Beneficial role of endophytes in biofortification of Zn in wheat genotypes varying in nutrient use efficiency grown in soils sufficient and deficient in Zn

Background and aim

Most of the food grains show deficiency of zinc. The study was carried out to evaluate the role of endophytes in the fortification of Zn in wheat genotypes with different nutrient use efficiency and in soils deficient and sufficient for Zn.

Methods

Two zinc solubilizing endophytes (Bacillus subtilis DS-178 and Arthrobacter sp. DS-179) were used to inoculate low and high Zn accumulating genotypes in soils sufficient and deficient in Zn.

Results

The data on different root morphological parameters, yield and accumulation of Zn indicated distinct variations among genotypes; soil types and also among the endophytes inoculated, un-inoculated and chemical fertilizer treatments. In general, the amount of Zn in grains due to inoculation of endophytes was 2 folds higher as compared to un-inoculated control. The low and high Zn accumulating genotypes responded in an almost identical manner to endophyte inoculation, irrespective of the soil types.

Conclusion

Zn solubilizing endophytes can enhance the translocation and enrichment of Zn to grains in wheat genotypes, irrespective of their different nutrient use efficiency (Zn). This approach can be integrated into the modern strategies for biofortification.

     

Boreal forest plant species responses to pH: ecological interpretation and application to reclamation

Aims

Reclamation following oil sands mining in northeastern Alberta (Canada) creates adverse reforestation soil conditions, including extreme pH values. We elucidated pH tolerance limits of boreal plant species and how pH affects nutrient uptake in these plants.

Methods

We measured growth, gas exchange, and foliar nutrient concentration of 15 common northern boreal forest plants after eight weeks exposure to root zone pH ranging from 5.0 to 9.0. Cluster analyses were used to group these species based on their pH responses.

Results

Based on their growth and gas exchange responses to pH, the 15 plant species could be divided into five groups, each of which contained species that commonly co-occur in particular boreal forest site types. For the foliar nutrient responses to pH, the 15 species could be grouped into only two categories; both showed decreases in foliar N, P, Fe and Zn concentration with increasing pH, with a more pronounced effect on the group that included trembling aspen, paper birch and chokecherry.

Conclusions

The evidence of differential adaptation to pH by habitat type suggests the importance of soil pH as a factor affecting boreal plant species distribution and could be helpful for selection of species suitable for reclamation of sites with altered soil pH.

     

Responses of rice to chronic and acute iron toxicity: genotypic differences and biofortification aspects

Background and aims

Iron (Fe) toxicity is a wide-spread stress in lowland rice production. The aim of this study was to differentiate between responses to acute Fe stress during the vegetative stage and chronic Fe stress throughout the growing period.

Methods

Six rice genotypes were tested in a semi-artificial greenhouse setup, in which acute (almost 1500 mg L^?1 Fe in soil solution during the vegetative stage) and chronic (200 to 300 mg L^?1 Fe throughout the season) Fe toxicity were simulated.

Results

Acute Fe stress induced early development of heavy leaf bronzing, whereas moderate symptoms occurred in the chronic treatment throughout the season. Grain yields were only reduced in the chronic stress treatment (?23 %) due to reductions in spikelet fertility, grain number and grain weight. Symptom formation during the early growth stages did not reflect yield responses in all genotypes. Only one genotype showed increases in grain Fe concentrations (24 % in the acute stress and 44 % in the chronic stress) compared to the control.

Conclusions

Contrasting genotypes responded differently to acute and chronic Fe toxicity, and one genotype showed consistent tolerance and the ability to translocate excess Fe into grains. These traits can be useful in the adaptive breeding of rice for Fe toxic environments.

     

Exudate components exert different influences on microbially mediated C losses in simulated rhizosphere soils of a spruce plantation

Aims

An emerging shoot experiences mechanical impedance (MI) prior to initiating photosynthesis, when it needs to break through soil that has a surface crust. This is the one of the first physical stresses that the shoot experiences. Surprisingly, few measurements have been made to understand the impact of this stress upon post-emergent shoot growth.

