Nitric oxide-mediated cytosolic glucose-6-phosphate dehydrogenase is involved in aluminum toxicity of soybean under high aluminum concentration

Aims

Glucose-6-phosphate dehydrogenase (G6PDH) has been reported to be involved in resistance to various environmental stresses. However, the role of G6PDH in aluminum (Al) toxicity remains unclear.

Methods

Physiological and biochemical methods together with histochemical analysis were used to investigate the participation of G6PDH in Al-induced inhibition of root growth.

Results

Exposure to high Al concentration caused a significant increase in the activities of total and cytosolic G6PDH in roots of soybean. Al-induced inhibition of root growth and oxidative stress were alleviated by a G6PDH inhibitor. Reactive oxygen species (ROS) accumulation in Al-treated root apexes could be abolished by a NADPH oxidase inhibitor. Furthermore, treatment with a G6PDH inhibitor reduced NADPH content and NADPH oxidase activity in Al-treated root apexes. Further investigation demonstrates that nitric oxide (NO) mediates Al-induced increase in cytosolic G6PDH activity by modulating the expression of genes encoding cytosolic G6PDH. In addition, nitrate reductase pathway is mainly responsible for Al-induced NO production in root apexes.

Conclusions

These results indicate that NADPH produced by NO-modulated cytosolic G6PDH in root apexes is responsible for ROS accumulation mediated by NADPH oxidase under Al stress, subsequently suffering from oxidative stress and thus causing the inhibition of root elongation.

     

Iridoid and phenylethanoid/phenylpropanoid metabolite profiles of <Emphasis Type="Italic">Scrophularia</Emphasis> and <Emphasis Type="Italic">Verbascum</Emphasis> species used medicinally in North America

Introduction

Botanicals containing iridoid and phenylethanoid/phenylpropanoid glycosides are used worldwide for the treatment of inflammatory musculoskeletal conditions that are primary causes of human years lived with disability, such as arthritis and lower back pain.

Objectives

We report the analysis of candidate anti-inflammatory metabolites of several endemic Scrophularia species and Verbascum thapsus used medicinally by peoples of North America.

Methods

Leaves, stems, and roots were analyzed by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) and partial least squares-discriminant analysis (PLS-DA) was performed in MetaboAnalyst 3.0 after processing the datasets in Progenesis QI.

Results

Comparison of the datasets revealed significant and differential accumulation of iridoid and phenylethanoid/phenylpropanoid glycosides in the tissues of the endemic Scrophularia species and Verbascum thapsus.

Conclusions

Our investigation identified several species of pharmacological interest as good sources for harpagoside and other important anti-inflammatory metabolites.

     

Effects of silicon on aluminum toxicity in upland rice plants

Aims

This study aimed to determine the capacity of Si to mitigate Al toxicity in upland rice plants (Oryza sativa L.) by evaluating plant growth and the Si and Al uptake kinetics.

Methods

Plants were grown for 40 days, after which the Si and Al uptake kinetics (Cmin, Km and Imax) were analyzed. Then, the shoots and roots were separated, and the dry matter, root morphology and Si and Al concentration and accumulation in the plant were evaluated.

Results

Aluminum decreased plant growth and the Si uptake capacity by decreasing the root growth and Si transport system efficiency in the upland rice roots (> Km and > Cmin). Silicon mitigated Al toxicity in the upland rice plants by decreasing Al transport to the plant shoots, although it did not reduce the Al uptake rate (Imax). Si treatment increased the growth of upland rice plant shoots grown in the presence of Al without influencing the root growth. The alleviation of Al toxicity by Si is more evident in the susceptible upland rice cultivar Maravilha.

Conclusions

Silicon mitigated Al toxicity in the upland rice plants by decreasing Al transport to the plant shoots but did not reduce the Al uptake rate by roots.

     

Anchoring quartet-based phylogenetic distances and applications to species tree reconstruction

Background

Inferring species trees from gene trees using the coalescent-based summary methods has been the subject of much attention, yet new scalable and accurate methods are needed.

Results

We introduce DISTIQUE, a new statistically consistent summary method for inferring species trees from gene trees under the coalescent model. We generalize our results to arbitrary phylogenetic inference problems; we show that two arbitrarily chosen leaves, called anchors, can be used to estimate relative distances between all other pairs of leaves by inferring relevant quartet trees. This results in a family of distance-based tree inference methods, with running times ranging between quadratic to quartic in the number of leaves.

Conclusions

We show in simulated studies that DISTIQUE has comparable accuracy to leading coalescent-based summary methods and reduced running times.

