Barley (Hordeum vulgare) oxalate oxidase is a manganese-containing enzyme.
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ABSTRACT:
SUBMITTER: Requena L
PROVIDER: S-EPMC1220540 | biostudies-other | 1999 Oct
REPOSITORIES: biostudies-other
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Project description:The food enzyme considered in this opinion is a 4-?-d-glucan maltohydrolase (EC 3.2.1.2) obtained from grain of barley (Hordeum vulgare), by the companies Genencor International B.V. and Senson Oy. This ?-amylase is intended to be used in several food-manufacturing processes: baking and brewing processes, distilled alcohol production, and starch processing for the production of glucose syrups. The compositional data provided for the food enzyme were considered sufficient. The manufacturing process did not raise safety concerns. Based on the maximum use levels recommended for the respective food processes, dietary exposure to the food enzyme-total organic solids (TOS) was estimated on the basis of individual data from the EFSA Comprehensive European Food Consumption Database. This exposure estimate is similar to or lower than the exposure to a fraction of barley comparable to the food enzyme-TOS, resulting from the consumption of barley-derived foods. As the food enzyme is derived from edible parts of barley, in line with the requirements of the guidance document on food enzyme assessment, the Panel accepted that there was no need for the provision of toxicological data for this food enzyme and the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use. Considering the potential for allergenicity, the gluten content of the food enzyme was below the detection limit of the analytical method, which is well below the level of 20 mg/kg for 'gluten-free' products. The amino acid sequence of the ?-amylase was compared to those of known allergens and no match was found. The food enzyme ?-amylase from barley is an occupational respiratory allergen and may contain low levels of other allergenic barley proteins that may trigger adverse reactions upon oral challenges in individuals with an oral sensitisation to cereals. The Panel considers that dietary exposure to the food enzyme ?-amylase from barley may result in incidental cases of food allergic reactions.
| S-EPMC7009815 | biostudies-literature
Project description:Background and aimsManganese (Mn) deficiency in barley is a global problem. It is difficult to detect in the early stages of symptom development and is commonly pre-emptively corrected by Mn foliar sprays that can be costly. Landraces adapted to marginal lands around the world represent a genetic resource for potential sustainability traits including mineral use efficiency. This research aims to confirm novel Mn use efficiency traits from the Scottish landrace Bere and use an association mapping approach to identify genetic loci associated with the trait.MethodsA hydroponic system was developed to identify and characterize the Mn deficiency tolerance traits in a collection of landraces, including a large number of Scottish Bere barleys, a group of six-rowed heritage landraces grown in the highlands and islands of Scotland. Measuring chlorophyll fluorescence, the effect of Mn deficiency was identified in the early stages of development. Genotypic data, generated using the 50k Illumina iSelect genotyping array, were coupled with the Mn phenotypic data to create a genome-wide association study (GWAS) identifying candidate loci associated with Mn use efficiency.Key resultsThe Bere lines generally had good Mn use efficiency traits. Individual Bere lines showed large efficiencies, with some Bere lines recording almost double chlorophyll fluorescence readings in limited Mn conditions compared with the elite cultivar Scholar. The Mn-efficient Bere lines had increased accumulation of Mn in their shoot biomass compared with elite cultivars, which was highly correlated to the chlorophyll fluorescence. Several candidate genes were identified as being associated with Mn use efficiency in the GWAS.ConclusionsSeveral genomic regions for Mn use efficiency traits originating from the Bere lines were identified. Further examination and validation of these regions should be undertaken to identify candidate genes for future breeding for marginal lands.
| S-EPMC7380464 | biostudies-literature
Project description:Gene expression in plastids of higher plants is dependent on two different transcription machineries, a plastid-encoded bacterial-type RNA polymerase (PEP) and a nuclear-encoded phage-type RNA polymerase (NEP), which recognize distinct types of promoters. The division of labor between PEP and NEP during plastid development and in mature chloroplasts is unclear due to a lack of comprehensive information on promoter usage. Here we present a thorough investigation into the distribution of PEP and NEP promoters within the plastid genome of barley (Hordeum vulgare L). Using a novel differential RNA sequencing approach, which discriminates between primary and processed transcripts, we obtained a genome-wide map of transcription start sites in plastids of mature first leaves. PEP-lacking plastids of the albostrians mutant allowed for the unambiguous identifications of NEP promoters. We observed that the chloroplast genome contains many more promoters than genes. According to our data, most genes (including genes coding for photosynthesis proteins) have both PEP and NEP promoters. We also detected numerous transcription start sites within operons indicating transcriptional uncoupling of genes in polycistronic gene clusters. Moreover, we mapped many transcription start sites in intergenic regions, as well as opposite to annotated genes demonstrating the existence of numerous non-coding RNA candidates.