Methods

A system employed wax layers of different strengths to investigate shoot responses to MI of the soil surface. Experiments tested the responses of plants to MI using wax layers with different strengths, and tested different seed sizes, nitrogen and phosphorus nutrition and different wheat genotypes. Detailed leaf and root morphological responses and photosynthetic gas exchange and fluorescence were measured.

Results

MI produced permanent impairment to limit plant size, leaf growth rate and leaf photosynthetic function. Large seed sizes and N and P fertilization were able to overcome MI, especially for moderate levels of impedance. There was strong genotypic variation in the response to MI among 14 diverse wheat cultivars, and breeding for varieties suitable to no-tillage cropping systems appears to have facilitated selection in the ability to overcome MI of the soil surface.

Conclusions

This study has highlighted the importance of MI stress of the soil surface in limiting shoot growth and has broad implications for plant genotype selection and agricultural systems management, particularly with regard to nutrition and tillage systems.

     

<Emphasis Type="Italic">Trichoderma</Emphasis>-enriched organic fertilizer can mitigate microbiome degeneration of monocropped soil to maintain better plant growth

Background and aims

Given the worldwide effort to improve the nitrogen (N) economy of crops, it is critical to understand the mechanisms of improved N uptake which have resulted from selection pressure for grain yield in Australian wheat (Triticum aestivum L.). Changes in root system traits and N uptake were examined in nine Australian wheat varieties released between 1958 and 2007.

Methods

Wheat varieties were grown in rhizo-boxes in a glasshouse. We measured nitrogen uptake and mapped root growth and proliferation to quantify root length density (RLD), root length per plant, root biomass, specific root length, and plant nitrogen uptake per unit root length.

Results

Selection for yield reduced total RLD and total root length, and increased N uptake per unit root length that overrode the reduction in root system size, effectively explaining the increase in N uptake. Importantly, N uptake in our experiment under controlled conditions matched field measurements, reinforcing the agronomic significance of the present study.

Conclusions

Wheat varieties released in Australia between 1958 and 2007 increased their N uptake, not because of increasing their root length and RLD, but for progressively increasing the efficiency of their root system in capturing N. Our collection of varieties is therefore an interesting model to probe for variation in the affinity of the root system for nitrate.

     

Quantitative analysis of tetrahydrofolate metabolites from <Emphasis Type="Italic">clostridium autoethanogenum</Emphasis>

Introduction

Quantification of tetrahydrofolates (THFs), important metabolites in the Wood–Ljungdahl pathway (WLP) of acetogens, is challenging given their sensitivity to oxygen.

Objective

To develop a simple anaerobic protocol to enable reliable THFs quantification from bioreactors.

Methods

Anaerobic cultures were mixed with anaerobic acetonitrile for extraction. Targeted LC–MS/MS was used for quantification.

Results

Tetrahydrofolates can only be quantified if sampled anaerobically. THF levels showed a strong correlation to acetyl-CoA, the end product of the WLP.

Conclusion

Our method is useful for relative quantification of THFs across different growth conditions. Absolute quantification of THFs requires the use of labelled standards.

     

Soil microalgae modulate grain arsenic accumulation by reducing dimethylarsinic acid and enhancing nutrient uptake in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Background and aims

Microalgae are ubiquitous in paddy soils. However, their roles in arsenic (As) accumulation and transport in rice plants remains unknown.

Methods

Two green algae and five cyanobacteria were used in pot experiments under continuously flooded conditions to ascertain whether a microalgal inoculation could influence rice growth and rice grain As accumulation in plants grown in As-contaminated soils.

Results

The microalgal inoculation greatly enhanced nutrient uptake and rice growth. The presence of representative microalga Anabaena azotica did not significantly differ the grain inorganic As concentrations but remarkably decreased the rice root and grain DMA concentrations. The translocation of As from roots to grains was also markedly decreased by rice inoculated with A. azotica. This subsequently led to a decrease in the total As concentration in rice grains.

