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Ginseng, from the roots of Panax ginseng C. A. Meyer, is a widely used herbal medicine in Asian countries, known for its excellent therapeutic properties. The growth of P. ginseng is depend on specific and strict environments, with a preference for wetness but intolerance for flooding. Under excessive soil moisture, some irregular rust-like substances are deposited on the root epidermis, causing ginseng rusty symptoms (GRS). This condition leads to a significant reduce in yield and quality, resulting in substantial economic loses. However, there is less knowledge on the cause of GRS and there are no effective treatments available for its treatment once it occurs. Unsuitable environments lead to the generation of large amounts of reactive oxygen species (ROS). We investigated the key indicators associated with the stress response during different physiological stages of GRS development. We observed a significant change in ROS level, MDA contents, antioxidant enzymes activities, and non-enzymatic antioxidants contents prior to the GRS. Through the analysis of soil features with an abundance of moisture, we further determined the source of ROS. The levels of nitrate reductase (NR) and nitric oxide synthase (NOS) activities in the inter-root soil of ginseng with GRS were significantly elevated compared to those of healthy ginseng. These enzymes boost nitric oxide (NO) levels, which in turn showed a favorable correlation with the GRS. The activities of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase first rose and then decreased as GRS developed. Excess soil moisture causes a decrease in oxygen levels. This activated NR and NOS in the soil, resulting in a production of excess NO. The NO then diffused into the ginseng root and triggered a burst of ROS through NADPH located on the cell membrane. Additionally, Fe2+ in soil was oxidized to red Fe3+, and finally led to GRS. This conclusion was also verified by the Sodium Nitroprusside (SNP), a precursor compound producing NO. The presence of NO from NR and NOS in water-saturated soil is responsible for the generation of ROS. Among these, NO is the main component that contribute to the occurrence of GRS. [ABSTRACT FROM AUTHOR]

To analyse the effect of nutrient management on the growth, physiology, energy utilization, production and quality of black gram, a field trial on black gram was conducted at eastern Indian Gangetic alluvium during the autumn of 2020 and 2021. Treatments were two soil applications of cobalt (Co) and foliar spray of potassium (K) and boron (B) in five combinations. All treatments were arranged in a split-plot design and repeated three times. Two soil applications of cobalt (Co) were assigned in the main plots and foliar spray of potassium (K) and boron (B) in five combinations were assigned in sub-plots. Applications of Co in soil and foliar K+B facilitated significantly higher (p≤0.05) values for aerial dry matter (ADM), leaf area index (LAI), nodules per plant, total chlorophyll, net photosynthetic rate and nitrate reductase content in both 2020 and 2021, with a greater realization of photosynthetically active radiation interception, and use efficiency (IPAR and PARUE respectively), seed yield, seed nutrients and protein contents. Differences in LAI exhibited positive and linear correlation with IPAR explaining more than 60% variations in different growth stages. The innovative combination of soil Co (beneficial nutrient) application at 4 kg ha−1 combined with foliar 1.25% K (macronutrient) + 0.2% B (micronutrient) spray is a potential agronomic management schedule for the farmers to sustain optimum production of autumn black gram through substantial upgradation of growth, physiology, energy utilization, production and quality in Indian subtropics. [ABSTRACT FROM AUTHOR]

Drought is a prominent abiotic stress that is exacerbated by climate change. The application of plant growth regulators (PGRs) and plant growth-promoting rhizobacteria (PGPR) has been considered an effective approach to mitigate adverse effects of drought stress. This study aimed to evaluate the effect of paclobutrazol (PBZ) and three rhizobacterial strains on various physiological parameters of wheat under drought stress. Experimental treatments consisted of three irrigation levels as the first main plot, and PBZ application at three levels as the second main plot. Furthermore, PGPR was applied at five levels as subplot. Results revealed that drought stress decreased relative water content (34%), chlorophyll fluorescence parameters, water use efficiency (WUE) (49%), Rubisco activity (40%), and increased antioxidant enzymes and malondialdehyde (52%), whereas PBZ treatment increased relative water content (RWC) (44%), and grain yield (WUEgy) (14%) compared to control treatment. Furthermore, the PGPR combination improved florescence parameters (by an average of 27%), catalase (34%), superoxide dismutase (22%), and nitrate reductase (34%) compared with control treatment. Moreover, grain yield correlated positively and significantly with chlorophyll content, and Rubisco and nitrate reductase activity, while it negatively correlated with malondialdehyde. In light of these findings, it is evident that a combination of PBZ and PGPR treatments emerges as a highly recommended approach for mitigating the adverse effects of water deficits, especially in the context of escalating climate change challenges. [ABSTRACT FROM AUTHOR]

AbstractInoculation with Pseudomonas fluorescens has been widely used due to its growth promotion and potential influence on plant nitrogen (N) metabolism. The objective of this study was to estimate the rate of P. fluorescens that provides the greatest growth, chlorophyll, foliar nitrate reductase (NR) enzyme activity and the reduction of nitrate (NO3−) accumulation in hydroponic lettuce plants. The treatments consisted of different rates of P. fluorescens inoculant via the nutrient solution, with rates ranging from 0, 8, 16, 32 and 64 mL 100 L−1 of solution. Inoculating with P. fluorescens at a dosage ranging from 23 and 34 mL 100 L−1 of solution resulted in significantly greater fresh and dry mass for both the shoots and roots of the plants. Notably, at rates of 32 and 37 mL 100 L−1 of P. fluorescens, there was a 39% increase in N accumulation and a remarkable 192% increase in ammonium (NH4+) accumulation in the shoots. Simultaneously, there was a significant 65% reduction in NO3− accumulation in the shoots, and at the highest rate of P. fluorescens, the NR activity increased. In addition, it was observed an increasing in the concentration of chlorophyll a, chlorophyll b, carotenoids, total carbohydrates and total amino acids in the leaves by 43, 74, 50, 98 and 165% at rates of 35, 36, 37, 38 and 50 mL 100 L−1 of P. fluorescens. Inoculation of P. fluorescens at a rate of 35 mL 100 L−1 via nutrient solution in hydroponic lettuce cultivation provided increase of photosynthetic efficiency, N uptake, mass accumulation, shoot yield and a decrease in the accumulation of NO3− in the plant shoots. [ABSTRACT FROM AUTHOR]

Corynebacterium pseudotuberculosis (CPS) is an important bacterial animal pathogen. CPS causes chronic, debilitating and currently incurable infectious diseases affecting a wide range of livestock and wild herbivores including camelids worldwide. Belonging to the Corynebacterium diphtheriae complex, this pathogen can also infect humans. The classical characterization of CPS is typically based on the testing of nitrate reductase activity, separating the two biovars Equi and Ovis. However, more refined resolutions are required to unravel routes of infection. This was realized in our study by generating and analyzing whole genome sequencing (WGS) data. Using newly created core genome multilocus sequence typing (cgMLST) profiles we were the first to discover isolates grouping in a cluster adjacent to clusters formed by CPS biovar Equi isolates. This novel cluster includes CPS isolates from alpacas, llamas, camels and dromedaries, which are characterized by a lack of nitrate reductase activity as encountered in biovar Ovis. This is of special interest for molecular epidemiology. Nevertheless, these isolates bear the genes of the nitrate locus, which are characteristic of biovar Equi isolates. However, sequence analysis of the genes narG and narH of the nitrate locus revealed indels leading to frameshifts and inactivity of the enzymes involved in nitrate reduction. Interestingly, one CPS isolate originating from another lama with an insertion in the MFS transporter (narT) is adjacent to a cluster formed by ovine CPS isolates biovar Equi. Based on this knowledge, the combination of biochemical and PCR based molecular biological nitrate reductase detection can be used for a fast and uncomplicated classification of isolates in routine diagnostics in order to check the origin of camelid CPS isolates. Further analysis revealed that partial sequencing of the ABC transporter substrate binding protein (CP258_RS07935) is a powerful tool to assign the biovars and the novel genomovar. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the effect of dexamethasone (DXM) on acute lung and kidney injury with sepsis and its possible mechanism. Methods: Control (NC), lipopolysaccharide (LPS) and lipopolysaccharide + dexamethasone (LPS+DXM) treated groups were established by random assignment of 72 Wistar rats. The NC rats were injected with physiological saline, while the LPS group was injected with LPS (5 mg/kg) and LPS+DXM group was injected with LPS(5 mg/kg) first and followed by DXM (1 mg/kg). Serum tumor necrosis factor-α (TNF-α) and serum macrophage inflammatory protein 1α (MIP-1α) were measured by ELISA. Lung wet/dry weight ratio, serum creatinine(SCR) and blood urea nitrogen(BUN) were determined at various time points. Hematoxylin Eosin staining (HE) for pathological changes in the lung and kidney. Radioimmunoassay was used to detect the levels of angiotensin II (Ang II) in plasma, lung and kidney tissues. Immunohistochemistry and western blot (WB) were used to detect angiotensin II receptor type 1 (AT1R) protein and angiotensin II receptor type 2 (AT2R) protein in lung and kidney tissues. The level of nitric oxide (NO) in serum, lung and kidney were detected using nitrate reductase method. Results: Compared with control group, serum TNF-α, MIP-1α, SCR, BUN, lung W/D, Ang II level in plasma, lung and kidney, lung and kidney AT2R protein, NO level in serum, lung and kidney were significantly elevated(P<0.05) and pathological damage of lung and kidney tissues were showed in LPS group rats (P<0.05), whereas DXM down-regulated the above indexes and alleviate pathological damage of lung and kidney tissues. However, the expression of the lung and kidney AT1R protein was opposite to the above results. Conclusions: Sepsis can cause acute lung and kidney injury and changes RAAS components in circulating, lung and renal. DXM can improve acute lung and kidney injury in septic rats, and the mechanism may be related to the down-regulation of inflammatory factors, AngII, AT2R, NO and up-regulation of AT1R expression by DXM. [ABSTRACT FROM AUTHOR]

