Search

N2 fixation in low‐latitude surface waters dominates the input of fixed nitrogen (N) to the global ocean, sustaining ocean fertility. In the Caribbean Sea, higher foraminifera‐bound (FB‐)δ15N indicates a decline in N2 fixation during ice ages, but its cause and broader implications are unclear. Here, we report three additional Atlantic FB‐δ15N records, from the subtropical North and South Atlantic gyres (MSM58‐50 and DSDP Site 516) and the equatorial Atlantic (ODP Site 662). Similar glacial and interglacial δ15N in the equatorial Atlantic suggests a stable δ15N for the nitrate below the gyre thermoclines. The North Atlantic record shows a FB‐δ15N rise during the ice ages, resembling a previously published FB‐δ15N record from the South China Sea. The commonality among the FB‐δ15N records is that they resemble sea level‐driven variation in regional shelf area, with high FB‐δ15N (inferred reduction in N2 fixation) during periods of low shelf area. The South China Sea shows the largest δ15N signal, the subtropical North Atlantic shows less, and the South Atlantic shows the least, the same ordering as the ice age reductions in continental shelf area in the different regions. Reduced shelf sedimentary denitrification would have increased the nitrogen‐to‐phosphorus ratio of the nutrient supply to open ocean surface waters, leading to decreased N2 fixation and thus higher gyre thermocline nitrate δ15N, explaining the higher FB‐δ15N of peak ice ages. These observations identify shelf sediment denitrification as an important regional driver of modern N2 fixation and imply strong basin‐scale coupling of fixed nitrogen losses and inputs. Plain Language Summary: Nitrogen fixation plays the crucial role in the ocean of supplying bioavailable nitrogen (N), a major nutrient for phytoplankton growth. Variations in nitrogen fixation over time can, therefore, significantly impact ocean productivity and, consequently, carbon sequestration in the ocean interior. To infer past changes in nitrogen fixation during ice ages, we measured the nitrogen isotope (15N‐to‐14N) ratio of organic matter preserved within the carbonate skeleton of planktic foraminifera. Our study reveals a substantial reduction in nitrogen fixation during ice ages in the low‐nutrient regions of the North Atlantic, with only minor variations in the South Atlantic. The basin‐dependent changes are attributed to sea level‐driven reductions in regional continental shelf area during ice ages, resulting in diminished sedimentary denitrification and subsequently lower phosphorus excess in the surface waters downstream of the continental shelves. Overall, our study highlights the importance of regional factors, like shelf sediment denitrification, in influencing oceanic nitrogen fixation within a given ocean basin. Furthermore, it suggests that changes in nitrogen fixation cannot explain the decline in atmospheric carbon dioxide concentration during ice ages. Key Points: Reduction of nitrogen fixation in the Atlantic Ocean during ice ages, proportional to sea‐level variations in regional shelf areaRegional coupling between nitrogen fixation and shelf sedimentary denitrification in the subtropical gyresChange in nitrogen fixation cannot explain the lowering of atmospheric CO2 during ice ages [ABSTRACT FROM AUTHOR]

The life strategies of bacterial communities determine their structure and function and are an important driver of biogeochemical cycling. However, the variations in these strategies under different soil resource conditions remain largely unknown. We explored the bacterial life strategies and changes in structure and functions between Antarctic soils and forest (temperate, subtropical, and tropical) soils. The results showed that the weighted mean rRNA operon copy number in temperate soils was 19.5% lower than that in Antarctic soils, whereas no significant differences were observed among Antarctic, subtropical, and tropical soils. An unexpected result was that bacterial communities in Antarctic soils tended to be copiotrophs, such as Actinobacteriota and Bacteroidota, whereas those in temperate soils tended to be oligotrophs, such as Acidobacteriota and Chloroflexi. Functional predictions showed that in comparison to copiotrophs in Antarctic soils, temperate-inhabiting oligotrophic bacteria exhibited an 84.2–91.1% lower abundance of labile C decomposition genes (hemicellulose, cellulose, monosaccharides, and disaccharides), whereas a 74.4% higher abundance of stable C decomposition (lignin). Genes involved in N cycling (nitrogen fixation, assimilatory nitrate reduction, and denitrification) were 24.3–64.4% lower in temperate soils than in Antarctic soils. Collectively, our study provides a framework for describing the life strategies of soil bacteria, which are crucial to global biogeochemical cycles. [ABSTRACT FROM AUTHOR]

Copyright of Functional Ecology is the property of Wiley-Blackwell 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.)