Conclusions

The results of the study indicate that the microalgal inoculation had a strong influence on soil pH, soil As speciation, and soil nutrient bioavailability, which significantly affected the rice growth, nutrient uptake, and As accumulation and translocation in rice plants. The results suggest that algae inoculation can be an effective strategy for improving nutrient uptake and reducing As translocation from roots to grains by rice grown in As-contaminated paddy soils.

     

Extraction of natural products from bark of <Emphasis Type="Italic">Betula pendula</Emphasis> using ionic liquids

Introduction

Aqueous–methanol mixtures have successfully been applied to extract a broad range of metabolites from plant tissue. However, a certain amount of material remains insoluble.

Objectives

To enlarge the metabolic compendium, two ionic liquids were selected to extract the methanol insoluble part of trunk from Betula pendula.

Methods

The extracted compounds were analyzed by LC/MS and GC/MS.

Results

The results show that 1-butyl-3-methylimidazolium acetate (IL-Ac) predominantly resulted in fatty acids, whereas 1-ethyl-3-methylimidazolium tosylate (IL-Tos) mostly yielded phenolic structures. Interestingly, bark yielded more ionic liquid soluble metabolites compared to interior wood.

Conclusion

From this one can conclude that the application of ionic liquids may expand the metabolic snapshot.

     

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.

     

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.

     

Cadmium reduces zinc uptake but enhances its translocation in the cadmium-accumulator, <Emphasis Type="Italic">Carpobrotus rossii</Emphasis>, without affecting speciation

Background and aims

Interactions between Cd and Zn occur in soils and plants but are inconsistent. This study examined how Cd/Zn interactions influence the growth of Carpobrotus rossii (Haw.) and the accumulation of Cd and Zn in plants.

Methods

Plants were grown in nutrient solutions containing 5–100 μM Zn and 0, 5 or 15 μM Cd. Plant growth and tissue concentrations were measured, and the speciation of Zn within the plant tissues determined using synchrotron-based X-ray absorption spectroscopy.

Results

There was an additive negative interaction between Cd and Zn on root growth. Only the highest level of Zn (100 μM) decreased Cd concentrations in root and shoot tissues (by 40–64%), whilst 100 μM Zn enhanced Cd translocation at 5 μM Cd but decreased it at 15 μM Cd. In contrast, both 5 and 15 μM Cd decreased Zn concentrations in root and shoot tissues but increased Zn translocation by 30–90%. This interaction was not associated with changes in Zn speciation within the plants, with most Zn associated with oxalate (48–87%).

Conclusions

The presence of Zn and Cd resulted in an additive negative effect on root growth, but an antagonistic pattern in their accumulation in shoots of C. rossii.

     

Metabolic response of porcine colon explants to in vitro infection by <Emphasis Type="Italic">Brachyspira hyodysenteriae</Emphasis>: a leap into disease pathophysiology

Introduction

Swine dysentery caused by Brachyspira hyodysenteriae is a production limiting disease in pig farming. Currently antimicrobial therapy is the only treatment and control method available.

Objective

The aim of this study was to characterize the metabolic response of porcine colon explants to infection by B. hyodysenteriae.

Methods

Porcine colon explants exposed to B. hyodysenteriae were analyzed for histopathological, metabolic and pro-inflammatory gene expression changes.

Results

Significant epithelial necrosis, increased levels of l-citrulline and IL-1α were observed on explants infected with B. hyodysenteriae.

Conclusions

The spirochete induces necrosis in vitro likely through an inflammatory process mediated by IL-1α and NO.

     

<Emphasis Type="Italic">massPix</Emphasis>: an R package for annotation and interpretation of mass spectrometry imaging data for lipidomics

Introduction

Mass spectrometry imaging (MSI) experiments result in complex multi-dimensional datasets, which require specialist data analysis tools.

Objectives

We have developed massPix—an R package for analysing and interpreting data from MSI of lipids in tissue.

Methods

massPix produces single ion images, performs multivariate statistics and provides putative lipid annotations based on accurate mass matching against generated lipid libraries.

Results

Classification of tissue regions with high spectral similarly can be carried out by principal components analysis (PCA) or k-means clustering.