     

Differential elemental uptake in three pseudo-metallophyte C<Subscript>4</Subscript> grasses in situ in the eastern USA

Background and aims

Elemental uptake in serpentine floras in eastern North America is largely unknown. The objective of this study was to determine major and trace element concentrations in soil and leaves of three native pseudo-metallophyte C₄ grasses in situ at five sites with three very different soil types, including three serpentine sites, in eastern USA.

Methods

Pseudo-total and extractible concentrations of 15 elements were measured and correlated from the soils and leaves of three species at the five sites.

Results

Element concentrations in soils of pseudo-metallophytes varied up to five orders of magnitude. Soils from metalliferous sites exhibited higher concentrations of their characteristic elements than non-metalliferous. In metallicolous populations, elemental concentrations depended on the element. Concentrations of major elements (Ca, Mg, K) in leaves were lower than typical toxicity thresholds, whereas concentrations of Zn were higher.

Conclusions

In grasses, species can maintain relatively low metal concentrations in their leaves even when soil concentrations are richer. However, in highly Zn-contaminated soil, we found evidence of a threshold concentration above which Zn uptake increases drastically. Finally, absence of main characteristics of serpentine soil at one site indicated the importance of soil survey and restoration to maintain serpentinophytes communities and avoid soil encroachment.

     

Optimization of fecal sample preparation for untargeted LC-HRMS based metabolomics

Introduction

Collecting feces is easy. It offers direct outcome to endogenous and microbial metabolites.

Objectives

In a context of lack of consensus about fecal sample preparation, especially in animal species, we developed a robust protocol allowing untargeted LC-HRMS fingerprinting.

Methods

The conditions of extraction (quantity, preparation, solvents, dilutions) were investigated in bovine feces.

Results

A rapid and simple protocol involving feces extraction with methanol (1/3, M/V) followed by centrifugation and a step filtration (10 kDa) was developed.

Conclusion

The workflow generated repeatable and informative fingerprints for robust metabolome characterization.

     

Silicon acquisition by bananas (c.V. Grande Naine) is increased in presence of the arbuscular mycorrhizal fungus <Emphasis Type="Italic">Rhizophagus irregularis</Emphasis> MUCL 41833

Aim

This work aimed to investigate the role of arbuscular mycorrhizal fungi (AMF) in the uptake and accumulation of silicon (Si) in banana plants. Si is recognized as a significant element that helps plants resist stresses.

Methods

A pot experiment compared the growth, Si and P accumulation of banana plants pre-colonized or not by an AMF and exposed or not to Si added to the growth substrate.

Results

A marked increase in Si was noticed in pseudostem, leaves and roots of pre-colonized banana plants, in presence as well as in absence of Si added to the growth substrate. Without Si addition, this accumulation was 60 % and 45 % higher in pseudostem and leaves, respectively, while it was 47 % and 41 % in presence of Si added to the substrate. In roots, this increase was 23 % and 52 % in presence and absence of Si added to the substrate, respectively. Phosphorus content in shoots and roots was likewise significantly increased in presence of AMF or Si.

Conclusion

Our findings revealed that pre-colonized banana plants accumulated more Si in shoot and roots than non-mycorrhizal plants and may thus represent a potential novel avenue to explore banana resistance to pests and diseases.

     

Physiological and molecular analysis of aluminum tolerance in selected Kenyan maize lines

Aims

Aluminum (Al) toxicity is an important limitation to maize production in many tropical and sub-tropical acid soil areas. The aim of this study was to survey the variation in Al tolerance in a panel of maize lines adapted for Kenya and look for novel sources of Al tolerance.

Methods

112 Kenyan maize accessions were phenotyped for Al tolerance in solution culture. Several Al tolerance-related parameters including relative net root growth (RNRG), root apex Al accumulation, Al-activated root organic acid exudation, and expression of the maize Al tolerance gene, ZmMATE1, were used to classify Kenyan maize accessions.

Results

Based on RNRG, 42 %, 28 %, and 30 % of the lines were classified as highly tolerant, moderately tolerant and sensitive, respectively. Tolerant accessions accumulated less Al in their root apices compared to sensitive lines. The Kenyan maize line, CON 5, and the Brazilian standard for tolerance, Cateto, exhibited the greatest Al tolerance based on RNRG, but CON 5 had only about 50 % of ZmMATE1 gene expression relative to Cateto. CON 5 also had low root apex Al content and high citrate exudation, suggesting that it may employ a citrate transporter other than ZmMATE1.

Conclusions

We identified a very Al tolerant Kenyan maize line whose Al tolerance may be based in part on a novel tolerance gene. The maize lines identified in this study are useful germplasm for the development of varieties suitable for agriculture on acid soils in Kenya.

