol 4,5-bisphosphate. By using this methanolysis to incorporate label from [14C]methanol, we have estimated the mass of inositol 1,4,5-trisphosphate in squid retinas to be approx. 30 mumol/l of retinal volume.

scholarly journals lpa1-5525: A New lpa1 Mutant Isolated in a Mutagenized Population by a Novel Non-Disrupting Screening Method

Plants ◽  
2019 ◽  
Vol 8 (7) ◽  
pp. 209 ◽  
Author(s):  
Giulia Borlini ◽  
Cesare Rovera ◽  
Michela Landoni ◽  
Elena Cassani ◽  
Roberto Pilu
Keyword(s):  
Phytic Acid ◽  
Screening Method ◽  
Lower Amount ◽  
Wild Type ◽  
New Mutation ◽  
Breeding Programs ◽  
Low Phytic Acid ◽  
Protein Storage Vacuoles ◽  
Mixed Salts ◽  
Phytic Phosphorus

Phytic acid, or myo-inositol 1,2,3,4,5,6-hexakisphosphate, is the main storage form of phosphorus in plants. It is localized in seeds, deposited as mixed salts of mineral cations in protein storage vacuoles; during germination, it is hydrolyzed by phytases to make available P together with all the other cations needed for seed germination. When seeds are used as food or feed, phytic acid and the bound cations are poorly bioavailable for human and monogastric livestock due to their lack of phytase activity. Therefore, reducing the amount of phytic acid is one strategy in breeding programs aimed to improve the nutritional properties of major crops. In this work, we present data on the isolation of a new maize (Zea mays L.) low phytic acid 1 (lpa1) mutant allele obtained by transposon tagging mutagenesis with the Ac element. We describe the generation of the mutagenized population and the screening to isolate new lpa1 mutants. In particular, we developed a fast, cheap and non-disrupting screening method based on the different density of lpa1 seed compared to the wild type. This assay allowed the isolation of the lpa1-5525 mutant characterized by a new mutation in the lpa1 locus associated with a lower amount of phytic phosphorus in the seeds in comparison with the wild type.

scholarly journals Effects of inositol starvation on the levels of inositol phosphates and inositol lipids in Neurospora crassa

1993 ◽  
Vol 292 (3) ◽  
pp. 805-811 ◽  
Author(s):  
P L Lakin-Thomas
Keyword(s):  
Neurospora Crassa ◽  
Phytic Acid ◽  
Inositol Phosphates ◽  
Acid Synthesis ◽  
Extracellular Medium ◽  
Absolute Requirement ◽  
Solid Agar ◽  
Inositol Lipids ◽  
Agar Media ◽  
High Concentrations

An inositol-requiring strain of Neurospora crassa was labelled during growth in liquid medium with [3H]inositol, and the levels of inositol phosphates and phosphoinositides were determined under inositol-sufficient and inositol-starved conditions. Because the mutant has an absolute requirement for inositol, the total mass of inositol-containing compounds could be determined. Inositol-containing lipids were identified by deacylation and co-migration with standards on h.p.l.c.; PtdIns3P, PtdIns4P, and PtdIns(4,5)P2 were found in approximately equal amounts, in addition to large amounts of PtdIns. Inositol starvation decreased the level of PtdIns to 10% of the sufficient level, and decreased the levels of the other phosphoinositides to about 25%. A number of inositol phosphates were found, including several InsP3s, InsP4s and InsP5s and phytic acid. Ins(1,4,5)P3 was identified by co-migration with standards on h.p.l.c. and by digestion with inositol phosphomonoesterase. High concentrations of all inositol phosphates were found in the extracellular medium in inositol-starved cultures. Inositol starvation on both liquid and solid agar media decreased the intracellular levels of some inositol phosphates, but increased the levels of phytic acid and several other inositol phosphates which may be its precursors and/or breakdown products. These results may indicate that inositol starvation induces phytic acid synthesis as a protection against the free-radical production and lipid peroxidation characteristic of inositol-less death.

scholarly journals Molecular breeding for transgenic rice with low-phytic-acid phenotype through manipulating myo-inositol 3-phosphate synthase gene

2006 ◽  
Vol 18 (3) ◽  
pp. 263-272 ◽  
Author(s):  
Mio Kuwano ◽  
Akio Ohyama ◽  
Yusuke Tanaka ◽  
Tetsuro Mimura ◽  
Fumio Takaiwa ◽  
...  
Keyword(s):  
Phytic Acid ◽  
Transgenic Rice ◽  
Molecular Breeding ◽  
Low Phytic Acid ◽  
Phosphate Synthase
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