Conclusion

massPix is an open-source tool for the analysis and statistical interpretation of MSI data, and is particularly useful for lipidomics applications.

     

Zinc uptake by roots and accumulation in maize plants as affected by phosphorus application and arbuscular mycorrhizal colonization

Background and aims

Phosphorus (P) application reduces the zinc (Zn) concentration of cereal grain, but the mechanisms, including root Zn accumulation, remain controversial.

Methods

Field and pot experiments were conducted to determine the degree to which root Zn accumulation, root arbuscular mycorrhizal (AM) colonization, and other factors contribute to the negative interaction between P and Zn.

Results

Root Zn accumulation was positively related to shoot Zn accumulation. In responding to P application, root Zn accumulation was more affected by changes in AM colonization than by changes in root dry weight (RDW). In the pot experiment without Zn supply, root Zn concentration (RZnC), RDW, and AM colonization together explained 98% (adjusted R² value) of the decrease in root Zn accumulation with P application, while AM colonization and RDW explained 66% (adjusted R² value) of decrease in total Zn accumulation. In the pot experiment with Zn sufficient supply, RZnC and RDW explained 89% (adjusted R² value) of the decrease in root Zn accumulation with increasing P application, while RDW, RZnC, and AM colonization explained 53% (adjusted R² value) of the decrease in total Zn accumulation.

Conclusion

Especially in Zn-deficient soil, root Zn accumulation explains much of the negative interaction between P and Zn, and root Zn accumulation is greatly affected by AM colonization.

     

Arbuscular mycorrhizal fungi can shift plant-soil feedback of grass-endophyte symbiosis from negative to positive

Background and aims

Variations in root-associated fungal communities contribute to the so-called ‘crop rotation benefit’ on soil productivity. We assessed the effects of chickpea, lentil, and pea in wheat-based rotations, as compared to wheat monoculture, on the structure of root-associated fungal communities, and described the legacy of pulses on a following wheat crop.

Methods

The internal transcribed spacer (ITS) and 18S rRNA gene markers, and 454 amplicon pyrosequencing were used to describe the fungal communities of crop roots and rhizosphere soil in a field experiment and agronomic data were collected.

Results

Pulses influenced only the structure of the non-mycorrhizal fungal community of roots. Fusarium tricinctum, Clonostachys rosea, Fusarium redolens, and Cryptococcus sp. were specific to certain crops. Despite the absence of selective effects of pulses on their associated arbuscular mycorrhizal (AM) fungal community, pea had a legacy effect on the structure of the AM fungal community associated with the roots of the following wheat crop, in one of the two year/sites examined. Species of Mortierella, Cryptococcus, and Paraglomus in wheat rhizosphere soil may benefit yield, whereas species of Fusarium, Davidiella, Lachnum, Sistotrema and Podospora may reduce yield.

Conclusion

The effect of pulse crops on root fungal communities varied with rotation crop species. Pulses had various effects on the physiology of the following wheat crop, including increased productivity.

     

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.

     

Interspecific and intergeneric hybridization as a source of variation for wheat grain quality improvement

Key message

The hybridization events with wild relatives and old varieties are an alternative source for enlarging the wheat quality variability. This review describes these process and their effects on the technological and nutritional quality.

Abstract

Wheat quality and its end-uses are mainly based on variation in three traits: grain hardness, gluten quality and starch. In recent times, the importance of nutritional quality and health-related aspects has increased the range of these traits with the inclusion of other grain components such as vitamins, fibre and micronutrients. One option to enlarge the genetic variability in wheat for all these components has been the use of wild relatives, together with underutilised or neglected wheat varieties or species. In the current review, we summarise the role of each grain component in relation to grain quality, their variation in modern wheat and the alternative sources in which wheat breeders have found novel variation.

     

Screening for internal phosphorus utilisation efficiency: comparison of genotypes at equal shoot P content is critical

Aims

Progress in improving the internal phosphorus utilisation efficiency of crops has been limited, which may be due to poor screening methods that allow differences in P uptake among genotypes grown in soil to mask genotypic differences in shoot biomass produced per unit of shoot P (PUE). We investigated alternative soil and hydroponic screening methods for their capacity to produce a consensus ranking of genotypes with regard to PUE.

