Globoids and Phytase: The Mineral Storage and Release System in Seeds.

Phytate and phytases in seeds are the subjects of numerous studies, dating back as far as the early 20th century. Most of these studies concern the anti-nutritional properties of phytate, and the prospect of alleviating the effects of phytate with phytase. As reasonable as this may be, it has led to a fragmentation of knowledge, which hampers the appreciation of the physiological system at hand. In this review, we integrate the existing knowledge on the chemistry and biosynthesis of phytate, the globoid cellular structure, and recent advances on plant phytases. We highlight that these components make up a system that serves to store and-in due time-release the seed's reserves of the mineral nutrients phosphorous, potassium, magnesium, and others, as well as inositol and protein. The central component of the system, the phytate anion, is inherently rich in phosphorous and inositol. The chemical properties of phytate enable it to sequester additional cationic nutrients. Compartmentalization and membrane transport processes regulate the buildup of phytate and its associated nutrients, resulting in globoid storage structures. We suggest, based on the current evidence, that the degradation of the globoid and the mobilization of the nutrients also depend on membrane transport processes, as well as the enzymatic action of phytase.

Inositol hexakisphosphate biosynthesis underpins PAMP-triggered immunity to Pseudomonas syringae pv. tomato in Arabidopsis thaliana but is dispensable for establishment of systemic acquired resistance.

Phytic acid (inositol hexakisphosphate, InsP6 ) is an important phosphate store and signal molecule necessary for maintenance of basal resistance to plant pathogens. Arabidopsis thaliana ('arabidopsis') has three genes encoding myo-inositol phosphate synthases (IPS1-3), the enzymes that catalyse conversion of glucose-6-phosphate to InsP, the first step in InsP6 biosynthesis. There is one gene for inositol-(1,3,4,5,6)-pentakisphosphate 2-kinase (IPK1), which catalyses the final step. Previously, we showed that mutation of IPS2 and IPK1 but not IPS1 increased susceptibility to pathogens. Our aim was to better understand the InsP6 biosynthesis pathway in plant defence. Here we found that the susceptibility of arabidopsis (Col-0) to virulent and avirulent Pseudomonas syringae pv. tomato was also increased in ips3 and ips2/3 double mutants. Also, ipk1 plants had compromised expression of local acquired resistance induced by treatment with the pathogen-derived molecular pattern (PAMP) molecule flg22, but were unaffected in other responses to flg22, including Ca2+ influx and the oxidative burst, seedling root growth inhibition, and transcriptional up-regulation of the PAMP-triggered genes MITOGEN-ACTIVATED PROTEIN KINASE (MPK) 3, MPK11, CINNAMYL ALCOHOL DEHYDROGENASE 5, and FLG22-INDUCED RECEPTOR-LIKE KINASE 1. IPK1 mutation did not prevent the induction of systemic acquired resistance by avirulent P. syringae. Also, ips2 and ips2/3 double mutant plants, like ipk1, were hypersusceptible to P. syringae but were not compromised in flg22-induced local acquired resistance. The results support the role of InsP6 biosynthesis enzymes in effective basal resistance and indicate that there is more than one basal resistance mechanism dependent upon InsP6 biosynthesis.

Mutational Analysis of OsPLDα1 Reveals Its Involvement in Phytic Acid Biosynthesis in Rice Grains.

Phospholipids and phytic acid are important phosphorus (P)-containing compounds in rice grains. Phytic acid is considered as a major antinutrient, because the negatively charged phytic acid chelates cations, including essential micronutrients, and decreases their bioavailability to human beings and monogastric animals. To gain an insight into the interplay of these two kinds of phosphorus-containing metabolites, we used the CRISPR/Cas9 system to generate mutants of a phospholipase D gene (OsPLDα1) and analyzed the mutational effect on metabolites, including phytic acid in rice grains. Metabolic profiling of two ospldα1 mutants revealed depletion in the phosphatidic acid production and lower accumulation of cytidine diphosphate diacylglycerol and phosphatidylinositol. The mutants also showed significantly reduced phytic acid content as compared to their wild-type parent, and the expression of the key genes involved in the phytic acid biosynthesis was altered in the mutants. These results demonstrate that OsPLDα1 not only plays an important role in phospholipid metabolism but also is involved in phytic acid biosynthesis, most probably through the lipid-dependent pathway, and thus revealed a potential new route to regulate phytic acid biosynthesis in rice.