     

The contrasting effects of nutrient enrichment on growth,biomass allocation and decomposition of plant tissue in coastal wetlands

Background

Most studies focus on macronutrient of C, N and P and ignore other elements, which restrict our understanding on the strategy of plant nutrient adaption and nutrient cycling.

Methods

We investigated 14 element (C, N, P, S, K, Ca, Mg, Fe, Mn, Zn, Cu, Na, Al, and Ba) concentrations of green and senesced leaves in Quercus variabilis along the altitude in the Baotianman Mountains, China, and assessed their relationships with climate, soil, and plant functional traits.

Results

Leaf N,S and K increased with, C, Ca, Na, Fe, Mn, Cu and Ba decreased with, and P, Mg, Al, Zn and N:P did not change significantly with altitude. NRE and SRE increased with, and CRE decreased with altitude (p < 0.05). Among the 14 elements, nucleic acid-protein elements (N, K, S and P) were resorbed preferentially, compare to structural (Ca, Mn, and B) and enzymatic (C, Cu, Mg and Zn) that were discriminated against, and toxic (Al and Fe) elements that were totally excluded.

Conclusions

Q. variabilis can synergetically regulate green leaf multielement stoichiometry and nutrient resorption in responses to environment change. Deciduous plants may have a trade-off mechanism at the end of growing season to rebalance somatic nutrients.

     

Accumulation of Fascin<Superscript>+</Superscript> cells during experimental autoimmune neuritis

Background

Experimental autoimmune neuritis (EAN) is a well-known animal model of human demyelinating polyneuropathies and is characterized by inflammation and demyelination in the peripheral nervous system. Fascin is an evolutionarily highly conserved cytoskeletal protein of 55 kDa containing two actin binding domains that cross-link filamentous actin to hexagonal bundles.

Methods

Here we have studied by immunohistochemistry the spatiotemporal accumulation of Fascin?+?cells in sciatic nerves of EAN rats.

Results

A robust accumulation of Fascin?+?cell was observed in the peripheral nervous system of EAN which was correlated with the severity of neurological signs in EAN.

Conclusion

Our results suggest a pathological role of Fascin in EAN.

Virtual slides

The virtual slides for this article can be found here: http://www.diagnosticphatology.diagnomx.eu/vs/6734593451114811

     

The use of metabolome analysis to identify the cause of an unexplained disease of Japanese gentians (<Emphasis Type="Italic">Gentiana triflora</Emphasis>)

Introduction

Gentian spotted bleaching disease (GSBD), a novel disease of unknown etiology, affects Gentiana triflora plants that are cultivated as ornamental flowers in Japan. This disease leads to the production of necrotic leaf spots, a delay in flowering, and has thus become a serious problem for gentian production.

Objectives

The objective of this study was to identify the cause of GSBD in G. triflora by analyzing differences between healthy and GSBD-affected leaves.

Method

Selected metabolite concentrations in healthy and GSBD-affected leaves were quantified using capillary electrophoresis and liquid chromatography-mass spectrometry, and statistically significant differences in metabolite concentrations were assessed. GSBD-affected metabolic pathways were identified followed by examination of pathway-related gene expression and enzyme activities. Furthermore, the effects of root hypoxia on metabolite concentrations and gene expression were investigated.

Results

We found that concentrations of Calvin cycle intermediates and ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) activity were significantly lower in GSBD-affected leaves, whereas sucrose cleavage and Ala accumulation were enhanced. Since these metabolic changes are frequently observed in plants exposed to hypoxia, the expression of hypoxia-responsive genes was investigated. Expression levels of hypoxia-responsive genes were higher in GSBD-affected plants than in the controls. Furthermore, root hypoxia induced similar symptoms and metabolic changes as those observed in GSBD-affected plants.

Conclusion

Our results indicate that GSBD was likely induced by root hypoxia and that metabolome analysis is an effective tool for identifying the cause of plant disease with unknown etiologies.

     

A lost opportunity for science: journals promote data sharing in metabolomics but do not enforce it

Introduction

Data sharing is being increasingly required by journals and has been heralded as a solution to the ‘replication crisis’.

Objectives

(i) Review data sharing policies of journals publishing the most metabolomics papers associated with open data and (ii) compare these journals’ policies to those that publish the most metabolomics papers.

Methods

A PubMed search was used to identify metabolomics papers. Metabolomics data repositories were manually searched for linked publications.

Results

Journals that support data sharing are not necessarily those with the most papers associated to open metabolomics data.

Conclusion

Further efforts are required to improve data sharing in metabolomics.