Methods

Six rice genotypes previously identified in hydroponic screening studies as being high, intermediate or low in PUE were screened using multi P rate hydroponic and soil-based experiments.

Results

Comparisons made at each rate of soil-P supply produced estimates of PUE strongly biased by P uptake differences among genotypes. Using multiple-rate data to derive response functions per genotype showed that similar P content was achieved at different rates of P supply but that high-PUE genotypes clearly separated from intermediate- and low-PUE genotypes if equal P content was used. Ranking analysis suggested that results obtained from soil agreed well with those from the hydroponic study.

Conclusions

PUE was significantly influenced by genotype and P supply, but there was no significant genotype x P supply interaction. Hence, we conclude that screening genotypes using hydroponics at one or two P supply levels is the most cost- and time effective means to screen large numbers of rice genotypes for PUE.

     

High abundance of non-mycorrhizal plant species in severely phosphorus-impoverished Brazilian <Emphasis Type="Italic">campos rupestres</Emphasis>

Background and aims

We sought to describe the species and functional composition of Brazilian campos rupestres plant communities on severely nutrient-impoverished white sands, to test hypotheses relating plant communities and physiological adaptations to infertile soils. Based on recently-published information on a south-western Australian dune chronosequence, we hypothesised that campos rupestres plant communities would similarly contain a relatively large proportion of non-mycorrhizal species, because of the phosphorus-(P) impoverished nature of the soils. We also sought to test the hypothesis that many of these non-mycorrhizal species have high leaf manganese (Mn) concentrations as a consequence of carboxylate exudation to mobilise soil P.

Methods

We conducted flora surveys and quantified mycorrhizal status and foliar Mn concentrations in field sites with strongly-weathered sandy soils. Rhizosphere carboxylates were collected from glasshouse-grown plants to assess a potential correlation of carboxylates and leaf Mn concentrations.

Results

Soils were depleted of all major plant nutrients. Non-mycorrhizal plants were abundant in most field sites (mean relative cover = 48%). Vellozia species were dominant aboveground; belowground, roots were colonised more by dark septate endophytic fungi than by mycorrhizal fungi. From the field sites, foliar Mn concentrations in non-mycorrhizal species increased with decreasing soil P concentrations, but only when soil Mn concentrations were above a minimum threshold (exchangeable [Mn] above detection limit). Across all species, however, there was no relationship of foliar Mn concentrations with soil P concentrations.

Conclusions

Our hypothesis that white-sand campos rupestres communities contain a relatively large proportion of non-mycorrhizal plants was supported. Comparison with similar ecosystems in south-western Australia suggests that plant communities on severely P-impoverished sandy soils, despite differing evolutionary histories and little overlap in plant families, follow convergent evolutionary paths towards increasing abundance of non-mycorrhizal species.

     

Characterization of ankylosing spondylitis and rheumatoid arthritis using <Superscript>1</Superscript>H NMR-based metabolomics of human fecal extracts

Introduction

The differences in fecal metabolome between ankylosing spondylitis (AS)/rheumatoid arthritis (RA) patients and healthy individuals could be the reason for an autoimmune disorder.

Objectives

The study explored the fecal metabolome difference between AS/RA patients and healthy controls to clarify human immune disturbance.

Methods

Fecal samples from 109 individuals (healthy controls 34, AS 40, and RA 35) were analyzed by ¹H NMR spectroscopy. Data were analyzed with principal component analysis (PCA) and orthogonal projection to latent structure discriminant (OPLS-DA) analysis.

Results

Significant differences in the fecal metabolic profiles could distinguish AS/RA patients from healthy controls but could not distinguish between AS and RA patients. The significantly decreased metabolites in AS/RA patients were butyrate, propionate, methionine, and hypoxanthine. Significantly increased metabolites in AS/RA patients were taurine, methanol, fumarate, and tryptophan.

Conclusion

The metabolome variations in feces indicated AS and RA were two homologous diseases that could not be distinguished by ¹H NMR metabolomics.