Novel allelic variant of Lpa1 gene associated with a significant reduction in seed phytic acid content in rice (Oryza sativa L.).

In plants, myo-inositol-1,2,3,4,5,6-hexakisphosphate (InsP6), also known as phytic acid (PA), is a major component of organic phosphorus (P), and accounts for up to 85% of the total P in seeds. In rice (Oryza sativa L.), PA mainly accumulates in rice bran, and chelates mineral cations, resulting in mineral deficiencies among brown rice consumers. Therefore, considerable efforts have been focused on the development of low PA (LPA) rice cultivars. In this study, we performed genetic and molecular analyses of OsLpa1, a major PA biosynthesis gene, in Sanggol, a low PA mutant variety developed via chemical mutagenesis of Ilpum rice cultivar. Genetic segregation and sequencing analyses revealed that a recessive allele, lpa1-3, at the OsLpa1 locus (Os02g0819400) was responsible for a significant reduction in seed PA content in Sanggol. The lpa1-3 gene harboured a point mutation (C623T) in the fourth exon of the predicted coding region, resulting in threonine (Thr) to isoleucine (Ile) amino acidsubstitution at position 208 (Thr208Ile). Three-dimensional analysis of Lpa1 protein structure indicated that myo-inositol 3-monophosphate [Ins(3)P1] could bind to the active site of Lpa1, with ATP as a cofactor for catalysis. Furthermore, the presence of Thr208 in the loop adjacent to the entry site of the binding pocket suggests that Thr208Ile substitution is involved in regulating enzyme activity via phosphorylation. Therefore, we propose that Thr208Ile substitution in lpa1-3 reduces Lpa1 enzyme activity in Sanggol, resulting in reduced PA biosynthesis.

A repeat length variation in myo-inositol monophosphatase gene contributes to seed size trait in chickpea.

Chickpea (Cicer arietinum L.) is the third most important food legume crop. Seed size is the most economically important trait for chickpea. To understand the genetic regulation of seed size in chickpea, the present study established a three-way association of CT repeat length variation of a simple sequence repeat (SSR) in myo-inositol monophosphatase gene (CaIMP) with seed weight and phytic acid content by large scale validation and genotyping in a set of genetically diverse germplasm accessions and two reciprocal intra-specific mapping populations. Germplasms and mapping individuals with CT repeat-length expansion in the 5' untranslated region of CaIMP exhibited a pronounced increase in CaIMP protein level, enzymatic activity, seed-phytate content and seed weight. A chickpea transient expression system demonstrated this repeat-length variation influenced the translation of CaIMP mRNA, apparently by facilitating translation initiation. Our analyses proposed that the SSR marker derived from 5' UTR of a CaIMP gene is a promising candidate for selection of seed size/weight for agronomic trait improvement of chickpea.

Tobacco phytaspase: Successful expression in a heterologous system.

Phytaspase, a plant serine protease, has been demonstrated to play an important role in the programmed cell death of various plants. Phytaspase is synthesized as an inactive proenzyme containing an N-terminal signal peptide followed by a pro-domain and a mature protease catalytic domain. Pre-prophytaspase autocatalytically processes itself into a pro-domain and an active mature phytaspase enzyme. We have recently demonstrated the successful expression of mature phytaspase from tobacco in a bacterial system. Herein, we focus on the expression of pre-prophytaspase as a GST-tag fusion and on its purification by affinity chromatography.

