Common Metal Research Articles

Characterization of the structural and molecular interactions of Ferulic acid ethyl ester with human serum albumin and Lysozyme through multi-methods

Ferulic acid ethyl ester (FAEE) is an essential raw material for the formulation of drugs for cardiovascular and cerebrovascular diseases and leukopenia. It is also used as a fixed aroma agent for food production due to its high pharmacological activity. In this study, the interaction of FAEE with Human serum albumin (HSA) and Lysozyme (LZM) was characterized by multi-spectrum and molecular dynamics simulations at four different temperatures. Additionally, the quenching mechanism of FAEE-HSA and FAEE-LZM were explored. Meanwhile, the binding constants, binding sites, thermodynamic parameters, molecular dynamics, molecular docking binding energy, and the influence of metal ions in the system were evaluated. The results of Synchronous fluorescence spectroscopy, UV–vis spectroscopy, CD, three-dimensional fluorescence spectrum, and resonance light scattering showed that the microenvironment of HSA and LZM and the protein conformation changed in the presence of FAEE. Furthermore, the effects of some common metal ions on the binding constants of FAEE-HSA and FAEE-LZM were investigated. Overall, the experimental results provide a theoretical basis for promoting the application of FAEE in the cosmetics, food, and pharmaceutical industries and significant guidance for food safety, drug design, and development.

Rechargeable Zn-H2O hydrolysis battery for hydrogen storage and production.

Reactive metals hydrolysis offers significant advantages for hydrogen storage and production. However, the regeneration of common reactive metals (e.g., Mg, Al, etc.) is energy-intensive and produces unwanted byproducts such as CO2 and Cl2. Herein, we employ Zn as a reactive mediator that can be easily regenerated by electrolysis of ZnO in an alkaline solution with a Faradaic efficiency of >99.9 %. H2 is produced in the same electrolyte by constructing a Zn-H2O hydrolysis battery consisting of a Zn anode and a Raney-Ni cathode to unlock the Zn-H2O reaction. The entire two-step water splitting reaction with a net energy efficiency of 70.4 % at 80 °C and 50 mA cm-2. Additionally, the Zn-H2O system can be charged using renewable energy to produce H2 on demand and runs for 600 cycles only sacrificing 3.76 % energy efficiency. DFT calculations reveal that the desorption of H* on Raney-Ni (-0.30 eV) is closer to zero compared with that on Zn (-0.87 eV), indicating a faster desorption of H* at low overpotential. Further, a 24 Ah electrolyzer is demonstrated to produce H2 with a net energy efficiency of 65.5 %, which holds promise for its real application.

Rechargeable Zn‐H2O hydrolysis battery for hydrogen storage and production

AbstractReactive metals hydrolysis offers significant advantages for hydrogen storage and production. However, the regeneration of common reactive metals (e.g., Mg, Al, etc.) is energy‐intensive and produces unwanted byproducts such as CO2 and Cl2. Herein, we employ Zn as a reactive mediator that can be easily regenerated by electrolysis of ZnO in an alkaline solution with a Faradaic efficiency of >99.9 %. H2 is produced in the same electrolyte by constructing a Zn‐H2O hydrolysis battery consisting of a Zn anode and a Raney‐Ni cathode to unlock the Zn‐H2O reaction. The entire two‐step water splitting reaction with a net energy efficiency of 70.4 % at 80 °C and 50 mA cm−2. Additionally, the Zn‐H2O system can be charged using renewable energy to produce H2 on demand and runs for 600 cycles only sacrificing 3.76 % energy efficiency. DFT calculations reveal that the desorption of H* on Raney‐Ni (−0.30 eV) is closer to zero compared with that on Zn (−0.87 eV), indicating a faster desorption of H* at low overpotential. Further, a 24 Ah electrolyzer is demonstrated to produce H2 with a net energy efficiency of 65.5 %, which holds promise for its real application.