Denitrification is a crucial process in the global nitrogen cycle, in which two functionally equivalent genes, nirS and nirK, catalyse the critical reaction and are usually used as marker genes. The nirK gene can function independently, whereas nirS requires additional genes to encode nitrite reductase and is more sensitive to environmental factors than nirK. However, the ecological differentiation mechanisms of those denitrifying microbial communities and their adaptation strategies to environmental stresses remain unclear. Here, we conducted metagenomic analysis for sediments and bioreactor samples from Lake Donghu, China. We found that nirS‐type denitrifying communities had a significantly lower horizontal gene transfer frequency than that of nirK‐type denitrifying communities, and nirS gene phylogeny was more congruent with taxonomy than that of nirK gene. Metabolic reconstruction of metagenome‐assembled genomes further revealed that nirS‐type denitrifying communities have robust metabolic systems for energy conservation, enabling them to survive under environmental stresses. Nevertheless, nirK‐type denitrifying communities seemed to adapt to oxygen‐limited environments with the ability to utilize various carbon and nitrogen compounds. Thus, this study provides novel insights into the ecological differentiation mechanism of nirS and nirK‐type denitrifying communities, as well as the regulation of the global nitrogen cycle and greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

The issue of heavy metal pollution such as nickel poses a significant environmental concern, exerting detrimental effects on the growth and viability of plant life. Plants have various mechanisms to effectively manage heavy metal stress, including the ability to modify their amino acid type and content. This adaptive response allows plants to mitigate the detrimental effects caused by excessive heavy metal accumulation. The aim of this study was to investigate the effect of biofertilizers on nickel accumulation, nitrogen metabolism and amino acid profile of corn (Zea mays L.) cv. 'PL438' exposed to Ni stress. After disinfecting and soaking in water for 24 h, corn seeds were primed with bacterial biofertilizers (T2: NPK + FZ), fungal biofertilizers (T3: Arbuscular mycorrhizal fungi (AMF) + Trichoderma (T)), or a combination of them (T4: NPK + FZ + AMF + T) and were cultured by the hydroponic method in completely controlled conditions. Then, they were simultaneously exposed to nickel chloride at various rates (0, 75, or 150 µM) at the three-leaf stage. They were harvested two weeks later and were subjected to the measurement of Ni content, nitrate and nitrite content, nitrate reductase activity, and amino acid profile by high-performance liquid chromatography. The results showed that the application of Ni at higher rates increased Ni, nitrate, and nitrite contents and nitrate reductase activity. The study of Ni accumulation and TF revealed that Ni accumulated in the roots to a greater extent than in the shoots and TF was < 1 in all treatments. The shoot amino acid profile showed that the treatment of Ni+2 increased som amino acids such as aspartic acid, asparagine, serine, histidine, and glycine versus the control, whereas T4 Ni+2 increased aspartic acid, glutamic acid, threonine and arginine. The change in amino acids in Ni-treated plants may play a key role in their adaptation to Ni stress. The findings indicate that biofertilizers played a crucial role in mitigating the negative impacts of Ni on corn plants through alterations in amino acid composition and decreased absorption and translocation of Ni. [ABSTRACT FROM AUTHOR]

Achieving the green development of agriculture requires the reduction of chemical nitrogen (N) fertilizer input. Previous studies have confirmed that returning green manure to the field is an effective measure to improve crop yields while substituting partial chemical N fertilizer. However, it remains unclear how to further intensify the substituting function of green manure and elucidate its underlying agronomic mechanism. In a split-plot field experiment in spring wheat, different green manures returned to the field under reduced chemical N supply was established in an oasis area since 2018, in order to investigate the effect of green manure and reduced N on grain yield, N uptake, N use efficiency (NUE), N nutrition index, soil organic matter, and soil N of wheat in 2020-2022. Our results showed that mixed sown common vetch and hairy vetch can substitute 40% of chemical N fertilizer without reducing grain yield or N accumulation. Noteworthily, mixed sown common vetch and hairy vetch under reduced N by 20% showed the highest N agronomy efficiency and recovery efficiency, which were 92.0% and 46.0% higher than fallow after wheat harvest and conventional N application rate, respectively. The increase in NUE of wheat was mainly attributed to mixed sown common vetch and hairy vetch, which increased N transportation quantity and transportation rate at pre-anthesis, enhanced N harvest index, optimized N nutrition index, and increased activities of nitrate reductase and glutamine synthetase of leaf, respectively. Meanwhile, mixed sown common vetch and hairy vetch under reduced N by 20% improved soil organic matter and N contents. Therefore, mixed sown common vetch and hairy vetch can substitute 40% of chemical N fertilizer while maintaining grain yield and N accumulation, and it combined with reduced chemical N by 20% or 40% improved NUE of wheat via enhancing N supply and uptake. [ABSTRACT FROM AUTHOR]

Aims: Enhancing crop yields is a contemporary challenge of the modern world, and selenium (Se) has been shown to improve plant health against various abiotic stressors. This study aimed to evaluate the influence of Se on the biosynthesis of photosynthetic pigments, nitrogen metabolism, antioxidant metabolism, flavonoid synthesis and nodulation of cowpea plants. Methods: We carried out a soil experiment with five Se application rates (0, 7.5, 15, 30, and 45 µg kg−1) and a hydroponics experiment with four Se concentrations (0, 5, 10, and 15 µmol L−1). Results: Both experiments revealed hormetic-like responses of cowpea plants to Se, at both molecular and whole-plant levels. Se dose-dependently increased the synthesis of chlorophylls, carotenoids and pheophytin as well as the efficiency of enzymatic antioxidant metabolism by decreasing MDA levels and increasing CAT and APX activity. Selenium also enhanced nitrate reductase activity, resulting in greater biosynthesis of amino acids and proteins in the leaves. However, the dose responses were not identical in the two experiments. Hormetic-like biphasic responses were uniquely revealed for daidzein, genistein, and kaempferol in the hydroponics experiment. Selenium also enhanced the number of nodules in roots, which generated increases in the production of ureides and greater production of shoot dry weight in both experiments. Low rates of Se stimulated the translocation of allantoic acid from nodules to leaves. Conclusions: This study adds new insights regarding Se effect on antioxidant and nitrogen metabolism, photosynthetic pigments and nodulation, which can increase cowpea yield. [ABSTRACT FROM AUTHOR]

Boron (B) deficiency has been shown to inhibit root cell growth and division. However, the precise mechanism underlying B deficiency-mediated root tip growth inhibition remains unclear. In this study, we investigated the role of BnaA3.NIP5;1, a gene encoding a boric acid channel, in Brassica napus (B. napus). BnaA3.NIP5;1 is expressed in the lateral root cap and contributes to B acquisition in the root tip. Downregulation of BnaA3.NIP5;1 enhances B sensitivity in B. napus, resulting in reduced shoot biomass and impaired root tip development. Transcriptome analysis was conducted on root tips from wild-type B. napus (QY10) and BnaA3.NIP5;1 RNAi lines to assess the significance of B dynamics in meristematic cells during seedling growth. Differentially expressed genes (DEGs) were significantly enriched in plant circadian rhythm and nitrogen (N) metabolism pathways. Notably, the circadian-rhythm-related gene HY5 exhibited a similar B regulation pattern in Arabidopsis to that observed in B. napus. Furthermore, Arabidopsis mutants with disrupted circadian rhythm (hy5/cor27/toc1) displayed heightened sensitivity to low B compared to the wild type (Col-0). Consistent with expectations, B deficiency significantly disrupted N metabolism in B. napus roots, affecting nitrogen concentration, nitrate reductase enzyme activity, and glutamine synthesis. Interestingly, this disruption was exacerbated in BnaA3NIP5;1 RNAi lines. Overall, our findings highlight the critical role of B dynamics in root tip cells, impacting circadian rhythm and N metabolism, ultimately leading to retarded growth. This study provides novel insights into B regulation in root tip development and overall root growth in B. napus. [ABSTRACT FROM AUTHOR]