Ammonia, with its high hydrogen storage density of 17.7 wt.% (mass fraction), cleanliness, efficiency, and renewability, presents itself as a promising zero-carbon fuel. However, the traditional Haber–Bosch (H–B) process for ammonia synthesis necessitates high temperature and pressure, resulting in over 420 million tons of carbon dioxide emissions annually, and relies on fossil fuel consumption. In contrast, dielectric barrier discharge (DBD) plasma-assisted ammonia synthesis operates at low temperatures and atmospheric pressures, utilizing nitrogen and hydrogen radicals excited by energetic electrons, offering a potential alternative to the H-B process. This method can be effectively coupled with renewable energy sources (such as solar and wind) for environmentally friendly, distributed, and efficient ammonia production. This review delves into a comprehensive analysis of the low-temperature DBD plasma-assisted ammonia synthesis technology at atmospheric pressure, covering the reaction pathway, mechanism, and catalyst system involved in plasma nitrogen fixation. Drawing from current research, it evaluates the economic feasibility of the DBD plasmaassisted ammonia synthesis technology, analyzes existing dilemmas and challenges, and provides insights and recommendations for the future of nonthermal plasma ammonia processes. [ABSTRACT FROM AUTHOR]

In modern agricultural systems, high crop yields depend on the high input of orthophosphate-based fertilizers. Owing to the looming scarcity of rock phosphate in the near future, utilization of arbuscular mycorrhizal (AM) symbiosis for the efficient uptake of phosphorus is a necessary approach to maintain crop yield. Plant responsiveness to AM fungi is assessed based on the difference in biomass between plants with and without AM fungal inoculation. Soybean is a plant which establishes both mycorrhizal and rhizobial symbiosis. Therefore, it is difficult to eliminate the symbiotic effects of rhizobial nitrogen fixation during long-term cultivation until soybean harvest. In this study, Bradyrhizobium diazoefficiens USDA110 was inoculated at the same time as soybean seeds were sown, and soybean was grown under Rhizophagus irregularis inoculated and non-inoculated conditions to verify whether the mycorrhizal inoculation effect was observed at the yield level. In 2013, two soybean cultivars Tachinagaha and Williams 82, were grown at five levels of phosphate availability (0, 5, 10, 20, and 40 kg P 10a−1) in an open greenhouse in Tsukuba, Japan. Among the several growth indices analyzed, seed weight per plant was selected as a reliable indicator of plant response. Mycorrhizal inoculation showed a positive effect on soybean under 20 kg P 10a−1 phosphorus fertilization for Williams 82, while Tachinagaha showed almost no effect. This trend was replicated in 2014 and 2016, indicating that Tachinagaha has a lower AM responsiveness than Williams 82. [ABSTRACT FROM AUTHOR]

Composts produced with kiwifruit waste from the calibration process (KW), mixed with 5%, 10%, and 20% wheat straw (WS), were evaluated as crop fertilizers through a pot experiment with lettuce, arranged as a randomized block design. Highest lettuce yields were achieved with 20 and 40 t·ha−1 5%WS compost and 40 t·ha−1 10%WS compost, suggesting that the physical characteristics of the composts increased soil water holding capacity and root growth, whereas chemical characteristics such as pH, organic matter, and nutrient contents contributed to improving soil reaction and nutrient availability. The type of soil amendment used influenced the development of different bacterial consortia in the bulk soil and rhizosphere, leading to increased levels of potentially beneficial bacteria and enhanced levels of relevant functions for plant growth, such as nitrogen fixation. Composted KW as an organic amendment can be used to improve soil quality and the circular economy. [ABSTRACT FROM AUTHOR]