Spectrally selective radiation infrared stealth based on a simple Mo/Ge bilayer metafilm

In this paper, we propose and demonstrate a spectrally selective radiation infrared stealth metafilm based on a simple bilayer structure. Specifically, we use the common inexpensive metal Mo instead of traditional precious metals and achieve selective thermal radiation in the infrared band. In the atmospheric window band, the absorptivity is relatively low, which can well achieve the purpose of infrared stealth, while in the non-atmospheric window band, the absorptivity acutely increases, with a high absorptivity of 94.89 % at 6.04 μm, which can achieve better radiation heat dissipation. The experimental results are consistent with the simulation. The average emissivity in the 8–14 μm atmospheric window band is 0.32, while in the 5–8 μm non-atmospheric window band is 0.80, which proves the possibility of its practical application. Meanwhile, the metafilm proposed by us can be easily fabricated and can be widely used in the control of infrared thermal radiation, thermal management, and thermal camouflage, which has a very promising application prospect.

Efficient capture of lead ions from aqueous solution by the functional covalent organic framework materials

Lead is one of the most common harmful metals in aqueous solutions. It has become an urgent need to devise a method that can effectively remove Pb(II) from aqueous solutions. In this paper, a novel covalent organic framework adsorbent was synthesized by post-modification method to remove Pb(II) from aqueous solution. This adsorbent analyzed by adsorption isotherms, kinetic and thermodynamic studies shows that the adsorption is chemically monolayer and controlled by intraparticle diffusion. The whole adsorption process is an exothermic and spontaneous reaction process. The maximum adsorption capacity of the adsorbent for Pb(II) can reach 359.94 mg/g at 298 K and the optimum pH 4. The zeta and density functional theory suggest that the electrostatic and coordination interactions between N, O and S functional groups and Pb(II) play a key role in the adsorption process. The selectivity and reproducibility results showed that this adsorbent was capable of targeted removal of Pb(II) from a polyionic environment and maintained a high adsorption efficiency after 5 cycles. In conclusion, this adsorbent has a very good application in the removal of metal ions from aqueous solutions.

CdS/ZnS quantum dots based on an amphipathic polymer platform for fluorescent probe of dopamine with high sensitivity and selectivity

Due to the widespread presence of dopamine in living organisms and its physiological and pharmacological effects, developing rapid and sensitive methods for detecting dopamine has been of great significance. Fluorescent probes are a commonly used and highly sensitive detection method. In this work, based on a self-developed amphipathic polymer template, CdS/ZnS fluorescent quantum dots (QDs) with a maximum absorption wavelength of 500–550 nm were synthesized and characterized. They exhibited stable fluorescence in the pH range from weak acid to alkaline, and fluorescence quenching occurred at pH = 4.5. The QDs could be applied as fluorescent probes for detecting dopamine, with a limit of detection 0.027 mM and high selectivity, unaffected by common metal ions, amino acids, glucose, etc. Compared to the high activity of dopamine being oxidized easily, this fluorescent QDs and its template polymer PEI played a stabilizing role during the testing process. Therefore, this work provides a promising dopamine fluorescent probe with application prospects.

Preparation and properties of gel-type low-temperature phase change materials

In the context of the dual‑carbon target, there is a high emphasis on the energy efficiency of traditional mechanical cold storage systems with significant power consumption. Additionally, the implementation of time-of-use electricity pricing has played a crucial role in driving the rapid advancement of energy storage technology. The application of energy storage technology in cold storage can significantly reduce the energy consumption of the refrigeration system, save operating costs by shifting peak demand to valleys, and reduce start and stop frequencies. Therefore, studying phase-change materials with high latent heat, low cost, and good performance for cold storage is of great practical application in cold storage. The paper developed four types of gel-type phase-change cold storage materials with high latent heat, low cost, and good cycle stability. These materials mainly consist of NH4Cl, KCl, and deionized water. The phase transition temperature ranges from −18 to −21 °C, the latent heat of phase change is approximately 260 to 289 J/g, and the thermal conductivity ranges from 0.58 to 0.60 W/(m·K), which can meet the cooling demand of cold storage facilities. Furthermore, by comparing the phase transition temperature, latent heat value of phase change, and cyclic stability, a gel-type PCM with good comprehensive properties was selected for corrosion and corrosion inhibition studies with five common metal samples in welded and non-welded forms. The results showed that material B2 had slight corrosion on 1060 aluminum, 6061 aluminum, and 304 stainless steels, but no obvious corrosion phenomenon was found on 316 stainless steels. The corrosion rate of the material on red copper was the highest, and the corrosion was too strong. In addition, the corrosion of welded parts is more serious than that of non-welded parts, and the welding points are more susceptible to corrosion. Adding the corrosion inhibitor BTA to material B2 can reduce the corrosion rate of red copper by more than 94 %.