Evaluation of phytic acid utilization by S. cerevisiae strains used in fermentation processes and biomass production.

Saccharomyces cerevisiae is a well-studied yeast species used mainly in fermentation processes, bakery, and for SCP (Single Cell Protein) acquisition. The aim of the study was to analyze the possibility of phytic acid utilization as one of the hydrolysis processes carried out by yeast. The analysis of 30 yeast strains used in fermentation and for biomass production, that were grown in media containing phytic acid, revealed a high variability in the biomass production rate and the capability to hydrolyze phytates. No correlation between a high biomass concentration and a high level of phytate hydrolysis was found. Only four analyzed strains (Bayanus IOC Efficience, Sano, PINK EXCEL, FINAROME) were able to reduce the phytic acid concentration by more than 33.5%, from the initial concentration 103.0 ± 2.1 µg/ml to the level below 70 µg/ml. The presented results suggest that the selected wine and fodder yeast can be used as in situ source of phosphohydrolases in fermentation processes, and especially in the production of fodder proteins. However, further studies aimed at the optimization of growing parameters, such as the maximization of phytase secretion, and a comprehensive analysis of the catalytic activity of the isolated phosphohydrolases, are necessary.

Chalky part differs in chemical composition from translucent part of japonica rice grains as revealed by a notched-belly mutant with white-belly.

BACKGROUND: Chalkiness has a deleterious influence on rice appearance and milling quality. We identified a notched-belly mutant with a high percentage of white-belly, and thereby developed a novel comparison system that can minimize the influence of genetic background and growing conditions. Using this mutant, we examined the differences in chemical composition between chalky and translucent endosperm, with the aim of exploring relations between occurrence of chalkiness and accumulation of starch, protein and minerals. RESULTS: Comparisons showed a significant effect of chalkiness on chemical components in the endosperm. In general, occurrence of chalkiness resulted in higher total starch concentration and lower concentrations of the majority of the amino acids measured. Chalkiness also had a positive effect on the concentrations of As, Ba, Cd, Cr, Mn, Na, Sr and V, but was negatively correlated with those of B, Ca, Cu, Fe and Ni. By contrast, no significant chalkiness effect on P, phytic acid-P, K, Mg or Zn was observed. In addition, substantial influence of the embryo on endosperm composition was detected, with the embryo showing a negative effect on total protein, amino acids such as Arg, His, Leu, Lys, Phe and Tyr, and all the 17 minerals measured, excluding Ca, Cu, P and Sr. CONCLUSION: An inverse relation between starch and protein as well as amino acids was found with respect to chalkiness occurrence. Phytic acid and its colocalized elements K and Mg were not affected by chalkiness. The embryo exerted a marked influence on chemical components of the endosperm, in particular minerals, suggesting the necessity of examining the role of the embryo in chalkiness formation. © 2016 The Authors. Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Disruption of OsSULTR3;3 reduces phytate and phosphorus concentrations and alters the metabolite profile in rice grains.

Two low phytic acid (lpa) mutants have been developed previously with the aim to improve the nutritional value of rice (Oryza sativa) grains. In the present study, the impacts of lpa mutations on grain composition and underlying molecular mechanisms were investigated. Comparative compositional analyses and metabolite profiling demonstrated that concentrations of both phytic acid (PA) and total phosphorus (P) were significantly reduced in lpa brown rice, accompanied by changes in other metabolites and increased concentrations of nutritionally relevant compounds. The lpa mutations modified the expression of a number of genes involved in PA metabolism, as well as in sulfate and phosphate homeostasis and metabolism. Map-based cloning and complementation identified the underlying lpa gene to be OsSULTR3;3. The promoter of OsSULTR3;3 is highly active in the vascular bundles of leaves, stems and seeds, and its protein is localized in the endoplasmic reticulum. No activity of OsSULTR3;3 was revealed for the transport of phosphate, sulfate, inositol or inositol 1,4,5 triphosphate by heterologous expression in either yeast or Xenopus oocytes. The findings reveal that OsSULTR3;3 plays an important role in grain metabolism, pointing to a new route to generate value-added grains in rice and other cereal crops.