Bambara groundnut is an underutilized food outside the main regions of its consumption. However, after soybean, groundnut, and cowpea, this legume is considered the fourth most significant one. It is an excellent food crop due to various beneficial characteristics, including stress tolerance, nitrogen fixation, and the capacity to grow and sustain in low-input environments. The fact that Bambara groundnut can be eaten untreated demonstrates that it has fewer and least harmful anti-nutritional factors. Due to its well-balanced macronutrient content, this nutrient-dense legume is commonly known as a "complete food". Compared to other legume crops, Bambara groundnut has an excellent nutrition profile for traditional and new food applications, besides the agronomic potential to be planted in many areas globally. Increasing awareness among consumers of Bambara groundnut as a food is needed for this potential crop. This review showed that Bambara groundnut possesses high values of nutritional composition, lower quantity of anti-nutritional properties, and good functional and physico-chemical properties. Discussion on applications of Bambara groundnut in the food industry showed Bambara groundnut could be explored as an alternative source of protein, supplementation of carbohydrate-based foods, and ingredient in many food applications. [ABSTRACT FROM AUTHOR]

Copyright of Rare Metals is the property of Springer Nature 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.)

Biological and abiotic stresses in plant growth are associated with reduced crop yields. Therefore, improving plant stress resistance can be a crucial strategy to improve crop production. To overcome these problems, plant growth-promoting bacteria are emphasized as one of the alternative tools for sustainable agriculture. This study found a novel strain (L3T) of a plant growth-promoting bacterium in fermented Liriope platyphylla fruit. Strain L3T showed the ability to promote plant growth. The L3T strain promoted plant growth of D. carota subsp. sativus, increasing the length (increase rate compared to the control group, 36.98%), diameter (47.06%), and weight of carrots (81.5%), ultimately increasing the edible area. In addition, we confirmed that plant growth was improved even in situations that inhibited plant growth, such as salinity and drought stress. Strain L3T performed indole production, siderophore production, phosphate solubilization, and nitrogen fixation, all characteristics of a strain that promotes plant growth. Genome analysis revealed genes involved in the growth promotion effects of strain L3T. Additionally, the properties of exopolysaccharides were identified and characterized using FTIR, TGA, and UHPLC. Our results demonstrated that L3 isolated from fermented L. platyphylla fruit can be used to simultaneously alleviate drought and NaCl stress. [ABSTRACT FROM AUTHOR]

The implementation of renewable energy sources to electrify ammonia (NH3) production is identified as a critical approach for achieving successful decarburization in the pursuit of a more sustainable future. A liquid metal‐based method is presented for synthesizing bismuth (Bi) nano‐electrocatalysts, enabling efficient and sustainable ammonia production via nitrate electroreduction. Bi‐metal precipitated from a gallium liquid metal alloy yields solution‐processable Bi and oxide with controllable nanostructures such as nanosheets, nanotubes, and nanoparticles. Combining Bi nano‐electrocatalysts and graphene liquid crystals creates self‐assembling layered electrocatalytic systems. Integrating 3D printing technology allows for precise control over the geometry, microporosity, and number of deposited layers of the electrocatalytic scaffold electrode, resulting in improved mass transport properties, durability, and the prevention of catalyst detachment. Consequently, the ammonia production rate reaches 400 nmol s−1 cm−2, with a Faradaic efficiency of over 90% and current densities exceeding 350 mA cm−2. These numbers indicate the excellent scalability potential of the proposed electrocatalytic system. [ABSTRACT FROM AUTHOR]