Drought stress can impair plant growth and development. Nitric oxide (NO), a gas signaling molecule, delays injuries caused by abiotic stress. This study explored the roles of NO during adventitious rooting in cucumber (Cucumis sativus L.) under drought stress. Our results found that 0.05% (W/V) polyethylene glycol 6000 (PEG) treatment significantly suppressed adventitious root formation, but 10 μM GSNO (a NO donor) treatment could significantly reverse the negative effect of drought stress. Under drought stress, MDA, H2O2 and O2·− accumulation were increased during rooting. Nevertheless, the application of exogenous NO decreased reactive oxygen (ROS) accumulation, revealing that NO might play an essential role in improving drought tolerance. Compared with PEG treatment, PEG + GSNO treatment enhanced the level of glutathione (GSH), ascorbic acid (AsA), and GSH/GSSG ratio, while decreasing glutathione disulfde (GSSG) content. In comparison with PEG treatment, PEG + GSNO treatment significantly increased the activity of antioxidant enzymes (APX, AAO, GR, and MDHAR) and the expression level of related enzyme genes (CsAPX, CsAAO, CsGR, and CsMDHAR). In addition, PEG + GSNO treatment also increased endogenous NO and S-nitrosothiol (SNO) content, nitrate reductase (NR) activity, and total S-nitrosylated proteins, and the expression of CsNR, while PEG + GSNO treatment decreased S-nitrosoglutathione reductase (GSNOR) activity, suggesting that protein S-nitrosylation might be involved in adventitious rooting under drought stress. In summary, our results indicate that NO could promote adventitious root formation under drought stress via regulating ascorbate glutathione (AsA-GSH) pathway cycle and protein posttranslational S-nitrosylation. [ABSTRACT FROM AUTHOR]

Downy mildew is one of the main diseases that cause a reduction in cucumber yield. Chemical control not only increases pathogenic bacteria resistance and causes environmental pollution but also endangers the health of humans as they are abundant pesticide residues in fruits. Dopamine, a strong antioxidant that widely exists in plants, can effectively protect plants from the adverse effects of such chemicals. In this study, the susceptible cucumber cultivar 'Changchun Mici' and the disease-resistant cultivar 'Jinchun No. 4' were used as test materials to explore the alleviating effect of exogenous dopamine on cucumber downy mildew. After downy mildew infection, exogenous dopamine (100 µmol L−1) had the greatest significant effect on improving the disease resistance of cucumber, increasing the activities of superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase in cucumber, thereby reducing the accumulation of the superoxide anion and hydrogen peroxide in leaves, the content of malondialdehyde, and the relative electrical conductivity in leaves, which significantly improved the antioxidant capacity of cucumber. Simultaneously, exogenous dopamine increased the leaf wax content and trichome density; the activities of polyphenol oxidase, chitinase, and β-1,3-glucanase; and the expression of CsPR1, so that the disease index was significantly reduced. As for nitrogen metabolism, exogenous dopamine significantly increased the activities of nitrate reductase, glutamine synthase, glutamate synthase, and glutamate dehydrogenase, as well as the content of nitrate nitrogen, whereas it decreased the accumulation of ammonium nitrogen, thereby promoting nitrogen metabolism in cucumber. As a consequence, exogenous dopamine improved the yield and quality of cucumbers infected by downy mildew. [ABSTRACT FROM AUTHOR]

Partial denitrification granular sludge (PDGS) can provide long-term stable nitrite for anaerobic ammonia oxidation (anammox). The cultivation of ordinary activated sludge from wastewater treatment plants into PDGS can further promote the application of PD in practical engineering. In this study, the feasibility of fast start-up of PDGS was explored by inoculating waste sludge in up-flow anaerobic sludge blanket (UASB) reactor with synergistic control of nitrogen load rate (NLR, 0.05–0.65 kg N/m3/d) and electron donor starvation (EDS) (240–168 mg L−1), and system performance, particle characteristics and microbial structure were studied. The results showed that PD-UASB started successfully within 48 days, the average nitrite accumulation rate (NTR) and nitrate removal ratio (NRR) reached 79.6% and 82.5% after successful initiation, accompanied by high abundance of PD bacteria (Thauera, Pseudomonas, unclassflied commamonadaceae and Limnobacter) (25.3%). The increase of PD activity, and the difference between nitrate reductase (NAR) and nitrite reductase (NIR) contributed to nitrite production. Besides, the sludge shifted from flocculated (≤0.5 mm, 95.37%) to granulated state (0.5–2 mm, 64.74%), which could be due to the increase of extracellular polymers (EPS) (especially T-EPS) and metabolism of specific microorganisms (Bacteroidota and Chloroflexi, 19.92%). Good sludge granulation promoted the settleability of PD (the SVI5 was 47.248 mL/ g. ss after successful start-up). In summary, good PD sludge granulation process could be achieved in a short time by synergistically controlling NLR and EDS. [ABSTRACT FROM AUTHOR]

Our study aimed to assess the impact of sprinkler irrigation on the activity of selected soil enzymes in terms of nitrogen metabolism and oxidation–reduction processes in soil with different doses of inorganic nitrogen fertilizers. An Alfisol was sampled from an experimental field of spring barley within the University Research Center in the central part of Poland, namely the village of Mochełek with a moderate transitory climate, during the growing seasons of 2015–2017. The soil resistance (RS) was derived to recognize the resistance enzymes during drought. In the maturity phase, nitrate reductase activity was 18% higher in irrigated soil and the activities of other enzymes were higher than in the non-irrigated plots by 25% for dehydrogenase, 22% for peroxidase, 33% for catalase, and 17% for urease. The development phase in the barley influenced nitrate reductase activity. Enzymatic activities changed throughout the research years. During the maturity stage, a lower ammonium nitrogen content in the soil resulted from a higher spring barley uptake due to drought stress. Irrigation probably contributed to increased leaching of nitrate in the soil. The highest index of resilience was found in the soil catalase activity. [ABSTRACT FROM AUTHOR]

Protein hydrolysates are plant biostimulants containing amino acids, oligopeptides, and peptides in their composition. When supplied to plants, protein hydrolysates (HPs) have been identified to improve nitrogen metabolism, enhance the activity of antioxidant enzymes, boost plant defense response to stresses, and positively impact the quantity and quality of products. Soybean is a crucial global commodity, with nitrogen being the primary nutrient for crop development as it directly affects productivity. This study aimed to evaluate the effect of an HP-based biostimulant on the N metabolism in nodulated soybean plants and their productivity. A greenhouse experiment was conducted to test two modes of application of the 0.20% HP-based biostimulant. Soybean plants, growing in pots, were treated with 0.20% HP either via seed treatment or foliar application (at growth stages V3 and V5). Activities of enzymes and compounds related to N metabolism, gene expression, and productivity components were analyzed. It was observed that the mode of application did not significantly influence the results. The application of HPs increased the concentration of nitrate, amino acids, and ureides in soybean leaves. It also positively altered the expression of genes such as nitrate reductase, urease, and asparagine. Additionally, it enhanced productivity, resulting in plants with a greater number and weight of pods and grains. Therefore, it is possible to consider HPs as a stimulator for increasing soybean productivity, even under non-stressing conditions. [ABSTRACT FROM AUTHOR]

Background and Objectives: Oxidative stress resulting from a disturbance of the endogenous redox system is suspected in numerous diseases of the central nervous system, including epilepsy. In addition, antiseizure medications (ASMs), especially those of the old generation, may further increase oxidative stress. To evaluate the effects of ASM generation on oxidative stress, we conducted a cross-sectional study in patients with epilepsy treated with old, new, and polytherapy. Materials and Methods: The antioxidant activity of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase, as well as the concentrations of malondialdehyde, protein carbonyl, nitrate, nitrite, and glutathione in reduced and oxidized forms, were measured in 49 patients with epilepsy and 14 healthy controls. In addition, the plasma concentrations of ASMs and metabolites of carbamazepine and valproic acid were measured in the patients. Results: Patients with epilepsy showed increased activities of superoxide dismutase and catalase (p < 0.001), concentrations of glutathione disulfide and markers of nitric oxide metabolism (p < 0.001), and decreased activities of glutathione peroxidase, glutathione reductase, glutathione, and nitrite concentrations (p ≤ 0.005) compared to healthy controls. A comparison of ASM generations revealed increased levels of superoxide dismutase and catalase (p ≤ 0.007) and decreased levels of glutathione peroxidase and glutathione reductase (p ≤ 0.01) in patients treated with old ASMs compared to those treated with new generation ASMs. In addition, an increase in protein carbonyl and nitric oxide metabolites (p ≤ 0.002) was observed in patients treated with old generation ASMs compared to those treated with new generation ASMs. Most oxidative stress parameters in patients receiving polytherapy with ASMs were intermediate between the results of patients treated with the old and new generations of ASMs. Conclusions: An increase in oxidative stress markers and modulation of antioxidant enzyme activities was observed in patients with epilepsy compared to controls. The results of our study showed significantly higher oxidative stress in patients treated with old ASMs compared to those treated with new generation ASMs. [ABSTRACT FROM AUTHOR]