Selective electrocatalytic oxidation of ammonia to nitrogen by using titanium dioxide nanorod array decorated with ultrasmall Ir nanoparticles and non-noble metal Fe nanoparticles

Electrochemical ammonia oxidation process through active chlorine has been proposed as a potentially effective method for ammonia removal. Currently, most of the anodes require to use high-stable TiO2 loaded with large particles of noble metal Ru or Ir, which have low activity and high cost. Herein, we prepare ultrasmall and uniform metal nanoparticles of Ir on TiO2 to remove ammonia. Moreover, we use non-noble metal Fe to replace noble metals. The ammonia removal efficiency of Fe/TiO2 under 2 VVS Ag / AgCl during 2 h is 100 % and 94 % of ammonia is converted to N2. The Fe/TiO2 anodes not only have higher catalytic activity but also show excellent stability and reusability. Fe/TiO2 anodes still exhibit excellence activity and selectivity after 1 year. As a common metal, Fe will have more application space than iridium in ammonia removal for its low cost and selectively high efficiency.

Designing the bimetallic catalysts by the adsorption strength of metal atoms for efficient oxygen reduction: A density functional theory study

In this paper, a new design principle for bimetallic catalysts is proposed by combining strongly adsorbed atoms (SAA) with weakly adsorbed atoms (WAA) where the SAA and WAA are classified by the free adsorption energy of oxygen-containing intermediates on the metal atom. And the ORR performances of the bimetallic catalysts designed by the method are compared with the common single metal atom catalysts. The method is successfully confirmed as the overpotential of the Mn-based bimetallic catalysts decreases from 0.63 V in G-MnN4 to as low as 0.33 V, and that of the Fe-based bimetallic catalysts decreases from 0.76 V in G-FeN4 to 0.23 V. In addition, the correlation between adsorption free energy and adsorption bond length is revealed for the first time, and the optimal adsorption bond length is determined. Finally, the adsorption energy of O2 is plotted versus the free adsorption energy of three oxygen-containing intermediates for the first time, and a suitable adsorption energy of O2 is found to be -1.4∼-1.0 eV. These findings provide a new perspective for the design of high-performance bimetallic catalysts.

Polydimethylsiloxane (PDMS)-assisted non-destructive transient thermoreflectance characterizations.

The conventional pump-probe thermoreflectance (pump-probe TR) techniques are routinely performed on a thin (typically <100nm) metal transducer deposited on samples, ensuring the most fundamental principle of thermoreflectance: the reflectance change (∆R/R) of the sample surface is directly and linearly related to the temperature change (∆T) within a finite temperature range. However, general metal coating methods may damage the sample by forming a mixed layer with the sample. In this article, we present a non-destructive pump-probe transient thermoreflectance (TTR) characterization using the polydimethylsiloxane (PDMS)-assisted metal transfer technique. Our method utilizes PDMS dry transfer to transfer common transducer metals (Au and Al) to the target substrate. This method effectively avoids impurities and damage to the sample. In particular, we have utilized Au as a transition layer to study the application of Al transfer in TTR measurements. The substrate thermal conductivity measurement results show that they can all be used for TTR measurement, and the thermal boundary conductance results show that the transferred metals have low bonding to the substrate. In addition, Al/Au can be transferred over a large area at room temperature compared to Au. After measurement, the samples can be restored to their original state by a simple cleaning method. This method provides a simple and reliable way to characterize samples without metal coating for TTR.