The sustainable development of novel photo/electrocatalytic CO2/N2 fixation for chemical synthesis is predicated on reliable, accurate, and rapid detection methods. The directness, specificity, and simultaneity in detecting multiple molecules of the 1H nuclear magnetic resonance (1H‐NMR) technique have aroused increasing interest in photo/electrocatalysis. Thus far, two data processing means have been developed for the precise 1H‐NMR data processing: peak integral and peak height methods. However, few detailed studies offer a clear steer for choosing data processing methods for the concerned products in photo/electrocatalysis, especially the guidelines under the conditions of baseline distortions induced by water suppression. Herein, the feasible practices are restudied to quantify classical products in photo/electrocatalytic CO2/N2 fixation. On the basis of experimental results, 1H‐NMR data processing methods (peak integral and peak height methods) are found to convey different applicability for the different low‐concentration products, while introducing water suppression in the 1H‐NMR tests. The essential reason can be attributed to the baseline distortions caused by the water suppression, which arouses differentiated deviation of peaks with different peak widths. With this in mind, an accessible quantification criterion is provided to avoid superfluous input of time or cost in precise 1H‐NMR detection of low‐concentration products. [ABSTRACT FROM AUTHOR]

The conversion of atmospheric nitrogen (N2) into ammonia (NH3), known as nitrogen fixation, plays a crucial role in sustaining life on Earth, facing innovation with electrocatalytic and photocatalytic methods. These approaches promise gentler conversions from atmospheric nitrogen to ammonia, diverging from the energy‐intensive Haber‐Bosch process, which requires complex plant infrastructure. Vitality lies in eco‐friendly, cost‐effective, and energy‐efficient pathways. The challenge is that electrocatalysts and photocatalysts for nitrogen reduction have shown low Faraday efficiency, hampered by hydrogen evolution. This work delves into recent strides in electro/photo‐catalytic nitrogen fixation/reduction, deciphering mechanisms, catalysts, and prospects. By unveiling the core principles steering these processes, it dissects efficiency drivers. Experimental and theoretical studies, ranging from density functional calculations/simulations to machine learning‐based catalyst screening, mark the path toward highly efficient catalysts, including single/multi‐atom catalysts embedded in 2D materials. The journey explores diverse catalysts, assessing their performance, spotlighting emerging nanomaterials, heterostructures, and co‐catalyst techniques. Perspectives on future directions and potential applications of electro/photo‐catalytic nitrogen fixation/reduction are offered, by emphasizing their role in sustainable nitrogen management and their implications for global agriculture and environmental sustainability. [ABSTRACT FROM AUTHOR]

The exceptional electronic properties and potential applications of black phosphorus (BP) have garnered significant interest in the fields of electrochemical catalysis and energy storage. However, its poor environmental stability severely hampers its practical use. In this study, an innovative strategy is proposed to protect fresh black phosphorene (BPene) against oxidation by adsorbing or weakly bonding aluminum ions (Al3+) onto its surface, while facilitating their self‐removal under operating conditions. By leveraging Al3+‐protected black phosphorene (Al‐BPene) as a catalyst for the electrocatalytic reduction of nitrogen to ammonia (NH3), the effectiveness of this removable Al3+‐protected strategy is demonstrated. Quantitative analysis reveals that Al‐BPene maintains structural and compositional stability for over 7 days under ambient conditions, while the Al3+ can be readily eliminated through self‐desorption or dissolution in the electrolyte. With highly active sites pre‐protected, Al‐BPene exhibits a striking NH3 yield rate of 55.1 µg h−1 mg cat−1 and a Faradaic efficiency (FE) of 66.5% in alkaline media, as exemplified by the representative application example. Moreover, it is found that the prepared Al‐BPene can tolerate a thermal environment, and a higher NH3 yield rate of 75 µg h−1 mg cat−1 at 60 °C is recorded. Undoubtedly, these findings pave the way for broader applications of BPene. [ABSTRACT FROM AUTHOR]