AbstractSerotonin is a well-known animal hormone and ubiquitous monoamine. In recent years, its presence in plants has attracted the attention of many researchers. In plants, serotonin as signaling hormone plays a pivotal role in hormonal crosstalk, regulating antioxidant metabolism and developmental processes under abiotic stresses. Among abiotic stresses, salt stress considerably influences Guizotia abyssinica growth and physio-chemical functions. The effect of exogenous serotonin was assessed to ameliorate the harmful effect of salinity stress at different levels. All the growth parameters, chlorophyll pigments, gas exchange indicators, and nitrate reductase activity were decreased under all salinity levels while 2-thiobarbituric acid reactive substances (TBARS), proline, and antioxidant activities were increased. Serotonin improved the length of roots and shoots, basal diameter, leaf number, area, width and length, root dry matter, stem dry matter, leaves dry matter, chlorophyll a, chlorophyll b, chlorophyll fluorescence, transpiration rate, stomatal conductance, photosynthetic rate, relative water content, water use efficiency, and nitrate reductase under salt stress condition. Moreover, the upregulation of antioxidant enzymes evoked by the salt stress was further enhanced. Taken together, salt stress inhibited the growth and performance of G. abyssinica, however, exogenous application of serotonin fortified its tolerance by mitigating membrane damage and improving assimilatory functions, plant water status and plant defense metabolism, thereby lowering the adverse effects of salt stress on various plant growth performance and physio-biochemical functions. [ABSTRACT FROM AUTHOR]

Drawing inspiration from the nitrate reductase enzymes, which catalyze nitrate to nitrite in nature, here a bio‐inspired, reduced molybdenum oxide (MoOx) shell is introduced that is grown on top of a dendritic nickel foam core (NiNF). The resulting MoOx/NiNF material is prepared via a facile, two‐step electrodeposition strategy using commercially available, low‐cost precursors. This catalytic material displays a remarkable faradaic efficiency (FE) of 99% at −0.5 V versus RHE and a high ammonia (NH3) yield rate of up to 4.29 mmol h−1 cm−2 at −1.0 V versus RHE in neutral media. Most importantly, MoOx/NiNF exhibits exceptional stability for the nitrate reduction reaction (NO3RR), maintaining operation for over 3100 h at a high current density of −650 mA cm−2, with a yield rate of 2.6 mmol h−1 cm−2 and a stable average NH3 FE of ≈83%. Through combined XPS and in situ Raman spectroscopy it is shown that the pronounced affinity of MoOx/NiNF for nitrate is associated with a substantial presence of oxygen vacancies within the material. [ABSTRACT FROM AUTHOR]

AbstractThe limitation of water and unfavorable soil conditions for plant’s nutrient absorption present a hurdle to the growth and yield of red beans under drought stress conditions. Micronutrients, particularly zinc and molybdenum, show promise in mitigating drought effects. Various irrigation levels (100% and 70% of field capacity) and nutrient application methods were tested in the field (two locations) and the greenhouse in 2022. Parameters such as photosynthesis, gas exchange, root characteristics, nitrate reductase, antioxidant enzymes, and yield were evaluated. The combination of nano zinc priming (NZnP 150 mg L−1) and foliar spraying of nano zinc (FSNZn 0.04 mg L−1) at 100% field capacity resulted in the highest photosynthesis, gas exchange, and yield. Water stress increased the activity of antioxidant enzymes. In greenhouse test, NZnP (150 mg L−1) + FSNZn (0.04 mg L−1) at 100% field capacity promoted maximum root length and nitrate reductase activity. Overall, NZnP + FSNZn at 100% field capacity proved most effective for morphological and biochemical root characteristics and yield. Drought stress reduced red bean yield, but NZnP + FSNZn mitigated some adverse effects. Nano forms of zinc and molybdenum were more effective in mitigating drought stress. Location significantly influenced plant development, with lower temperatures delaying reproductive phase transition, leading to better vegetative and reproductive traits compared to the location with higher temperature. [ABSTRACT FROM AUTHOR]

Microbial communities are fundamental components driving critical biogeochemical carbon (C), nitrogen (N) and sulfur (S) cycles in groundwater ecosystems. The reduction–oxidation (redox) potential is one important environmental factor influencing the microbial community composition. Here, we developed a bio-trap method using in-situ sediment as a matrix to collect aquifer sediment samples and evaluate the response of microbial composition and C/N/S cycling functions to redox variations created by providing sole O2, joint O2 and H2, and sole H2 to three wells. Illumina sequencing analyses showed that the microbial communities in the bio-trap sediment could respond quickly to redox changes in the wells, demonstrating that this bio-trap method is promising for detecting microbial variation in the aquifer sediment. The microbial metabolic functions related to C, N and S cyclings and organic pollutants degradation were predicted by the Kyoto Encyclopedia of Genes and Genomes (KEGG) approach. It was found that the joint O2 and H2 injection produced medium oxidation–reduction potential (ORP −346 and −614 mV) and enhanced more microbial functions than sole O2 or H2, which mainly include oxidative phosphorylation, most carbon source metabolism, various pollutants degradation, and nitrogen and sulfur metabolism. Moreover, the functional genes encoding phenol monooxygenase, dioxygenase, nitrogen fixation, nitrification, aerobic and anaerobic nitrate reductase, nitrite reductase, nitric oxide reductase, and sulfur oxidation increased. These findings tell us the contaminant bioremediation and N, S metabolism can be promoted by adjusting ORP realised by injecting joint O2 and H2. [ABSTRACT FROM AUTHOR]

Heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria are the key functional microorganisms needed to achieve simultaneous nitrification and denitrification (SND). In this study, 25 strains of HN-AD bacteria were successfully isolated from a stable landfill leachate biochemical treatment system, of which 10 strains belonged to Firmicutes and 15 strains belonged to Proteobacteria. Bacillus subtilis F4 and Alcaligenes faecalis P4 displayed good tolerance at a wide range of ammonia nitrogen (NH4+-N) concentrations. When the C/N ratio was 20, the removal rates of ammonia nitrogen were 90.1% and 89.5%, and the chemical oxygen demand (COD) removal rates were 92.4% and 93.9%, respectively. The napA gene encoding periplasmic nitrate reductase (Nap) and the nirS gene encoding nitrite reductase (Nir) were detected, and nitrogen balance showed assimilation and HN-AD was the main nitrogen metabolism mode in both strains. The use of immobilization materials could increase removal rate of ammonia nitrogen by 21.1% and 29.6%, respectively. The research results of this work can provide theoretical basis and technical support for the practical application of HN-AD bacteria to enhance the treatment of high ammonia nitrogen wastewater with high efficiency and low consumption. [ABSTRACT FROM AUTHOR]

Plant defense responses to the soil-borne fungus Verticillium longisporum causing stem stripe disease on oilseed rape (Brassica napus) are poorly understood. In this study, a population of recombinant inbred lines (RILs) using the Arabidopsis accessions Sei-0 and Can-0 was established. Composite interval mapping, transcriptome data, and T-DNA mutant screening identified the NITRATE/PEPTIDE TRANSPORTER FAMILY 5.12 (AtNPF5.12) gene as being associated with disease susceptibility in Can-0. Co-immunoprecipitation revealed interaction between AtNPF5.12 and the MAJOR LATEX PROTEIN family member AtMLP6, and fluorescence microscopy confirmed this interaction in the plasma membrane and endoplasmic reticulum. CRISPR/Cas9 technology was applied to mutate the NPF5.12 and MLP6 genes in B. napus. Elevated fungal growth in the npf5.12 mlp6 double mutant of both oilseed rape and Arabidopsis demonstrated the importance of these genes in defense against V. longisporum. Colonization of this fungus depends also on available nitrates in the host root. Accordingly, the negative effect of nitrate depletion on fungal growth was less pronounced in Atnpf5.12 plants with impaired nitrate transport. In addition, suberin staining revealed involvement of the NPF5.12 and MLP6 genes in suberin barrier formation. Together, these results demonstrate a dependency on multiple plant factors that leads to successful V. longisporum root infection. [ABSTRACT FROM AUTHOR]