Identification of a major IP5 kinase in Cryptococcus neoformans confirms that PP-IP5/IP7, not IP6, is essential for virulence.

Fungal inositol polyphosphate (IP) kinases catalyse phosphorylation of IP3 to inositol pyrophosphate, PP-IP5/IP7, which is essential for virulence of Cryptococcus neoformans. Cryptococcal Kcs1 converts IP6 to PP-IP5/IP7, but the kinase converting IP5 to IP6 is unknown. Deletion of a putative IP5 kinase-encoding gene (IPK1) alone (ipk1Δ), and in combination with KCS1 (ipk1Δkcs1Δ), profoundly reduced virulence in mice. However, deletion of KCS1 and IPK1 had a greater impact on virulence attenuation than that of IPK1 alone. ipk1Δkcs1Δ and kcs1Δ lung burdens were also lower than those of ipk1Δ. Unlike ipk1Δ, ipk1Δkcs1Δ and kcs1Δ failed to disseminate to the brain. IP profiling confirmed Ipk1 as the major IP5 kinase in C. neoformans: ipk1Δ produced no IP6 or PP-IP5/IP7 and, in contrast to ipk1Δkcs1Δ, accumulated IP5 and its pyrophosphorylated PP-IP4 derivative. Kcs1 is therefore a dual specificity (IP5 and IP6) kinase producing PP-IP4 and PP-IP5/IP7. All mutants were similarly attenuated in virulence phenotypes including laccase, urease and growth under oxidative/nitrosative stress. Alternative carbon source utilisation was also reduced significantly in all mutants except ipk1Δ, suggesting that PP-IP4 partially compensates for absent PP-IP5/IP7 in ipk1Δ grown under this condition. In conclusion, PP-IP5/IP7, not IP6, is essential for fungal virulence.

Inositol hexakisphosphate (IP6) generated by IP5K mediates cullin-COP9 signalosome interactions and CRL function.

The family of cullin-RING E3 Ligases (CRLs) and the constitutive photomorphogenesis 9 (COP9) signalosome (CSN) form dynamic complexes that mediate ubiquitylation of 20% of the proteome, yet regulation of their assembly/disassembly remains poorly understood. Inositol polyphosphates are highly conserved signaling molecules implicated in diverse cellular processes. We now report that inositol hexakisphosphate (IP6) is a major physiologic determinant of the CRL-CSN interface, which includes a hitherto unidentified electrostatic interaction between the N-terminal acidic tail of CSN subunit 2 (CSN2) and a conserved basic canyon on cullins. IP6, with an EC50 of 20 nM, acts as an intermolecular "glue," increasing cullin-CSN2 binding affinity by 30-fold, thereby promoting assembly of the inactive CRL-CSN complexes. The IP6 synthase, Ins(1,3,4,5,6)P5 2-kinase (IPPK/IP5K) binds to cullins. Depleting IP5K increases the percentage of neddylated, active Cul1 and Cul4A, and decreases levels of the Cul1/4A substrates p27 and p21. Besides dysregulating CRL-mediated cell proliferation and UV-induced apoptosis, IP5K depletion potentiates by 28-fold the cytotoxic effect of the neddylation inhibitor MLN4924. Thus, IP5K and IP6 are evolutionarily conserved components of the CRL-CSN system and are potential targets for cancer therapy in conjunction with MLN4924.

Do rice suspension-cultured cells treated with abscisic acid mimic developing seeds?