Mediterranean high-mountain lakes are being increasingly affected by strong Saharan dust deposition events. However, the ecological impacts of these severe atmospheric episodes remain largely unknown. We examined the effects of a strong Saharan dust intrusion to the Iberian Peninsula in 2022 on the physicochemical parameters and prokaryotic communities in sediments of nine high-mountain lakes of Sierra Nevada (Spain) located above 2800 m.a.s.l and in different orientations (north vs. south). A previous year (2021), with lower Saharan dust deposition with respect to 2022, was used for interannual comparisons. The strong dust deposition to the high-mountain lakes resulted in a significant increase in sediment nutrient availability which was linked to changes in the composition of prokaryotic communities. Decreases in alpha diversity and changes in beta diversity of prokaryotic communities were mainly observed in lakes located in the south compared to the north orientation likely because the former was more affected by the atmospheric dust deposition episode. Dust intrusion to the high-mountain lakes resulted in significant changes in the relative abundance of specific genera involved in important nutrient cycling processes such as phosphate solubilization, nitrogen fixation, nitrification, and denitrification. Saharan dust deposition also increased predicted microbial functionality in all lakes. Our findings show that severe atmospheric dust inputs to remote high-mountain lakes of Sierra Nevada can have significant biogeochemical and biodiversity consequences through changes in nutrient availability and prokaryotic communities in sediments of these freshwater ecosystems. This information contributes to understanding how Mediterranean high-mountain lakes of Sierra Nevada face strong intrusions of Saharan dust and their ecological consequences. [ABSTRACT FROM AUTHOR]

Background: Paenibacillus polymyxa is a bacterial species of high interest, as suggested by the increased number of publications on its functions in the past years. Accordingly, the number of described strains and sequenced genomes is also on the rise. While functional diversity of P. polymyxa has been suggested before, the available genomic data is now sufficient for robust comparative genomics analyses. Results: Using 157 genomes, we found significant disparities among strains currently affiliated to P. polymyxa. Multiple taxonomic groups were identified with conserved predicted functions putatively impacting their respective ecology. As strains of this species have been reported to exhibit considerable potential in agriculture, medicine, and bioremediation, it is preferable to clarify their taxonomic organization to facilitate reliable and durable approval as active ingredients. Conclusions: Strains currently affiliated to P. polymyxa can be separated into two major species groups with differential potential in nitrogen fixation, plant interaction, secondary metabolism, and antimicrobial resistance, as inferred from genomic data. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal "Chemical Communications" published in 2024. It includes various articles and communications on topics such as heterogeneous catalytic activity, 3D printing of soft active materials, synthesis of substituted a-carbolines, and the structure of caffeine-pyrogallol complex. The journal is published by The Royal Society of Chemistry, a leading chemistry community. The document also mentions approved training courses offered by the society. [Extracted from the article]

Herein, a microporous organic–inorganic hybrid, vanadium phosphonate (VPn) material has been developed. With the combined advantages of the periodic organic–inorganic skeleton, a regular microporous channel with a crystalline pore wall, and good surface area, VPn displays electrocatalytic NRR activity with a selective NH3 yield (11.84 μg h−1 mgcat−1), faradaic efficiency of 26.29% at −0.6 V and high stability up to 15 h. The isotopic labeling experiment also verifies the electrosynthesis of NH3 both qualitatively and quantitatively. The theoretical simulation reveals that the associative distal route serves as the most favourable pathway during the NRR, with the first protonation step of *N2 leading to *NNH as the potential determining step. [ABSTRACT FROM AUTHOR]

The nitrogen (N) cycle is the foundation of the biogeochemistry on Earth and plays a crucial role in global climate stability. It is one of the most important nutrient cycles in high-altitude lakes. The biogeochemistry of nitrogen is almost entirely dependent on redox reactions mediated by microorganisms. However, the nitrogen cycling of microbial communities in the high-altitude saline lakes of the Qinghai-Tibet Plateau (QTP), the world's "third pole" has not been investigated extensively. In this study, we used a metagenomic approach to investigate the microbial communities in four high-altitude pristine saline lakes in the Altun mountain on the QTP. We observed that Proteobacteria, Bacteroidota, and Actinobacteriota were dominant in these lakes. We reconstructed 1,593 bacterial MAGs and 8 archaeal MAGs, 1,060 of which were found to contain nitrogen cycle related genes. Our analysis revealed that nitrite reduction, nitrogen fixation, and assimilatory nitrate reduction processes might be active in the lakes. Denitrification might be a major mechanism driving the potential nitrogen loss, while nitrification might be inactive. A wide variety of microorganisms in the lake, dominated by Proteobacteria, participate together in the nitrogen cycle. The prevalence of the dominant taxon Yoonia in these lakes may be attributed to its well-established nitrogen functions and the coupled proton dynamics. This study is the first to systematically investigate the structure and nitrogen function of the microbial community in the high-altitude pristine saline lakes in the Altun mountain on the QTP. As such, it contributes to a better comprehension of biogeochemistry of high-altitude saline lakes. [ABSTRACT FROM AUTHOR]