Human mitochondria contain a molybdoprotein capable of reducing amidoximes using cytochrome b5/cytochrome b5 reductase (Cb/CbR). This 'amidoxime reducing component' (ARC) also reduces nitrite to nitric oxide (NO). In the plant kingdom, distinct functions have been suggested for ARCs. Thus, the single ARC of Chlamydomonas reinhardtii (crARC) reduces nitrite to NO by taking electrons from nitrate reductase (NR). Therefore, it was proposed that a dual NR/crARC system can generate NO under physiological conditions and the crARC was renamed to 'NO‐forming nitrite reductase' (NOFNiR). In contrast to this, the two ARC enzymes from Arabidopsis thaliana were not found to produce NO in vitro at physiological nitrite concentrations, suggesting a different, as yet unknown, function in vascular plants. Here, we have investigated the two ARCs of Lotus japonicus (LjARCs) to shed light on this controversy and to examine, for the first time, the distribution of ARCs in plant tissues. The LjARCs are localized in the cytosol and their activities and catalytic efficiencies, which are much higher than those of A. thaliana, are consistent with a role as NOFNiR. LjARCs are prone to S‐nitrosylation in vitro by S‐nitrosoglutathione and this post‐translational modification drastically inhibits their activities. The enzymes are mainly expressed in flowers, seeds and pods, but are absent in nodules. LjARCs are active with NR and Cb/CbR as electron‐transferring systems. However, the LjNR mRNA levels in seeds and pods are negligible, whereas our proteomic analyses show that pods contain the two ARCs, Cb and CbR. We conclude that LjARCs may play a role as NOFNiR by receiving electrons from the Cb/CbR system but do not act in combination with NR. [ABSTRACT FROM AUTHOR]

Nitrate is a nutrient and signal that regulates gene expression. The nitrate response has been extensively characterized at the organism, organ, and cell‐type‐specific levels, but intracellular mRNA dynamics remain unexplored. To characterize nuclear and cytoplasmic transcriptome dynamics in response to nitrate, we performed a time‐course expression analysis after nitrate treatment in isolated nuclei, cytoplasm, and whole roots. We identified 402 differentially localized transcripts (DLTs) in response to nitrate treatment. Induced DLT genes showed rapid and transient recruitment of the RNA polymerase II, together with an increase in the mRNA turnover rates. DLTs code for genes involved in metabolic processes, localization, and response to stimulus indicating DLTs include genes with relevant functions for the nitrate response that have not been previously identified. Using single‐molecule RNA FISH, we observed early nuclear accumulation of the NITRATE REDUCTASE 1 (NIA1) transcripts in their transcription sites. We found that transcription of NIA1, a gene showing delayed cytoplasmic accumulation, is rapidly and transiently activated; however, its transcripts become unstable when they reach the cytoplasm. Our study reveals the dynamic localization of mRNAs between the nucleus and cytoplasm as an emerging feature in the temporal control of gene expression in response to nitrate treatment in Arabidopsis roots. [ABSTRACT FROM AUTHOR]

Flavonoids (especially anthocyanins and catechins) and amino acids represent a high abundance of health-promoting metabolites. Although we observed abscisic acid accumulation in purple leaves and low levels in albino tea leaves, the specific mechanism behind its impact on flavor compounds remains unclear. In this study, we treated tea leaves with exogenous abscisic acid and abscisic acid biosynthesis inhibitors (Flu), measured physiological indicators and conducted comprehensive transcriptomic and metabolomic analyses to elucidate the potential mechanisms underlying color change. Our results demonstrate that abscisic acid treatment induces purple coloration, while Flu treatment causes discoloration in tea leaves. Metabolomic analysis revealed higher levels of four anthocyanins and six catechins in the group treated with abscisic acid in comparison with the control group. Additionally, there was a notable increase in 15 amino acids in the Flu-treated group. Notably, the levels of flavonoids and amino acids showed an inverse relationship between the two treatments. Transcriptomic comparison between the treatments and the control group revealed upregulation of differentially expressed genes encoding dihydroflavonol reductase and uridine diphosphate-glycose flavonoid glycosyltransferase in the abscisic acid-treated group, leading to the accumulation of identified anthocyanins and catechins. In contrast, differentially expressed genes encoding nitrate reductase and nitrate transporter exhibited elevated expression in the group treated with Flu, consequently facilitating the accumulation of amino acids, specifically L-theanine and L-glutamine. Furthermore, our co-expression network analysis suggests that MYB and bHLH transcription factors may play crucial roles in regulating the expression of differentially expressed genes involved in the biosynthesis of flavonoids and amino acids. This study provides insights for targeted genetic engineering to enhance the nutritional and market value of tea, together with the potential application of purple and albino tea leaves as functional beverages. It also offers guidance for future breeding programs and production. [ABSTRACT FROM AUTHOR]

AbstractThis work was conducted to evaluate the effect of N source (NH4+/NO3-) and the implication of NH4+-induced acidification on plant development in Arabidopsis thaliana. seedlings were hydroponically cultivated during 21 days under three ratios of NO3−/NH4+ (mM); 2.5/0.0; 1.25/1.25, and 0.0/2.5. For each ratio, plants were cultivated under not controlled pH and adjusted pH at 6.2. Ammonium-fed plants (0.0/2.5) showed chlorosis if cultivated under uncontrolled pH. This symptom was associated with suppressions in plant growth, chlorophyll and iron contents as well as shoots hydration and nutrient concentration. Growth was limited with increasing NH4+ medium-concentration. At pH 6.2, plants receiving only NH4+ produced the same biomass as NO3-fed ones. The mineral disturbances in plants grown on strictly NH4+-medium (0.0/2.5) were alleviated under controlled pH. The activities of nitrate reductase (NR) and nitrite reductase (NIR) were lower in plants amended only with NH4+ under uncontrolled pH. At adjusted pH, the NR activity was ameliorated but that of NIR was not ameliorated, suggesting hence that NR activity depended on medium pH but that of NIR was related only to the pool of NO2-. In conclusion, this work demonstrated that the adjustment of pH at 6.2 mitigated significantly the toxic effects of ammonium to A. thaliana. [ABSTRACT FROM AUTHOR]

The purpose of this study was to explore the carbon and nitrogen metabolism mechanisms of sand-cultivated cucumbers under different deficit irrigation–nitrogen management strategies and provide a theoretical basis for their greenhouse management. This study set up two factors, the deficit irrigation level and the nitrogen application rate, and conducted an experiment on deficit irrigation–nitrogen coupling of sand-cultivated cucumbers using a quadratic saturation D–optimal design. Seven treatments were set up in the experiment, to measure the soluble sugar and protein contents, as well as the activity of key enzymes for carbon and nitrogen metabolism at five different growth stages. The results indicate that the 80% irrigation with 623 kg N hm−2 (IN4) treatment significantly improved the soluble sugar, protein, and actual leaf nitrogen contents of cucumber at the five different growth stages and, as a result, achieved higher sucrose synthase (SS) and sucrose phosphate synthase (SPS) activities in the cucumber leaves. Furthermore, such improvements were due to the reduction in oxidative damage of sand–cultivated cucumber at various growth stages. The IN4 and 89% irrigation with 1250 kg N hm−2 (IN5) treatments significantly increased the activities of RuBisCO, catalase (CAT), peroxidise (POD), and superoxide dismutase (SOD) at various growth stages of sand-cultivated cucumber. The higher activities of glutamate dehydrogenase (GLDH), glutamate synthase (GOGAT), nitrate reductase (NR), glutamine synthase (GS), acid invertase enzyme (AIE), neutral invertase enzyme (NIE), and better antioxidative enzyme activities were recorded under the IN4 treatments at various growth stages, which effectively improve (69.6%) cucumber yield. The soil properties, carbon and nitrogen metabolism, and antioxidant metabolism were positively correlated with sand-cultivated cucumber yield in a greenhouse. We concluded that the IN4 treatment was the better deficit irrigation–nitrogen management strategy because it considerably improves carbon and nitrogen metabolism, antioxidant enzyme activities, and sand–cultivated cucumber yield in a greenhouse. [ABSTRACT FROM AUTHOR]