2011-11-23 | GSE33773 | GEO
Project description:Polyphenol oxidase (PPO) is an oxidoreductase. In damaged plant tissues, it catalyzes enzymatic browning by oxidizing o-diphenols to highly reactive o-quinones, which polymerize producing heterogeneous dark polymer melanin. In intact tissues, functions of PPO are not well understood. The aim of the study was to investigate the barley PPO gene family and to reveal the possible involvement of Ppo genes in melanization of barley grain, which is controlled by the Blp1 gene. Based on known barley Ppo genes on chromosome 2H (Ppo1 and Ppo2), two additional genes-Ppo3 and Ppo4-were found on chromosomes 3H and 4H, respectively. These genes have one and two exons, respectively, contain a conserved tyrosinase domain and are thought to be functional. Comparative transcriptional analyzes of the genes in samples of developing grains (combined hulls and pericarp tissues) were conducted in two barley lines differing by melanin pigmentation. The genes were found to be transcribed with increasing intensity (while grains mature) independently from the grain color, except for Ppo2, which is transcribed only in black-grained line i:BwBlp1 accumulating melanin in grains. Analysis of this gene's expression in detached hulls and pericarps showed its elevated transcription in both tissues in comparison with yellow ones, while it was significantly higher in hulls than in pericarp. Segregation analysis in two F2 populations obtained based on barley genotypes carrying dominant Blp1 and recessive ppo1 (I) and dominant Blp1 and recessive ppo1 and ppo2 (II) was carried out. In population I, only two phenotypic classes corresponding to parental black and white ones were observed; the segregation ratio was 3 black to 1 white, corresponding to monogenic. In population II, aside from descendants with black and white grains, hybrids with a gray phenotype - light hulls and dark pericarp - were observed; the segregation ratio was 9 black to 3 gray to 4 white, corresponding to the epistatic interaction of two genes. Most hybrids with the gray phenotype carry dominant Blp1 and a homozygous recessive allele of Ppo2. Based on transcription and segregation assays one may conclude involvement of Ppo2 but not Ppo1 in melanin formation in barley hulls.
| S-EPMC10800887 | biostudies-literature
Project description:Background and aimsResearch on manganese (Mn) toxicity and tolerance indicates that Mn toxicity develops apoplastically through increased peroxidase activities mediated by phenolics and Mn, and Mn tolerance could be conferred by sequestration of Mn in inert cell compartments. This comparative study focuses on Mn-sensitive barley (Hordeum vulgare) and Mn-tolerant rice (Oryza sativa) as model organisms to unravel the mechanisms of Mn toxicity and/or tolerance in monocots.MethodsBulk leaf Mn concentrations as well as peroxidase activities and protein concentrations were analysed in apoplastic washing fluid (AWF) in both species. In rice, Mn distribution between leaf compartments and the leaf proteome using 2D isoelectric focusing IEF/SDS-PAGE and 2D Blue native BN/SDS-PAGE was studied.Key resultsThe Mn sensitivity of barley was confirmed since the formation of brown spots on older leaves was induced by low bulk leaf and AWF Mn concentrations and exhibited strongly enhanced H2O2-producing and consuming peroxidase activities. In contrast, by a factor of 50, higher Mn concentrations did not produce Mn toxicity symptoms on older leaves in rice. Peroxidase activities, lower by a factor of about 100 in the rice leaf AWF compared with barley, support the view of a central role for these peroxidases in the apoplastic expression of Mn toxicity. The high Mn tolerance of old rice leaves could be related to a high Mn binding capacity of the cell walls. Proteomic studies suggest that the lower Mn tolerance of young rice leaves could be related to Mn excess-induced displacement of Mg and Fe from essential metabolic functions.ConclusionsThe results provide evidence that Mn toxicity in barley involves apoplastic lesions mediated by peroxidases. The high Mn tolerance of old leaves of rice involves a high Mn binding capacity of the cell walls, whereas Mn toxicity in less Mn-tolerant young leaves is related to Mn-induced Mg and Fe deficiencies.
| S-EPMC2887067 | biostudies-literature
Project description:The aleurone is a critical component of the cereal seed and is located at the periphery of the starchy endosperm. During germination, the aleurone is responsible for releasing hydrolytic enzymes that degrade cell wall polysaccharides and starch granules, which is a key requirement for barley malt production. Inter- and intra-species differences in aleurone layer number have been identified in the cereals but the significance of this variation during seed development and germination remains unclear. In this study, natural variation in mature aleurone features was examined in a panel of 33 Hordeum vulgare (barley) genotypes. Differences were identified in the number of aleurone cell layers, the transverse thickness of the aleurone and the proportion of aleurone relative to starchy endosperm. In addition, variation was identified in the activity of hydrolytic enzymes that are associated with germination. Notably, activity of the free fraction of ?-amylase (BMY), but not the bound fraction, was increased at grain maturity in barley varieties possessing more aleurone. Laser capture microdissection (LCM) and transcriptional profiling confirmed that HvBMY1 is the most abundant BMY gene in developing grain and accumulates in the aleurone during early stages of grain fill. The results reveal a link between molecular pathways influencing early aleurone development and increased levels of free ?-amylase enzyme, potentially highlighting the aleurone as a repository of free ?-amylase at grain maturity.