Physical and chemical properties of aluminum tailings mud modified by metal ions

Aluminum tailings mud, a type of waste generated by bauxite washing during alumina production, is harmful. Owing to the isomorphism substitution of iron-aluminum symbiotic minerals, a large number of metal ions inevitably exist in the slurry, which causes the suspension to maintain dispersion and hinders the drainage of aluminum tailings mud. This study examined the effects of the pH and commonly associated metal ions, such as K+ and Fe3+, on the sedimentation characteristics of aluminum tailings mud. Zeta potential analyzer, X-ray fluorescence spectrum analysis, and electron scanning microscopy were used to study the effects of common metal ions in the tailings slurry on the sedimentation characteristics of aluminum tailings mud. The results showed that the sedimentation effect of the tailings slurry was superior after adding Fe3+ compared with K+. The mechanism analysis shows that at a certain pH range, the addition of metal ions can compress the thickness of the electric double layer on the surface. The high-valence ions (Fe3+) will have more electric double layer compression than monovalent ions (Na+), which is more conducive to the agglomeration of aluminum tailing mud particles. This conclusion provides guidance for efficient drainage of aluminum tailings mud.

The effect of heavy metals (Cd, Cu, and Pb) on plant growth parameters and the phytoremediation capacity of corn

Heavy metal contamination is currently a major global environmental issue. Heavy metals contaminate the soils where crops and vegetables grow. Maize (Zea mays L.) is widely employed for phytoremediation because of its high biomass output and metal accumulation capacity. Depending on the plant and soil properties, some metals can be dangerous in high amounts. During our in vitro experiment, different levels of Cd, Cu, and Pb were introduced to a growth medium to allow maize plants to develop under diverse conditions. The study examined numerous growth features under certain metal stress conditions, including seed germination, plant height, biomass, and chlorophyll content, as well as the toxicity symptoms and mechanisms of the most common heavy metals. The study revealed that, while the maize plant is a good heavy metal accumulator, high heavy metal concentrations had a negative impact on several growth indicators: at 250 ppm, Cd inhibited captive seed germination by 50% and wild seed germination by 42.9%; Pb suppressed captive seed germination by 57% and wild seed germination by 42.9%; and Cu inhibited germination in both seed types by 40%. Similarly, plant height decreased in the following order: Pb (36.2%), Cd (24.8%), and Cu (9.7%) for the captive seed plant, and Pb (46.7%), Cd (28%), and Cu (13%) for the wild seed plant. Keywords: MAIZE, STRESS, TOXICITY, HEAVY METAL, POLLUTION, PHYTOREMEDIATION, BIOACCUMULATION

Влияние тяжелых металлов (Cd, Cu и Pb) на параметры роста растений и фиторемедиационную способность кукурузы

Heavy metal contamination is currently a major global environmental issue. Heavy metals contaminate the soils where crops and vegetables grow. Maize (Zea mays L.) is widely employed for phytoremediation because of its high biomass output and metal accumulation capacity. Depending on the plant and soil properties, some metals can be dangerous in high amounts. During our in vitro experiment, different levels of Cd, Cu, and Pb were introduced to a growth medium to allow maize plants to develop under diverse conditions. The study examined numerous growth features under certain metal stress conditions, including seed germination, plant height, biomass, and chlorophyll content, as well as the toxicity symptoms and mechanisms of the most common heavy metals. The study revealed that, while the maize plant is a good heavy metal accumulator, high heavy metal concentrations had a negative impact on several growth indicators: at 250 ppm, Cd inhibited captive seed germination by 50% and wild seed germination by 42.9%; Pb suppressed captive seed germination by 57% and wild seed germination by 42.9%; and Cu inhibited germination in both seed types by 40%. Similarly, plant height decreased in the following order: Pb (36.2%), Cd (24.8%), and Cu (9.7%) for the captive seed plant, and Pb (46.7%), Cd (28%), and Cu (13%) for the wild seed plant. Keywords: MAIZE, STRESS, TOXICITY, HEAVY METAL, POLLUTION, PHYTOREMEDIATION, BIOACCUMULATION

Protective effects of gallic acid against nickel-induced kidney injury: impact of antioxidants and transcription factor on the incidence of nephrotoxicity