Reduced glutathione (γ-glutamyl-cysteinyl-glycine, GSH), the primary non-protein sulfhydryl group in organisms, plays a pivotal role in the plant salt stress response. This study aimed to explore the impact of GSH on the photosynthetic apparatus, and carbon assimilation in tomato plants under salt stress, and then investigate the role of nitric oxide (NO) in this process. The investigation involved foliar application of 5 mM GSH, 0.1% (w/v) hemoglobin (Hb, a nitric oxide scavenger), and GSH+Hb on the endogenous NO levels, rapid chlorophyll fluorescence, enzyme activities, and gene expression related to the Calvin cycle in tomato seedlings (Solanum lycopersicum L. cv. ‘Zhongshu No. 4’) subjected short-term salt stress (100 mM NaCl) for 24, 48 and 72 hours. GSH treatment notably boosted nitrate reductase (NR) and NO synthase (NOS) activities, elevating endogenous NO signaling in salt-stressed tomato seedling leaves. It also mitigated chlorophyll fluorescence (OJIP) curve distortion and damage to the oxygen-evolving complex (OEC) induced by salt stress. Furthermore, GSH improved photosystem II (PSII) electron transfer efficiency, reduced QA- accumulation, and countered salt stress effects on photosystem I (PSI) redox properties, enhancing the light energy absorption index (PIabs). Additionally, GSH enhanced key enzyme activities in the Calvin cycle and upregulated their genes. Exogenous GSH optimized PSII energy utilization via endogenous NO, safeguarded the photosynthetic reaction center, improved photochemical and energy efficiency, and boosted carbon assimilation, ultimately enhancing net photosynthetic efficiency (Pn) in salt-stressed tomato seedling leaves. Conversely, Hb hindered Pn reduction and NO signaling under salt stress and weakened the positive effects of GSH on NO levels, photosynthetic apparatus, and carbon assimilation in tomato plants. Thus, the positive regulation of photosynthesis in tomato seedlings under salt stress by GSH requires the involvement of NO. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Soil Sciences & Agricultural Engineering is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Electrocatalytic nitrate reduction reaction (e-NO3RR) offers a promising alternative method for nitrogen cycling and ammonia (NH3) production under ambient conditions. However, the method is still in the dilemma of lowering the reaction overpotential and increasing the reaction activity. We successfully developed the composition-adjustable Co6Mo6C/Co/N-doped carbon (NC) catalysts by in situ carbonization of Co-based metal-organic framework (MOF) with the constrained phosphomolybdic acid. After adjusting the ratio of Co0 and Co6Mo6C, Co6Mo6C/Co/NC-3 could satisfy both NO3− conversion at low potential and NHx hydrogenation, and synthesize ammonia efficiently through the synergistic effect of Co0 and Co6Mo6C. It achieved an ammonia yield rate as 1233.2 µg·h−1·mgcat−1 and Faradaic efficiency of NH4+ 93.6% at −0.33 V vs. reversible hydrogen electrode (RHE). Importantly, density functional theory (DFT) calculations and experimental results have demonstrated for the first time the excellent adsorption of nitrite (NO2−) by the Mo sites of Co6Mo6C during e-NO3RR, avoiding the undesirable accumulation of NO2−. [ABSTRACT FROM AUTHOR]

In the soils of vanadium (V) smelters, a diverse array of microorganisms relies on metabolic activities for survival amid stress. However, the characteristics and functions of soil microbiomes in V mining environments remain unexplored on a continental scale. This study thoroughly investigates the microbial diversity, community assembly, and functional potential of soil microbiome across 90 V smelters in China. Alpha diversity decreases significantly along the V gradient, with V emerging as the primary factor influencing community structure, followed by other environmental, climatic, and geographic factors. The null model reveals that V induces homogeneous selection, shaping co‐occurrence patterns and leading to increased number of positive associations, particularly with keystone genera such as f_Gemmatimonadaceae, Nocardioides, Micromonospora, and Rubrobacter under higher V concentrations (>559.6 mg/kg). Moreover, a metagenomic analysis yields 67 metagenome‐assembled genomes, unraveling the potential metabolic pathways of keystone taxa and their likely involvement in the V(V) reduction process. Nitrate and nitrite reductase (nirK, narG), and mtrABC are found to be taxonomically affiliated with Micromonospora. sp, FEN‐1250. sp, Nocardioides. sp, etc. Additionally, the reverse citric acid cycle (rTCA) likely serves as the primary carbon fixation pathway, synthesizing alternative energy for putative V reducers, highlighting a potentially synergistic relationship between autotrophic and heterotrophic processes that supports microbial survival. Our findings comprehensively uncover the driving forces behind soil community variation under V stress, revealing robust strategies possibly employed by indigenous microorganisms to mitigate the impact of V. These insights hold potential for applications in bioremediation. Plain Language Summary: Vanadium, a byproduct of anthropogenic smelting, is predominantly sequestered in the soil, where soil microorganisms act as vital indicators of ecosystem health under pollutant exposure. The soil layer not only functions as a primary repository but also provides buffering capacity, impeding the migration of vanadium into groundwater. Study results reveal that the occurrence and abundance of microorganisms are collectively influenced by vanadium levels, environmental factors, geographical location, and climatic conditions. Species distribution is shaped by the interplay of vanadium levels and microbial migration across geographic gradients. In heavily contaminated soil, microbial interdependence is markedly heightened, especially with vanadium‐tolerant species, compared with relatively healthy soil, supporting diverse nutrient utilization for microbial growth. Keystone taxa in the community network assume pivotal roles in nutrient cycling, energy synthesis, and governing the bioreduction of high‐valent vanadium. These activities may mitigate the impact of vanadium on the soil environment near smelter sites. Key Points: Vanadium, environmental parameters, climatic, and geographic factors jointly explained the community variationElevated vanadium content promoted deterministic community assembling processes and strengthened the interspecific microbial associationKeystone taxa facilitated community survival via both putative autotrophic and heterotrophic pathways [ABSTRACT FROM AUTHOR]

Increased nitrogen deposition is a key feature of global climate change, however, its effects on the structure and assembling mechanisms of the nitrogen-fixing bacteria present at the root surface remain to be elucidated. In this pursuit, we used NH4NO3 to simulate nitrogen deposition in a 10-year-old Camellia oleifera plantation, and set up four deposition treatments, including control N0 (0 kg N hm-2 a-1), low nitrogen N20 (20 kg N hm-2 a-1), medium nitrogen N40 (40 kg N hm-2 a-1) and high nitrogen N160 (160 kg N hm-2 a-1). The results showed that nitrogen deposition affected the soil nitrogen content and the structure of the nitrogen-fixing bacterial community. Low nitrogen deposition was conducive for nitrogen fixation in mature C. oleifera plantation. With increasing nitrogen deposition, the dominant soil nitrogen-fixing bacterial community shifted from Desulfobulbaceae to Bradyrhizobium. When nitrogen deposition was below 160 kg N hm-2 a-1, the soil organic matter content, total nitrogen content, nitrate nitrogen content, ammonium nitrogen content, urease activity, soil pH and nitrate reductase activity influenced the composition of the nitrogen-fixing bacterial community, but the stochastic process remained the dominant factor. The results indicate that the strains of Bradyrhizobium japonicum and Bradyrhizobium sp. ORS 285 can be used as indicator species for excessive nitrogen deposition. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Lignocellulosic materials, made up of cellulose, hemicellulose, and lignin, constitute some of the most prevalent types of biopolymers in marine ecosystems. The degree to which marine microorganisms participate in the breakdown of lignin and their impact on the cycling of carbon in the oceans is not well understood. Strain LCG002, a novel Marivivens species isolated from Lu Chao Harbor's intertidal seawater, is distinguished by its ability to metabolize lignin and various aromatic compounds, including benzoate, 3-hydroxybenzoate, 4-hydroxybenzoate and phenylacetate. It also demonstrates a broad range of carbon source utilization, including carbohydrates, amino acids and carboxylates. Furthermore, it can oxidize inorganic gases, such as hydrogen and carbon monoxide, providing alternative energy sources in diverse marine environments. Its diversity of nitrogen metabolism is supported by nitrate/nitrite, urea, ammonium, putrescine transporters, as well as assimilatory nitrate reductase. For sulfur assimilation, it employs various pathways to utilize organic and inorganic substrates, including the SOX system and DSMP utilization. Overall, LCG002's metabolic versatility and genetic profile contribute to its ecological significance in marine environments, particularly in the degradation of lignocellulosic material and aromatic monomers. [ABSTRACT FROM AUTHOR]