Starch synthesis is activated in the endosperm during seed development and also in rice suspension cells cultured with abscisic acid. In the anticipation that the mechanisms of starch synthesis are similar between the endosperm and the suspension cells cultured with abscisic acid, expression of genes involved in starch synthesis was evaluated in the suspension cells after abscisic acid treatment. However, it was found that the regulatory mechanism of starch synthesis in the suspension cells cultured with abscisic acid was different from that in developing seeds. Expression analyses of genes involved in oil bodies, which accumulate in the embryo and aleurone layer, and seed storage proteins, which accumulate mainly in the endosperm, showed that the former were activated in the suspension cells cultured with abscisic acid, but the latter were not. Master regulators for embryogenesis, OsVP1 (homologue of AtABI3) and OsLFL1 (homologue of AtFUS3 or AtLFL2), were expressed in the suspension cells at levels comparable to those in the embryo. From these results, it is suggested that interactions between regulators and abscisic acid control the synthesis of phytic acid and oil bodies in the cultured cells and embryo. We suggest that the system of suspension cells cultured with abscisic acid helps to reveal the mechanisms of phytic acid and oil body synthesis in embryo.

Effect of germination time on proximate analysis, bioactive compounds and antioxidant activity of lentil (Lens culinaris Medik.) sprouts.

BACKGROUND: The lentil plant, Lens culinaris L., is a member of the Leguminoceae family and constitutes one of the most important traditional dietary components. The purpose of the current study was to investigate the effects of sprouting for 3, 4, 5 and 6 days on proximate, bioactive compounds and antioxidative characteristics of lentil (Lens culinaris) sprouts. MATERIAL AND METHODS: Lentil seeds were soaked in distilled water (1:10, w/v) for 12 h at room temperature (~25°C), then kept between thick layers of cotton cloth and allowed to germinate in the dark for 3, 4, 5 and 6 days. The nutritional composition, protein solubility, free amino acids, antinutritional factors, bioactive compounds and antioxidant activity of raw and germinated samples were determined using standard official procedures. RESULTS: Sprouting process caused significant (P ≤ 0.05) increases in moisture, protein, ash, crude fiber, protein solubility, free amino acids, total, reducing and nonreducing sugars. However, oil content, antinutritional factors (tannins and phytic acid) significantly (P ≤ 0.05) decreased. Results indicated that total essential amino acids of lentil seeds protein formed 38.10% of the total amino acid content. Sulfur-containing amino acids were the first limiting amino acid, while threonine was the second limiting amino acid in raw and germinated lentil seeds. Sprouting process has a positive effect on the essential amino acid contents and protein efficiency ratio (PER) of lentil sprouts. Phenolics content increased from 1341.13 mg/100 g DW in raw lentil seeds to 1411.50, 1463.00, 1630.20 and 1510.10 in those samples germinated for 3, 4, 5 and 6 days, respectively. Sprouted seeds had higher DPPH radical scavenging and reducing power activities. CONCLUSIONS: Based on these results, sprouting process is recommended to increase nutritive value, and antioxidant activity of lentil seeds.

Differential expression of structural genes for the late phase of phytic acid biosynthesis in developing seeds of wheat (Triticum aestivum L.).

In cereals, phytic acid (PA) or inositol hexakisphosphate (IP6) is a well-known phosphate storage compound as well as major chelator of important micronutrients (iron, zinc, calcium, etc.). Genes involved in the late phases of PA biosynthesis pathway are known in crops like maize, soybeans and barley but none have been reported from wheat. Our in silico analysis identified six wheat genes that might be involved in the biosynthesis of inositol phosphates. Four of the genes were inositol tetraphosphate kinases (TaITPK1, TaITPK2, TaITPK3, and TaITPK4), and the other two genes encode for inositol triphosphate kinase (TaIPK2) and inositol pentakisphosphate kinase (TaIPK1). Additionally, we identified a homolog of Zmlpa-1, an ABCC subclass multidrug resistance-associated transporter protein (TaMRP3) that is putatively involved in PA transport. Analyses of the mRNA expression levels of these seven genes showed that they are differentially expressed during seed development, and that some are preferentially expressed in aleurone tissue. These results suggest selective roles during PA biosynthesis, and that both lipid-independent and -dependent pathways are active in developing wheat grains. TaIPK1 and TaMRP3 were able to complement the yeast ScΔipk1 and ScΔycf1 mutants, respectively, providing evidence that the wheat genes have the expected biochemical functions. This is the first comprehensive study of the wheat genes involved in the late phase of PA biosynthesis. Knowledge generated from these studies could be utilized to develop strategies for generating low phyate wheat.