Photocatalysis has the advantages of practical, sustainable and environmental protection, so it plays a significant role in energy transformation and environmental utilization. CeO2 has attracted widespread attention for its unique 4 f electrons, rich defect structures, high oxygen storage capacity and great chemical stability. In this paper, we review the structure of CeO2 and the common methods for the preparation of CeO2‐based composites in the first part. In particular, we highlight the co‐precipitation method, template method, and sol‐gel method methods. Then, in the second part, we introduce the application of CeO2‐based composites in photocatalysis, including photocatalytic CO2 reduction, hydrogen production, degradation, selective organic reaction, and photocatalytic nitrogen fixation. In addition, we discuss several modification techniques to improve the photocatalytic performance of CeO2‐based composites, such as elemental doping, defect engineering, constructing heterojunction and morphology regulation. Finally, the challenges faced by CeO2‐based composites are analyzed and their development prospects are prospected. This review provides a systematic summary of the recent advance of CeO2‐based composites in the field of photocatalysis, which can provide useful references for the rational design of efficient CeO2‐based composite photocatalysts for sustainable development. [ABSTRACT FROM AUTHOR]

La Muerte lagoon is an ephemeral endorheic water body located in the Monegros desert, Zaragoza, Spain. Amplicon sequencing of the 16S rRNA gene was performed to analyze the bacterial and archaeal communities in biofilmsediment samples over three years, to understand the dynamic changes in the microbial community. PICRUSt and shotgun metagenomics were used to examine energy production and carbohydrate metabolism pathways. The dominant bacterial phyla were Actinobacteriota, Bacteroidota, Cyanobacteriota, and Pseudomonadota, while Halobacteriota was the predominant archaeal phylum. Despite seasonal environmental fluctuations, the biofilm community remained stable over time, suggesting resilience. The Calvin-Benson cycle was the main carbon fixation pathway, carried out by Cyanobacteria and purple non-sulfur bacteria. Nitrogen fixation by diazotrophs supplied an important nitrogen source. Organic carbon was derived primarily from autotrophs, with little use of allochthonous plant material. The comparison of biofilm-sediment and water column biotopes showed distinct but related prokaryote communities. Biofilm-sediments showed higher taxonomic diversity and different proportions of microbial phyla compared to the water column. This study provides initial insights into the complex microbial life in endorheic lagoons and underscores the importance of protecting these globally threatened habitats. The limited sample size in this study warrants further investigation with a more comprehensive sampling strategy to fully characterize the microbial communities and their functional roles in the different biotopes of La Muerte lagoon. [ABSTRACT FROM AUTHOR]

Legumes perform symbiotic nitrogen fixation through rhizobial bacteroids housed in specialised root nodules. The biochemical process is energy‐intensive and consumes a huge carbon source to generate sufficient reducing power. To maintain the symbiosis, malate is supplied by legume nodules to bacteroids as their major carbon and energy source in return for ammonium ions and nitrogenous compounds. To sustain the carbon supply to bacteroids, nodule cells undergo drastic reorganisation of carbon metabolism. Here, a comprehensive quantitative comparison of the mitochondrial proteomes between root nodules and uninoculated roots was performed using data‐independent acquisition proteomics, revealing the modulations in nodule mitochondrial proteins and pathways in response to carbon reallocation. Corroborated our findings with that from the literature, we believe nodules preferably allocate cytosolic phosphoenolpyruvates towards malate synthesis in lieu of pyruvate synthesis, and nodule mitochondria prefer malate over pyruvate as the primary source of NADH for ATP production. Moreover, the differential regulation of respiratory chain‐associated proteins suggests that nodule mitochondria could enhance the efficiencies of complexes I and IV for ATP synthesis. This study highlighted a quantitative proteomic view of the mitochondrial adaptation in soybean nodules. [ABSTRACT FROM AUTHOR]