The unique positioning of mangrove ecosystems between land and sea makes them vital in the nitrogen cycle. The role of nitrification in the nitrogen cycle is important to provide nitrogen compounds readily absorbed by mangrove plants. Nevertheless, the nitrification process and nitrifying bacteria in mangrove areas have yet to be comprehensively understood. The primary objective of this study is to provide comprehensive analysis of nitrifying bacteria in mangrove sediments by conducting a systematic review. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses method is used as a guide to help report reviews systematically and has a flow chart to show the process of selecting relevant studies. Data collection was carried out by utilizing 6 databases and journal search engines including Scopus, PubMed, ResearchGate, Google Scholar, and Springer in order to achieve more comprehensive findings. This study employed the widely recognized and commonly used technique of defining the review's scope in a focused manner by first identifying the population, intervention, comparison, and outcome. This study identified 358 studies, and 31 studies were included in the review after screening. Based on the screening results, research on nitrifying bacteria in mangrove sediments is geographically limited to several countries such as Indonesia, Vietnam, Thailand, China, Mexico, the United States, India, and Saudi Arabia. This study vealed that there is a high level of diversity among nitrifying bacteria in mangrove sediment, with five distinct groups identified: ammonia oxidizing bacteria, nitrite oxidizing bacteria, anammox bacteria, and comammox bacteria, a recently identified group. In carrying out changes in nitrogen compounds, nitrifying bacteria use functional genes from different steps of the nitrification process, such as nitrogenase, ammonia monooxygenase subunit A, nitrite oxidoreductase alpha subunit, nitrate reductase alpha chain, nitrite reductase, nitric oxide reductase, nitrous oxide reductase, hydrazine synthase, hydrazine oxidoreductase and hydroxylamine oxidoreductase genes. Ammonia-oxidizing bacteria were the predominant group in general, but various nitrifying bacteria groups were distributed diversely across different mangrove environments. This study also indicated the vegetation type and the distribution of nitrifying bacteria in mangrove sediments. The depth of these sediments typically varies from 0 to 60 centimeters, with most samples taken at a depth of 0 to 20 centimeters. The type of vegetation at the sampling location is dominated by species of Kandelia candel, Avicennia marina, Kandelia obovata, and Rhizophora mangle. Limitations regarding research on nitrifying bacteria in mangrove sediments provide opportunities for in-depth study. This comprehensive review provides an in-depth overview of the variety and spread of nitrifying bacteria, highlighting their role in nitrogen cycling and emphasizing the potential for discovering new nitrifying bacteria in mangrove sediments. [ABSTRACT FROM AUTHOR]

In savanna ecosystems, the seasonal effects of nitrogen forms and availability, as well as their utilization by plants, influence the abundance and distribution of herbaceous species in grassland communities. This study examines seasonal effects on nitrogen availability and utilization by native grass species in the Cerrado, a savanna ecosystem in Brazil. Ammonium and nitrate levels in soil, nitrate acquisition and transport, and Nitrate Reductase Activity (NRA) in different plant parts during dry and wet periods were assessed. Results indicated higher soil nitrate availability during the wet period, influenced by precipitation, with leaves showing a higher nitrate content compared to roots. There was seasonal modulation in nitrate reduction, with leaves being the primary site during the dry period and roots during the wet period. The studied grass species exhibited heterogeneous responses to seasonal nitrogen availability, potentially affecting community abundance patterns. Findings suggest that edaphoclimatic seasonality plays a crucial role in nitrogen distribution and utilization capacity by grass plants in the Cerrado, contributing to the understanding of these ecosystems’ ecology.

The presence of alkene moieties in fatty acids of (phospho)lipids and cholesterol derivatives makes them highly susceptible to damage by nitrate radicals (NO3⋅), potentially formed through simultaneous exposure to the environmental air pollutants nitrogen dioxide (NO2⋅) and ozone (O3). Absolute rate coefficients derived from reactions with simplified model systems range from 4 to 8×109 M−1 s−1 in acetonitrile, ranking among the highest determined for NO3⋅ reactions with biomolecules in solution to date. Alkenes featuring an electron‐withdrawing carbonyl substituent also display notable reactivity with k values of (2.5±1.0)×108 M−1 s−1. Calculations suggest that these reactions are initiated by oxidative electron transfer (ET) involving the C=C bond, followed by recombination of the resulting alkene radical cation with nitrate anion (NO3−) to form the nitrate adduct radical as the kinetically controlled product. Conversely, saturated fatty acid derivatives and cholestanol react with NO3⋅ through hydrogen atom transfer (HAT) with rate coefficients of 106–107 M−1 s−1, indicating that biomolecules with a considerable number of non‐ or moderately activated sp3 C−H bonds are also highly susceptible to NO3⋅ attack. These findings underscore the potential health hazards associated with exposure to combined NO2⋅ and O3 gases. [ABSTRACT FROM AUTHOR]

Assimilatory nitrate reduction and methane (CH4) oxidation by bacteria play important roles in carbon (C) and nitrogen (N) biogeochemical cycles. Here, an investigation of enzymatic assimilatory nitrate reduction and CH4 oxidation by Methylobacter sp. YHQ from the wetlands is presented, specifically concentrating on N and oxygen (O) isotope fractionation with various initial nitrate and oxygen concentrations. The N enrichment factors (15εassimilation) increased from 4.2 ± 0.7‰ to 6.9 ±1.3‰ and the O isotope enrichment factors (18εassimilation) increased from 2.7 ± 0.9‰ to 4.7 ± 0.8‰ during nitrate assimilation when initial nitrate concentrations increased from 0.9 mM to 2 mM. Similar 18ε and 15ε values were observed at different oxygen concentrations. The values of 18ε and 15ε provided vital parameters for the assessment of assimilatory nitrate reduction via the Rayleigh equation approach. The ratios of O and N isotope enrichment factors (18ε:15ε)assimilation ranged from 0.64 ± 0.15 to 0.74 ± 0.18 during nitrate assimilation by Methylobacter sp. YHQ with Nas, which were different from (18ε:15ε)assimilation for assimilatory eukaryotic nitrate reductase (eukNR) from literature data. Thus, N and O isotope fractionation could be useful tools to distinguish eukNR from Nas during nitrate assimilation. Additionally, the rates of CH4 oxidation and nitrate reduction were evaluated with a reaction-based kinetic model, and it quantitatively described the enzymatic reactions of nitrate assimilation. Combining dual N-O isotope analysis with kinetic modeling provides new insights into the microbially driven C-N interactions. Highlights: • Effects of nitrate and oxygen concentrations on isotope fractionation were revealed. • The (18ε:15ε)assimilation ratios induced by freshwater bacteria were 0.64 ± 0.15–0.74 ± 0.18. • Dual N-O isotopes are useful approaches for distinguishing Nas from eukNR. • The rates of CH4 oxidation and nitrate reduction can be predicted using a kinetic model. [ABSTRACT FROM AUTHOR]

In recent years, golden tides caused by floating Sargassum have induced severe ecological disasters globally. Eutrophication is a significant factor contributing to the massive spread of Sargassum golden tides. Furthermore, the thalli of Sargassum that float on the ocean surface are subjected to more ultraviolet radiation (UVR). The coupled impact of eutrophication and UVR on the photosynthetic physiology of golden tide species remains unclear. In this study, the thalli of Sargassum horneri, known to cause golden tide, were cultured and acclimated to three distinct nitrogen (N) conditions (natural seawater, NSW; NH4 +-N enrichment; and NO3 -N enrichment) for 6 days. Subsequently, the thalli were exposed to two different radiation treatments (photosynthetically active radiation (150 W m-2), PAR, 400-700 nm; PAR (150 W m-2) + UVR (28 W m-2), 280-700 nm) for 120 min, to investigate the photosynthetic effects of UVR and N on this alga. The findings demonstrated that exposure to UVR impeded the photosynthetic capacity of S. horneri, as evidenced by a decrease in the maximum photochemical quantum yield (Fv/Fm), photosynthetic efficiency (a) and chlorophyll content. Under diverse Nenrichment conditions, the alga tended to adopt various strategies to mitigate the adverse effects of UVR. NH4 +-enrichment dissipated excess UVR energy through a greater increase in non-photochemical quenching (NPQ). While NO3 - enrichment protected alga by enhancing N assimilation (higher nitrate reductase activity (NRA) and soluble protein content), and maintained a stable energy captured per unit reaction center for electron transfer (ET0/RC) and a higher net photosynthetic rate. Although different N enrichments could not completely offset the damage caused by UV radiation, they secured the photoprotective ability of S. horneri in several ways. [ABSTRACT FROM AUTHOR]

Summary: Seminal roots play a critical role in water and nutrient absorption, particularly in the early developmental stages of wheat. However, the genes responsible for controlling SRN in wheat remain largely unknown.Genetic mapping and functional analyses identified a candidate gene (TraesCS3D01G137200, TaSRN‐3D) encoding a Ser/Thr kinase glycogen synthase kinase 3 (STKc_GSK3) that regulated SRN in wheat. Additionally, experiments involving hormone treatment, nitrate absorption and protein interaction were conducted to explore the regulatory mechanism of TaSRN‐3D.Results showed that the TaSRN‐3D4332 allele inhibited seminal roots initiation and development, while loss‐of‐function mutants showed significantly higher seminal root number (SRN). Exogenous application of epi‐brassinolide could increase the SRN in a HS2‐allelic background. Furthermore, chlorate sensitivity and 15N uptake assays revealed that a higher number of seminal roots promoted nitrate accumulation. TaBSR1 (BIN2‐related SRN Regulator 1, orthologous to OsGRF4/GL2 in rice) acts as an interactor of TaSRN‐3D and promotes TaBSR1 degradation to reduce SRN.This study provides valuable insights into understanding the genetic basis and regulatory network of SRN in wheat, highlighting their roles as potential targets for root‐based improvement in wheat breeding. [ABSTRACT FROM AUTHOR]