Induction of phytic acid synthesis by abscisic acid in suspension-cultured cells of rice.

A pathway of phytic acid (PA) synthesis in plants has been revealed via investigations of low phytic acid mutants. However, the regulation of this pathway is not well understood because it is difficult to control the environments of cells in the seeds, where PA is mainly synthesized. We modified a rice suspension culture system in order to study the regulation of PA synthesis. Rice cells cultured with abscisic acid (ABA) accumulate PA at higher levels than cells cultured without ABA, and PA accumulation levels increase with ABA concentration. On the other hand, higher concentrations of sucrose or inorganic phosphorus do not affect PA accumulation. Mutations in the genes RINO1, OsMIK, OsIPK1 and OsLPA1 have each been reported to confer low phytic acid phenotypes in seeds. Each of these genes is upregulated in cells cultured with ABA. OsITPK4 and OsITPK6 are upregulated in cells cultured with ABA and in developing seeds. These results suggest that the regulation of PA synthesis is similar between developing seeds and cells in this suspension culture system. This system will be a powerful tool for elucidating the regulation of PA synthesis.

Synthesis of inositol phosphate ligands of plant hormone-receptor complexes: pathways of inositol hexakisphosphate turnover.

Reduction of phytate is a major goal of plant breeding programs to improve the nutritional quality of crops. Remarkably, except for the storage organs of crops such as barley, maize and soybean, we know little of the stereoisomeric composition of inositol phosphates in plant tissues. To investigate the metabolic origins of higher inositol phosphates in photosynthetic tissues, we have radiolabelled leaf tissue of Solanum tuberosum with myo-[2-3H]inositol, undertaken a detailed analysis of inositol phosphate stereoisomerism and permeabilized mesophyll protoplasts in media containing inositol phosphates. We describe the inositol phosphate composition of leaf tissue and identify pathways of inositol phosphate metabolism that we reveal to be common to other kingdoms. Our results identify the metabolic origins of a number of higher inositol phosphates including ones that are precursors of cofactors, or cofactors of plant hormone-receptor complexes. The present study affords alternative explanations of the effects of disruption of inositol phosphate metabolism reported in other species, and identifies different inositol phosphates from that described in photosynthetic tissue of the monocot Spirodela polyrhiza. We define the pathways of inositol hexakisphosphate turnover and shed light on the occurrence of a number of inositol phosphates identified in animals, for which metabolic origins have not been defined.

Identification of genes necessary for wild-type levels of seed phytic acid in Arabidopsis thaliana using a reverse genetics approach.

The majority of phosphorus (P) in seeds is found in phytic acid (InsP(6)) which accumulates as the mixed salt phytate. InsP(6) is generally considered to be an anti-nutrient and the development of low phytic acid (lpa) seed crops is of significant interest. We have employed a reverse genetics approach to examine the impact of disrupting genes involved in inositol phosphate metabolism on Arabidopsis seed InsP(6) levels. Our analysis revealed that knockout mutations in three genes (AtITPK1, AtITPK4, and AtMIK/At5g58730) reduced seed InsP(6) in addition to knockouts of four previously reported genes (AtIPK1, AtIPK2ß, AtMRP5, and At5g60760). Seeds of these lpa mutants also exhibited reduced germination under various stress conditions. The greatest reduction in InsP(6) (>70%) was observed in atmrp5 seeds which were also among the least sensitive to the stresses examined. Expression analysis of the lpa genes revealed three distinct patterns in developing siliques consistent with their presumed roles. Disruption of each lpa gene resulted in changes in the expression in some of the other lpa genes indicating that transcription of lpa genes is modulated by other constituents of InsP(6) metabolism. While all the lpa genes represent possible targets for genetic engineering of low phytate seed crops, mutations in AtMRP5, AtMIK, and At5g60760 may be most successful for conventional approaches such as mutation breeding.