Over-dose pesticide application disrupts plant physiological processes and soil biological functions; however, the toxicity mechanisms of pesticides and the effectiveness of mitigation measures are still unclear. Our review shows that over-dose of pesticide can cause plant phytotoxicity by enhancing reactive oxygen species and cellular membrane electrolyte leakage, which subsequently decrease chlorophyll biosynthesis, vegetative growth and yield. However, the optimum use of pesticides (insecticides at 0.21 kg a.i. ha-1; herbicides at 1.44 kg a.i. ha-1 and fungicides at =0.4 kg a.i. ha-1) may not interfere with plant physiological functions, while indirectly improving plant nutrients absorption, translocation and yield. In the soil system, pesticide application decreases microbial population by disrupting the microbial metabolism and cellular protein denaturation. Moreover, pesticide application can restrict (by adsorption, etc.) glucose release from organic matter by decreasing the hydrolysis of extracellular enzymes, thereby reducing the labile C source for microbes and resulting in lower soil organic carbon cycling. The pesticide residue can decrease biological nitrogen fixation and nitrogen mineralization by decreasing diazotrophs and saprophytic bacterial population due to cellular hyperkinesis and misfunctions, respectively. Organo-phosphate pesticides can induce oxidative stress to microbes which can affect phosphorus (P) mineralization, but may also enhance P-solubilizing bacterial activities and P availability. The use of biosurfactants, exogenously induced microbes, and soil amendments (e.g., biochar) can effectively remediate pesticide toxicity through solubilization, microbial catabolism and sorption of pesticides by 70%, 78% and 69%, respectively. However, field application of biosurfactants and optimization of biochar characteristics remain challenging for effective pesticide sorption and remediation. [ABSTRACT FROM AUTHOR]

The electrochemical nitrogen reduction reaction (NRR) is an attractive pathway for producing ammonia under ambient conditions. The development of efficient catalysts for nitrogen fixation in electrochemical NRRs has become increasingly important, but it remains challenging due to the need to address the issues of activity and selectivity. Herein, using density functional theory (DFT), we explore ten kinds of triple transition metal atoms (M3 = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) anchored on the C2N monolayer (M3-C2N) as NRR electrocatalysts. The negative binding energies of M3 clusters on C2N mean that the triple transition metal clusters can be stably anchored on the N6 cavity of the C2N structure. As the first step of the NRR, the adsorption configurations of N2 show that the N2 on M3-C2N catalysts can be stably adsorbed in a side-on mode, except for Zn3-C2N. Moreover, the extended N-N bond length and electronic structure indicate that the N2 molecule has been fully activated on the M3-C2N surface. The results of limiting potential screen out the four M3-C2N catalysts (Co3-C2N, Cr3-C2N, Fe3-C2N, and Ni3-C2N) that have a superior electrochemical NRR performance, and the corresponding values are −0.61 V, −0.67 V, −0.63 V, and −0.66 V, respectively, which are smaller than those on Ru(0001). In addition, the detailed NRR mechanism studied shows that the alternating and enzymatic mechanisms of association pathways on Co3-C2N, Cr3-C2N, Fe3-C2N, and Ni3-C2N are more energetically favorable. In the end, the catalytic selectivity for NRR on M3-C2N is investigated through the performance of a hydrogen evolution reaction (HER) on them. We find that Co3-C2N, Cr3-C2N, Fe3-C2N, and Ni3-C2N catalysts possess a high catalytic activity for NRR and exhibit a strong capability of suppressing the competitive HER. Our findings provide a new strategy for designing NRR catalysts with high catalytic activity and selectivity. [ABSTRACT FROM AUTHOR]