| S-EPMC6056469 | biostudies-literature
Project description:BACKGROUND: Endogenous phytase plays a crucial role in phytate degradation and is thus closely related to nutrient efficiency in barley products. The understanding of genetic information of phytase in barley can provide a useful tool for breeding new barley varieties with high phytase activity. METHODOLOGY/PRINCIPAL FINDINGS: Quantitative trait loci (QTL) analysis for phytase activity was conducted using a doubled haploid population. Phytase protein was purified and identified by the LC-ESI MS/MS Shotgun method. Purple acid phosphatase (PAP) gene was sequenced and the position was compared with the QTL controlling phytase activity. A major QTL for phytase activity was mapped to chromosome 5 H in barley. The gene controlling phytase activity in the region was named as mqPhy. The gene HvPAP a was mapped to the same position as mqPhy, supporting the colinearity between HvPAP a and mqPhy. CONCLUSIONS/SIGNIFICANCE: It is the first report on QTLs for phytase activity and the results showed that HvPAP a, which shares a same position with the QTL, is a major phytase gene in barley grains.
| S-EPMC3080886 | biostudies-literature
Project description:BackgroundSequencing analysis of mitochondrial genomes is important for understanding the evolution and genome structures of various plant species. Barley is a self-pollinated diploid plant with seven chromosomes comprising a large haploid genome of 5.1 Gbp. Wild barley (Hordeum vulgare ssp. spontaneum) and cultivated barley (H. vulgare ssp. vulgare) have cross compatibility and closely related genomes, although a significant number of nucleotide polymorphisms have been reported between their genomes.ResultsWe determined the complete nucleotide sequences of the mitochondrial genomes of wild and cultivated barley. Two independent circular maps of the 525,599 bp barley mitochondrial genome were constructed by de novo assembly of high-throughput sequencing reads of barley lines H602 and Haruna Nijo, with only three SNPs detected between haplotypes. These mitochondrial genomes contained 33 protein-coding genes, three ribosomal RNAs, 16 transfer RNAs, 188 new ORFs, six major repeat sequences and several types of transposable elements. Of the barley mitochondrial genome-encoded proteins, NAD6, NAD9 and RPS4 had unique structures among grass species.ConclusionsThe mitochondrial genome of barley was similar to those of other grass species in terms of gene content, but the configuration of the genes was highly differentiated from that of other grass species. Mitochondrial genome sequencing is essential for annotating the barley nuclear genome; our mitochondrial sequencing identified a significant number of fragmented mitochondrial sequences in the reported nuclear genome sequences. Little polymorphism was detected in the barley mitochondrial genome sequences, which should be explored further to elucidate the evolution of barley.
| S-EPMC5078923 | biostudies-literature
Project description:It is not known to what degree aquaporin-facilitated water uptake differs between root developmental regions and types of root. The aim of this study was to measure aquaporin-dependent water flow in the main types of root and root developmental regions of 14- to 17-d-old barley plants and to identify candidate aquaporins which mediate this flow. Water flow at root level was related to flow at cell and plant level. Plants were grown hydroponically. Hydraulic conductivity of cells and roots was determined with a pressure probe and through exudation, respectively, and whole-plant water flow (transpiration) determined gravimetrically in response to the commonly used aquaporin inhibitor HgCl(2). Expression of aquaporins was analysed by real-time PCR and in situ hybridization. Hydraulic conductivity of cortical cells in seminal roots was largest in lateral roots; it was smallest in the fully mature zone and intermediate in the not fully mature 'transition' zone along the main root axis. Adventitious roots displayed an even higher (3- to 4-fold) cortical cell hydraulic conductivity in the transition zone. This coincided with 3- to 4-fold higher expression of three aquaporins (HvPIP2;2, HvPIP2;5, HvTIP1:1). These were expressed (also) in cortical tissue. The largest inhibition of water flow (83-95%) in response to HgCl(2) was observed in cortical cells. Water flow through roots and plants was reduced less (40-74%). It is concluded that aquaporins contribute substantially to root water uptake in 14- to 17-d-old barley plants. Most water uptake occurs through lateral roots. HvPIP2;5, HvPIP2;2, and HvTIP1;1 are prime candidates to mediate water flow in cortical tissue.
| S-EPMC3153672 | biostudies-literature
Project description:Production of homozygous lines derived from transgenic plants is one of the important steps for phenotyping and genotyping transgenic progeny. The selection of homozygous plants is a tedious process that can be significantly shortened by androgenesis, cultivation of anthers, or isolated microspores. Doubled haploid (DH) production achieves complete homozygosity in one generation. We obtained transgenic homozygous DH lines from six different transgenic events by using anther culture. Anthers were isolated from T0 transgenic primary regenerants and cultivated in vitro. The ploidy level was determined in green regenerants. At least half of the 2n green plants were transgenic, and their progeny were shown to carry the transgene. The process of dihaploidization did not affect the expression of the transgene. Embryo cultures were used to reduce the time to seed of the next generation. The application of these methods enables rapid evaluation of transgenic lines for gene function studies and trait evaluation.
| S-EPMC7412030 | biostudies-literature