A defective ABC transporter of the MRP family, responsible for the bean lpa1 mutation, affects the regulation of the phytic acid pathway, reduces seed myo-inositol and alters ABA sensitivity.

• We previously identified the lpa1 (low phytic acid) 280-10 line that carries a mutation conferring a 90% reduction in phytic acid (InsP(6) ) content. In contrast to other lpa mutants, lpa1(280-10) does not display negative pleiotropic effects. In the present paper, we have identified the mutated gene and analysed its impact on the phytic acid pathway. • Here, we mapped the lpa1(280-10) mutation by bulk analysis on a segregating F(2) population, an then, by comparison with the soybean genome, we identified and sequenced a candidate gene. The InsP(6) pathway was analysed by gene expression and quantification of metabolites. • The mutated Pvmrp1(280-10) cosegregates with the lpa1(280-10) mutation, and the expression level of several genes of the InsP(6) pathway are reduced in the lpa1(280-10) mutant as well as the inositol and raffinosaccharide content. PvMrp2, a very similar paralogue of PvMrp1 was also mapped and sequenced. • The lpa1 mutation in beans is likely the result of a defective Mrp1 gene (orthologous to the lpa genes AtMRP5 and ZmMRP4), while its Mrp2 paralog is not able to complement the mutant phenotype in the seed. This mutation appears to down-regulate the InsP(6) pathway at the transcriptional level, as well as altering inositol-related metabolism and affecting ABA sensitivity.

Transcriptional profile of genes involved in the biosynthesis of phytate and ferritin in Coffea.

The present work aimed to study the control of the biosynthesis of the antinutritional factor phytate and its associated Fe-rich protein family, ferritin, in coffee. Phytate has the ability to chelate Fe, making it unavailable to human absorption. The Coffea genome databases were queried for genes associated with phytate metabolism and ferritin genes. The genetic framework for phytate biosynthesis and its reverse pathway was identified in silico analyses and indicate that Coffea phosphatidyl inositol kinase and monophosphatase families play nonredundant roles in phytate metabolism. The transcriptional profiles of phytate biosynthesis key-genes MYO-INOSITOL(3)P1 SYNTHASE, two genes coding for PHOSPHATIDYL INOSITOL KINASE, and three FERRITIN genes were temporally evaluated by qPCR in coffee seeds from two crop locations, Adamantina-SP and Ouro-Fino-MG, the last one traditionally associated with high-quality coffee beverage grain. A targeted metabolome profile of phytic acid contents throughout three fruit maturation stages in association with the transcriptional analysis was also obtained. Taken together, our data indicate that the investigated local conditions did not cause significant alterations in phytate biosynthesis. Futhermore, the temporal transcriptional profiling revealed that candidate gene expression is regulated independently of phytate accumulation. In contrast, the expression profile of ferritin-unit genes is affected by environmental conditions and genetic background. The roles of the investigated genes are discussed concerning the quality of coffee beverage.

Differential effects of a transgene to confer low phytic acid in caryopses located at different positions in rice panicles.

In previous studies, we attempted to reduce phytic acid in rice seeds by silencing the 1d-myo-inositol 3-phosphate synthase gene, RINO1, using an antisense sequence under the control of the rice glutelin GluB-1 promoter. The stable transgenic line showed a weak low phytic acid phenotype. In this study, we show that the position of the caryopsis in the panicle might affect the level of gene silencing through a difference in temporal and spatial expression patterns between RINO1 and GluB-1 promoters, resulting in a large variation in Pi levels and a small increase in Pi in the transgenic seeds.