     

Comparative effect of inorganic N on plant growth and N<Subscript>2</Subscript> fixation of ten legume crops: towards a better understanding of the differential response among species

Aims

A better understanding of how plant growth, N nutrition and symbiotic nitrogen fixation (SNF) are influenced by soil inorganic N availability, for a wide range of legume species, is crucial to optimise legume productivity, N₂ fixation, while limiting environmental risks such as N leaching.

Methods

A comparative analysis was performed for ten legume crops, grown in a field experiment and supplied with four N fertiliser rates. Dry matter, N concentration and SNF were measured. In parallel, root elongation rates were studied in a greenhouse experiment.

Results

For most species, N fertilisation had little effect on plant growth and N accumulation. SNF was reduced by soil inorganic N available at sowing but with large differences in the magnitude of the response among species. The response varied according to plant N requirements for growth and plant ability to retrieve inorganic N. Accordingly, root lateral expansion rate measured in RhizoTubes was highly correlated with plant ability to retrieve inorganic N measured in the field experiment.

Conclusion

Combining SNF response to soil inorganic N, shoot N and plant ability to retrieve inorganic N, allowed a robust evaluation of differential response to soil inorganic N among a wide range of legume species.

     

Pseudo current density maps of electrophysiological heart,nerve or brain function and their physical basis

Background

In recent years the visualization of biomagnetic measurement data by so-called pseudo current density maps or Hosaka-Cohen (HC) transformations became popular.

Methods

The physical basis of these intuitive maps is clarified by means of analytically solvable problems.

Results

Examples in magnetocardiography, magnetoencephalography and magnetoneurography demonstrate the usefulness of this method.

Conclusion

Hardware realizations of the HC-transformation and some similar transformations are discussed which could advantageously support cross-platform comparability of biomagnetic measurements.

     

Inter- and intra-species intercropping of barley cultivars and legume species,as affected by soil phosphorus availability

Aims

Intercropping can improve plant yields and soil phosphorus (P) use efficiency. This study compares inter- and intra-species intercropping, and determines whether P uptake and shoot biomass accumulation in intercrops are affected by soil P availability.

Methods

Four barley cultivars (Hordeum vulgare L.) and three legume species (Trifolium subterreneum, Ornithopus sativus and Medicago truncatula) were selected on the basis of their contrasting root exudation and morphological responses to P deficiency. Monocultures and barley-barley and barley-legume intercrops were grown for 6 weeks in a pot trial at very limiting, slightly limiting and excess available soil P. Above-ground biomass and shoot P were measured.

Results

Barley-legume intercrops had 10–70% greater P accumulation and 0–40% greater biomass than monocultures, with the greatest gains occurring at or below the sub-critical P requirement for barley. No benefit of barley-barley intercropping was observed. The plant combination had no significant effect on biomass and P uptake observed in intercropped treatments.

Conclusions

Barley-legume intercropping shows promise for sustainable production systems, especially at low soil P. Gains in biomass and P uptake come from inter- rather than intra-species intercropping, indicating that plant diversity resulted in decreased competition between plants for P.

     

Asymmetric effects of litter removal and litter addition on the structure and function of soil microbial communities in a managed pine forest

Aims

The effect of different MeJA doses applied prior to or simultaneously with toxic Al on biochemical and physiological properties of Vaccinium corymbosum cultivars with contrasting Al resistance was studied.

Methods

Legacy (Al-resistant) and Bluegold (Al-sensitive) plants were treated with and without toxic Al under controlled conditions: a) without Al and MeJA, b) 100 μM Al, c) 100 μM Al + 5 μM MeJA, d) 100 μM Al + 10 μM MeJA and e) 100 μM Al + 50 μM MeJA. MeJA was applied to leaves 24 h prior to or simultaneously with Al in nutrient solution. After 48 h, Al-concentration, lipid peroxidation (LP), H₂O₂, antioxidant activity, total phenols, total flavonoids, phenolic compounds and superoxide dismutase activity (SOD) of plant organs were analyzed.

Results

Al-concentrations increased with Al-treatment in both cultivars, being Al, LP and H₂O₂ concentrations reduced with low simultaneous MeJA application. Higher MeJA doses induced more oxidative damage than the lowest. Legacy increased mainly non-enzymatic compounds, whereas Bluegold increased SOD activity to counteract Al³⁺.

Conclusions

Low MeJA doses applied simultaneously with Al³⁺ increased Al-resistance in Legacy by increasing phenolic compounds, while Bluegold reduced oxidative damage through increment of SOD activity, suggesting a diminution of its Al-sensitivity. Higher MeJA doses could be potentially toxic. Studies are needed to determine the molecular mechanisms involved in the protective MeJA effect against Al-toxicity.