Nickel (Ni) is a common metal with a nephrotoxic effect, damaging the kidneys. This study investigated the mechanism by which gallic acid (GA) protects mice kidneys against renal damage induced by Nickel oxide nanoparticles (NiO-NPs). Forty male Swiss albino mice were randomly assigned into four groups, each consisting of ten mice (n = 10/group): Group I the control group, received no treatment; Group II, the GA group, was administrated GA at a dosage of 110 mg/kg/day body weight; Group III, the NiO-NPs group, received injection of NiO-NPs at a concentration of 20 mg/kg body weight for 10 consecutive days; Group IV, the GA + NiO-NPs group, underwent treatment with both GA and NiO-NPs. The results showed a significant increase in serum biochemical markers and a reduction in antioxidant activities. Moreover, levels of 8-hydroxy-2’-deoxyguanosine (8-OH-dG), phosphorylated nuclear factor kappa B (p65), and protein carbonyl (PC) were significantly elevated in group III compared with group I. Furthermore, the western blot analysis revealed significant high NF-κB p65 expression, immunohistochemistry of the NF-κB and caspase-1 expression levels were significantly increased in group III compared to group I. Additionally, the histopathological inspection of the kidney in group III exhibited a substantial increase in extensive necrosis features compared with group I. In contrast, the concomitant coadministration of GA and NiO-NPs in group IV showed significant biochemical, antioxidant activities, immunohistochemical and histopathological improvements compared with group III. Gallic acid has a protective role against kidney dysfunction and renal damage in Ni-nanoparticle toxicity.

Biomass hydrothermal carbonization solution-assisted synthesis of intercalation-expanded core–shell structured molybdenum disulfide for efficient adsorption of Cr (VI) in electroplating wastewater treatment

Cr (VI) is a common heavy metal pollutant in electroplating wastewater. This study introduces the liquid-phase product from the hydrothermal reaction of coffee grounds (CGHCL) into the synthesis process of molybdenum disulfide, assisting in the fabrication of an intercalated, expanded core–shell structured molybdenum disulfide adsorbent (C-MoS2), designed for the adsorption and reduction of Cr (VI) from electroplating wastewater. The addition of CGHCL significantly enhances the adsorption performance of MoS2. Furthermore, C-MoS2 exhibits exceedingly high removal efficiency and excellent regenerative capability for Cr (VI)-containing electroplating wastewater. The core–shell structure effectively minimizes molybdenum leaching to the greatest extent, while the oleophobic interface is unaffected by oily substances in water, and the expanded interlayer structure ensures the long-term stability of C-MoS2 in air (90 days). This study provides a viable pathway for the resource utilization of biomass and the application of molybdenum disulfide-based materials in wastewater treatment.

Essential and toxic elements analysis of wild boar tissues from north-eastern Romania and health risk implications

IntroductionThe level of essential minerals in meat is an important factor in human nutrition and health. Meat from responsibly managed wildlife is an alternative raw material with considerable nutritional benefits. Meat from hunted animals has essential and non-essential elements for the human body. It is important to carefully monitor the levels of heavy metals accumulated in the tissues of hunted animals in polluted areas to ensure food safety and environmental contamination. High levels of heavy metals in food and the environment can pose a danger to human health.MethodsThe study aims to investigate the levels of essential mineral elements and heavy metals in the muscle tissue and organs of wild boar harvested through the herd density control plan over the last decade in north-eastern Romania.Results and discussionThe statistical analysis indicates that the age of the animals had a significant impact on Fe, Cu, and Zn levels in Longissimus lumborum. In the kidney a highly significant difference in Fe content by sex, with males showing higher values than females. The sex was shown to significantly influence the Mg levels. However, there are concerns about the accumulation of heavy metals such as Lead (Pb) and Cadmium (Cd), which may hurt the health of game meat consumers in the study area. Cd level it shows significant differences according to both age and sex, with higher concentrations in adults and males. Statistical analysis shows a negative correlation between Fe and Zn concentrations in muscle samples, while a positive correlation was found between Fe and Mn in kidney samples. There was also a positive association between Zn and Cu in muscle samples, but a negative association in kidney samples. Principal component analysis shows significant variation in essential element and heavy metals data between muscle and kidney samples. The loading plot shows a direct correlation between Pb and Cu and between Pb and Cd. However, an opposite correlation also is observed between Cu and Mg, Cd and Mg, and Pb and Mg. HQ (Hazard Quotient) for children compared to adults indicates a potentially higher risk associated with meat consumption among children because children are more vulnerable than adults. We report for the first time, to the best authors’ knowledge, various levels of essential minerals and exceeded maximum admitted level of heavy metals in the muscle tissues and kidneys of Sus scrofa ferus from Romania intended for human consumption, moreover, our findings highlight the need for strict monitoring and implementation of appropriate corrective measures, given the significant percentages of muscle and kidney samples exceeding the allowable limits for two of the most common toxic metals in the environment.