Salt stress seriously affects crop growth, leading to a decline in crop quality and yield. Application of exogenous substances to improve the salt tolerance of crops and promote their growth under salt stress has become a widespread and effective means. Eugenol is a small molecule of plant origin with medicinal properties such as antibacterial, antiviral, and antioxidant properties. In this study, tobacco seedlings were placed in Hoagland's solution containing NaCl in the presence or absence of eugenol, and physiological indices related to stress tolerance were measured along with transcriptome sequencing. The results showed that eugenol improved the growth of tobacco seedlings under salt stress. It promoted carbon and nitrogen metabolism, increased the activities of nitrate reductase (NR), sucrose synthase (SS), and glutamine synthetase (GS) by 31.03, 5.80, and 51.06%. It also activated the enzymatic and non-enzymatic antioxidant systems, reduced the accumulation of reactive oxygen species in the tobacco seedlings, and increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) by 24.38%, 18.22%, 21.60%, and 28.8%, respectively. The content of glutathione (GSH) was increased by 29.49%, and the content of superoxide anion (O2−) and malondialdehyde (MDA) were reduced by 29.83 and 33.86%, respectively. Promoted osmoregulation, the content of Na+ decreased by 34.34, K+ increased by 41.25%, and starch and soluble sugar increased by 7.72% and 25.42%, respectively. It coordinated hormone signaling in seedlings; the content of abscisic acid (ABA) and gibberellic acid 3 (GA3) increased by 51.93% and 266.28%, respectively. The transcriptome data indicated that the differentially expressed genes were mainly enriched in phenylpropanoid biosynthesis, the MAPK signaling pathway, and phytohormone signal transduction pathways. The results of this study revealed the novel role of eugenol in regulating plant resistance and provided a reference for the use of exogenous substances to alleviate salt stress. [ABSTRACT FROM AUTHOR]

Water deficiency has been recognized as a major abiotic stress that causes losses in maize crops around the world. The maize crop is very important due to the range of products that are derived from this plant. A potential way to reduce the damages caused by water deficiency in maize crops is through the association with plant growth-promoting bacteria (PGPB) and arbuscular mycorrhizal fungi (AMF). To define the mechanisms developed by associative PGPB and AMF in maize that are involved in protection against moderate drought (MD), this study evaluated the biometrical, anatomical, biochemical, and physiological parameters of maize grown under MD and inoculated with different PGPB (Azospirillum brasilense strain Ab-V5 and Bacillus sp. strain ZK) and with AMF. The relative water content did not change in the treatments. The association with ZK increased the shoot:total ratio, total dry weight, maximum quantum yield of photosystem II, vascular cylinder thickness, and vascular cylinder area. The Ab-V5 inoculation led to an increment in root dry weight, the area of metaxylem vessel elements, and nitrate reductase activity. The AMF association did not lead to changes in the measured parameters. The results indicate that the association with PGPB is a relevant alternative to contribute to reducing losses in maize crops under drought. However, AMF is not indicated for this crop under drought. [ABSTRACT FROM AUTHOR]

Mycobacterium abscessus (Mab) is an opportunistic pathogen afflicting individuals with underlying lung disease such as Cystic Fibrosis (CF) or immunodeficiencies. Current treatment strategies for Mab infections are limited by its inherent antibiotic resistance and limited drug access to Mab in its in vivo niches resulting in poor cure rates of 30-50%. Mab's ability to survive within macrophages, granulomas and the mucus laden airways of the CF lung requires adaptation via transcriptional remodeling to counteract stresses like hypoxia, increased levels of nitrate, nitrite, and reactive nitrogen intermediates. Mycobacterium tuberculosis (Mtb) is known to coordinate hypoxic adaptation via induction of respiratory nitrate assimilation through the nitrate reductase narGHJI. Mab, on the other hand, does not encode a respiratory nitrate reductase. In addition, our recent study of the transcriptional responses of Mab to hypoxia revealed marked down-regulation of a locus containing putative nitrate assimilation genes, including the orphan response regulator nnaR (nitrate/nitrite assimilation regulator). These putative nitrate assimilation genes, narK3 (nitrate/nitrite transporter), nirBD (nitrite reductase), nnaR, and sirB (ferrochelatase) are arranged contiguously while nasN (assimilatory nitrate reductase identified in this work) is encoded in a different locus. Absence of a respiratory nitrate reductase in Mab and down-regulation of nitrogen metabolism genes in hypoxia suggest interplay between hypoxia adaptation and nitrate assimilation are distinct from what was previously documented in Mtb. The mechanisms used by Mab to fine-tune the transcriptional regulation of nitrogen metabolism in the context of stresses e.g. hypoxia, particularly the role of NnaR, remain poorly understood. To evaluate the role of NnaR in nitrate metabolism we constructed a Mab nnaR knockout strain (MabΔnnaR) and complement (MabΔnnaR+C) to investigate transcriptional regulation and phenotypes. qRT-PCR revealed NnaR is necessary for regulating nitrate and nitrite reductases along with a putative nitrate transporter. Loss of NnaR compromised the ability of Mab to assimilate nitrate or nitrite as sole nitrogen sources highlighting its necessity. This work provides the first insights into the role of Mab NnaR setting a foundation for futurework investigating NnaR's contribution to pathogenesis. [ABSTRACT FROM AUTHOR]

Despite global warming, the response of rice yield to long-term warming in cool regions and its physiological mechanisms remain unknown. This study used the widely cultivated japonica rice Jiyang100 in Northeast China. Taking rice grown under natural temperatures as a control (CK), field warming treatments were conducted at the tillering-panicle initiation (T1), whole growth (T2), and grain-filling (T3) stages. The positive effects of T1, T2, and T3 on the total number of spikelets per hole increased the yield in both years, with average increases of 11.5%, 9.9% and 6.5% compared to CK, respectively. Warming treatments improved the stay-green traits, photosynthesis, sucrose synthesis, and nitrogen metabolism of rice. The yield was positively correlated with the relative chlorophyll content (SPAD), soluble sugar content, sucrose content, and the activities of sucrose phosphate synthase (SPS), nitrate reductase (NR), glutamine synthetase (GS), glutamine oxoglutarate aminotransferase (GOGAT) in flag leaves. In addition, SPAD had a positive correlation with soluble sugar content, soluble protein content, and the activities of NR, GS, GOGAT, glutamate dehydrogenase (GDH), but a negative correlation with acid invertase (AI) activity. The stay-green ability was positively correlated to the net photosynthetic rate (Pn), soluble sugar content and soluble protein content. The coupling interactions of stay-green traits, nitrogen and carbon metabolism increased the yield potential and yield supply capacity, increased yield under long-term warming conditions in the cool regions. Under gradual warming, the physiological response of rice in cool regions promotes plant growth and development, thereby increasing yield. [ABSTRACT FROM AUTHOR]

Periplasmic nitrate reductase NapA from Campylobacter jejuni (C. jejuni) contains a molybdenum cofactor (Moco) and a 4Fe–4S cluster and catalyzes the reduction of nitrate to nitrite. The reducing equivalent required for the catalysis is transferred from NapC → NapB → NapA. The electron transfer from NapB to NapA occurs through the 4Fe–4S cluster in NapA. C. jejuni NapA has a conserved lysine (K79) between the Mo-cofactor and the 4Fe–4S cluster. K79 forms H-bonding interactions with the 4Fe–4S cluster and connects the latter with the Moco via an H-bonding network. Thus, it is conceivable that K79 could play an important role in the intramolecular electron transfer and the catalytic activity of NapA. In the present study, we show that the mutation of K79 to Ala leads to an almost complete loss of activity, suggesting its role in catalytic activity. The inhibition of C. jejuni NapA by cyanide, thiocyanate, and azide has also been investigated. The inhibition studies indicate that cyanide inhibits NapA in a non-competitive manner, while thiocyanate and azide inhibit NapA in an uncompetitive manner. Neither inhibition mechanism involves direct binding of the inhibitor to the Mo-center. These results have been discussed in the context of the loss of catalytic activity of NapA K79A variant and a possible anion binding site in NapA has been proposed. [ABSTRACT FROM AUTHOR]