     

Metabolic adaptation following genome doubling in citrus doubled diploids revealed by non-targeted metabolomics

Introduction

Polyploidy is a widespread phenomenon in nature and is thought to play a major role in the evolution of flowering plants. Additionally, polyploidization produces novel phenotypes that through plant breeding have enhanced the production of biomass and improved the stress tolerance of major economic crops. However, the effect of polyploidization on plant metabolism is still unclear.

Objectives

In order to test whether there are common metabolic responses following genome doubling, we performed a comparative metabolomic analysis of mature leaves from doubled diploids and the corresponding diploids of red tangerine (Citrus reticulata Blanco), trifoliate orange (Poncirus trifoliata L. Raf.) and precocious trifoliate orange (P. trifoliata).

Methods

Non-targeted and targeted metabolic profiling of mature leaves from three doubled diploids and their diploid controls were performed by using liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS) and gas chromatography–mass spectrometry (GC–MS).

Results

About 11–34% of the detected metabolic features differentially accumulated in the doubled diploids, mostly by less than fivefold. The levels of primary metabolites tended to increase in the doubled diploids. Concentrations of tricarboxylic acid cycle intermediates—citric acid, malic acid, fumaric acid and succinic acid, enhanced in all of the doubled diploids. The levels of secondary metabolites, including phenylpropanoids and terpenoids, tended to decrease in the doubled diploids. This is consistent with the lower C/N ratios in the doubled diploids.

Conclusions

Polyploidization had a significant but relatively limited influence on the accumulation of metabolites in these citrus species. We conclude that primary metabolism takes priority over secondary metabolism in doubled diploid plants to relieve the “genomic stress” encountered during the early stages of genome doubling, probably to promote vitality and growth.

     

An efficient method for medium throughput screening of cuticular wax composition in different plant species

Introduction

Most aerial plant organs are covered by a cuticle, which largely consists of cutin and wax. Cuticular waxes are mixtures of dozens of compounds, mostly very-long-chain aliphatics that are easily extracted by solvents. Over the last four decades, diverse cuticular wax analysis protocols have been developed, most of which are complex and time-consuming, and need to be adapted for each plant species or organ. Plant genomics and breeding programs often require mid-throughput metabolic phenotyping approaches to screen large numbers of individuals and obtain relevant biological information.

Objectives

To generate a fast, simple and user-friendly methodology able to capture most wax complexity independently of the plant, cultivar and organ.

Methods

Here we present a simple GC–MS method for screening relatively small wax amounts, sampled by short extraction with a versatile, uniform solvent. The method will be tested and validated in leaves and fruits from three different crop species: tomato (Solanum lycopersicum), apple (Malus domestica) and hybrid aspen (Populus tremula × tremuloides).

Results

Consistent results were obtained in tomato cultivar M82 across three consecutive years (2010–2012), two organs (leaf and fruit), and also in two different tomato (M82 and MicroTom) and apple (Golden Delicious and Granny Smith) cultivars. Our results on tomato wax composition match those reported previously, while our apple and hybrid aspen analyses provide the first comprehensive cuticular wax profile of these species.

Conclusion

This protocol allows standardized identification and quantification of most cuticular wax components in a range of species.

     

Variation of the microbiota and metabolome along the canine gastrointestinal tract

Introduction

The fecal microbiota are relevant to the health and disease of many species. The importance of the fecal metabolome has more recently been appreciated, but our knowledge of the microbiota and metabolome at other sites along the gastrointestinal tract remains deficient.

Objective

To analyze the gastrointestinal microbiota and metabolome of healthy domestic dogs at four anatomical sites.

Methods

Samples of the duodenal, ileal, colonic, and rectal contents were collected from six adult dogs after humane euthanasia for an unrelated study. The microbiota were characterized using Illumina sequencing of 16S rRNA genes. The metabolome was characterized by mass spectrometry-based methods.

Results

Prevalent phyla throughout the samples were Proteobacteria, Firmicutes, Fusobacteria, and Bacteroidetes, consistent with previous findings in dogs and other species. A total of 530 unique metabolites were detected; 199 of these were identified as previously named compounds, but 141 of them had at least one significantly different site-pair comparison. Noteworthy examples include relative concentrations of amino acids, which decreased from the small to large intestine; pyruvate, which peaked in the ileum; and several phenol-containing carboxylic acid compounds that increased in the large intestine.

Conclusion

The microbiota and metabolome vary significantly at different sites along the canine gastrointestinal tract.