Acridinedione-based fluorescence ‘turn-off’ sensor for real-time detection of carcinogenic Cr (VI) ions

This research introduces AR-1, a newly developed chemosensor tailored for Cr (VI) ion detection in semi-aqueous solutions. AR-1 demonstrates notable alterations in coloration and reduced fluorescence output upon interaction with Cr (VI) ions, showing remarkable selectivity even amidst other interfering metal ions. Fluorescence spectral titrations were employed to ascertain the binding constant and detection thresholds of the AR-1-Cr (VI) complex, with LOD and LOQ established at 0.639 µM and 0.021 μM, respectively. Further characterization via 1H NMR titrations, DFT calculations, Job’s plot, and HRMS analysis provided insights into the detection mechanism. The probe proved dependable within a pH range of 3.0 to 11.0, displaying resilience against interference from common metal ions. Overall, AR-1 presents a direct and efficient means for Cr (VI) ion detection in environmental samples, offering a promising alternative to traditional detection methods.

Effect of the type of ion-exchange resin on Mn&lt;sup&gt;2+&lt;/sup&gt; adsorption in the presence of competing cations

Present in soils, ground and surface waters, manganese is among the most common metals in Earth crust. It is also an essential trace element to the functioning of several enzymes in the human body. However, exposure to high manganese concentrations can also be harmful to humans with psychiatric and motor effects and therefore, manganese concentrations in drinking water and also industrial effluents are regulated. In the current work, the adsorption of Ca&lt;sup&gt;2+&lt;/sup&gt;, Mg&lt;sup&gt;2+&lt;/sup&gt; and Mn&lt;sup&gt;2+&lt;/sup&gt; on three different ion-exchange resins: (i) aminophosphonic acid - chelating (Purolite S950), (ii) polyacrylic weak acid cation (Purolite C104E) and (iii) polystyrene strong acid cation (Purolite C100) was investigated. The results revealed that Purolite S950 had the highest Mn2+ uptake (37.9 mg/mL-resin or 0.69 mmol/mL-resin) as compared to Ca&lt;sup&gt;2+&lt;/sup&gt; (3.2 mg/mL-resin or 0.08 mmol/mL-resin) and Mg&lt;sup&gt;2+&lt;/sup&gt; (~0 mg/mL-resin) and was selected for further kinetics and equilibrium studies. The results indicated Purolite S950 as particularly suited to be applied in the treatment of neutral mine waters with high Mg/Mn ratios. Additionally, Purolite S950 showed a small affinity for Ca&lt;sup&gt;2+&lt;/sup&gt; and therefore an efficient Mn&lt;sup&gt;2+&lt;/sup&gt; removal will depend on the Ca/Mn ratio of the mine water under treatment. According to the kinetic analysis, manganese sorption on Purolite S950 was described by the pseudo-second order model (r&lt;sup&gt;2&lt;/sup&gt; &gt; 0.98) with an activation energy of 10.40 kJ/mol and thus pore-difussion was the rate controlling step of the process. In terms of equilibrium studies, manganese sorption on Purolite S950 followed the Langmuir model with maximum loadings of up to 41.5 mg/mL-resin. The thermodynamic modelling indicated an exothermic process (-85.0 kJ/mol, as standard enthalpy) with a standard entropy of -274 J/mol.K, which was ascribed to the release of two adsorbed H&lt;sup&gt;+&lt;/sup&gt; ions for each Mn&lt;sup&gt;2+&lt;/sup&gt; ion taken up from solution

Genome-wide identification and expression pattern analysis of the Aux/IAA (auxin/indole-3-acetic acid) gene family in alfalfa (Medicago sativa) and the potential functions under drought stress

BackgroundAuxin/induced-3-acetic acid (Aux/IAA) is an important plant hormone that affects plant growth and resistance to abiotic stresses. Drought stress is a vital factor in reducing plant biomass yield and production quality. Alfalfa (Medicago sativa L.) is the most widely planted leguminous forage and one of the most economically valuable crops in the world. Aux/IAA is one of the early responsive gene families of auxin, playing a crucial role in response to drought stress. However, the characteristics of the Aux/IAA gene family in alfalfa and its potential function in response to drought stress are still unknown.ResultA total of 41 Aux/IAA gene members were identified in alfalfa genome. The physicochemical, peptide structure, secondary and tertiary structure analysis of proteins encoded by these genes revealed functional diversity of the MsIAA gene. A phylogenetic analysis classified the MsIAA genes into I-X classes in two subgroups. And according to the gene domain structure, these genes were classified into typical MsIAA and atypical MsIAA. Gene structure analysis showed that the MsIAA genes contained 1–4 related motifs, and except for the third chromosome without MsIAAs, they were all located on 7 chromosomes. The gene duplication analysis revealed that segmental duplication and tandem duplication greatly affected the amplification of the MsIAA genes. Analysis of the Ka/Ks ratio of duplicated MsAux/IAA genes suggested purification selection pressure was high and functional differences were limited. In addition, identification and classification of promoter cis-elements elucidated that MsIAA genes contained numerous elements associated to phytohormone response and abiotic stress response. The prediction protein–protein interaction network showed that there was a complex interaction between the MsAux/IAA genes. Gene expression profiles were tissue-specific, and MsAux/IAA had a broad response to both common abiotic stress (ABA, salt, drought and cold) and heavy metal stress (Al and Pb). Furthermore, the expression patterns analysis of 41 Aux/IAA genes by the quantitative reverse transcription polymerase chain reaction (qRT-PCR) showed that Aux/IAA genes can act as positive or negative factors to regulate the drought resistance in alfalfa.ConclusionThis study provides useful information for the alfalfa auxin signaling gene families and candidate evidence for further investigation on the role of Aux/IAA under drought stress. Future studies could further elucidate the functional mechanism of the MsIAA genes response to drought stress.

Rhizobium symbiosis improves amino acid and secondary metabolite biosynthesis of tungsten-stressed soybean (Glycine max).

The industrially important transition metal tungsten (W) shares certain chemical properties with the essential plant micronutrient molybdenum and inhibits the activity of molybdoenzymes such as nitrate reductase, impacting plant growth. Furthermore, tungsten appears to interfere with metabolic processes on a much wider scale and to trigger common heavy metal stress response mechanisms. We have previously found evidence that the tungsten stress response of soybeans (Glycine max) grown with symbiotically associated N2-fixing rhizobia (Bradyrhizobium japonicum) differs from that observed in nitrogen-fertilized soy plants. This study aimed to investigate how association with symbiotic rhizobia affects the primary and secondary metabolite profiles of tungsten-stressed soybean and whether changes in metabolite composition enhance the plant's resilience to tungsten. This comprehensive metabolomic and proteomic study presents further evidence that the tungsten-stress response of soybean plants is shaped by associated rhizobia. Symbiotically grown plants (N fix) were able to significantly increase the synthesis of an array of protective compounds such as phenols, polyamines, gluconic acid, and amino acids such as proline. This resulted in a higher antioxidant capacity, reduced root-to-shoot translocation of tungsten, and, potentially, also enhanced resilience of N fix plants compared to non-symbiotic counterparts (N fed). Taken together, our study revealed a symbiosis-specific metabolic readjustment in tungsten-stressed soybean plants and contributed to a deeper understanding of the mechanisms involved in the rhizobium-induced systemic resistance in response to heavy metals.