Symbiotic nitrogen (N) fixation (SNF) by legumes and their rhizobial partners is one of the most important sources of bioavailable N to terrestrial ecosystems. While most work on the regulation of SNF has focussed on abiotic drivers such as light, water and soil nutrients, the diversity of rhizobia with which individual legume partners may play an important but under-recognized role in regulating N inputs from SNF. By experimentally manipulating the diversity of rhizobia available to legumes, we demonstrate that rhizobial diversity can increase average SNF rates by more than 90%, and that high rhizobial diversity can induce increased SNF even under conditions of high soil N fertilization. However, the effects of rhizobial diversity, the conditions under which diversity effects were the strongest, and the likely mechanisms driving these diversity effects differed between the two legume species we assessed. These results provide evidence that biodiversity–ecosystem function relationships can occur at the scales of an individual plant and that the effects of rhizobial diversity may be as important as long-established abiotic factors, such as N availability, in driving terrestrial N inputs via SNF. [ABSTRACT FROM AUTHOR]

SUMMARY: Symbiotic nitrogen fixation is an energy‐intensive process, to maintain the balance between growth and nitrogen fixation, high concentrations of nitrate inhibit root nodulation. However, the precise mechanism underlying the nitrate inhibition of nodulation in soybean remains elusive. In this study, CRISPR‐Cas9‐mediated knockout of GmNLP1 and GmNLP4 unveiled a notable nitrate‐tolerant nodulation phenotype. GmNLP1b and GmNLP4a play a significant role in the nitrate‐triggered inhibition of nodulation, as the expression of nitrate‐responsive genes was largely suppressed in Gmnlp1b and Gmnlp4a mutants. Furthermore, we demonstrated that GmNLP1b and GmNLP4a can bind to the promoters of GmNIC1a and GmNIC1b and activate their expression. Manipulations targeting GmNIC1a and GmNIC1b through knockdown or overexpression strategies resulted in either increased or decreased nodule number in response to nitrate. Additionally, transgenic roots that constitutively express GmNIC1a or GmNIC1b rely on both NARK and hydroxyproline O‐arabinosyltransferase RDN1 to prevent the inhibitory effects imposed by nitrate on nodulation. In conclusion, this study highlights the crucial role of the GmNLP1/4‐GmNIC1a/b module in mediating high nitrate‐induced inhibition of nodulation. Significance Statement: This study highlights the crucial role of the GmNLP1/4‐GmNIC1a/b module in mediating high nitrate‐induced inhibition of nodulation. [ABSTRACT FROM AUTHOR]

Defect engineering is an emerging technology for tailoring nanomaterials' characteristics and catalytic performance in various applications. Recently, defect‐engineered nanoparticles have emerged as highly researched materials in catalytic applications because of their exceptional redox reaction capabilities and physicochemical and optical properties. The properties of nanomaterials can be readily adjusted by controlling the nature and concentration of defects within the nanoparticles, avoiding the need for intricate design strategies. This review investigates defect engineering in nanocatalysts, including the design, fabrication, and applications. Initially, the various categories and strategies of nanomaterial defects and their impacts on the nanocatalysts' electronic and surface properties, catalytic activity, selectivity, and stability are summarized. Then, the catalytic processes and their uses, including gas sensing, hydrogen (H2) evolutions, water splitting, reductions of carbon dioxide (CO2) and nitrogen to value‐aided products, pollutant degradation, and biomedical (oncotherapy, antibacterial and wound healing, and biomolecular sensing) applications are discussed. Finally, the limitations in defect engineering and the prospective paths for allowing the logical design and optimization of nanocatalytic materials for long‐term and efficient applications are also examined. This comprehensive review gives unique insights into the current state of defect engineering in nanocatalysts and inspires future research on exploiting shortcomings to improve and customize catalytic performance. [ABSTRACT FROM AUTHOR]

Biological nitrogen fixation in legume plants depends on the diversity of rhizobia present in the soil. Rhizobial strains exhibit specificity towards host plants and vary in their capacity to fix nitrogen. The increasing interest in rhizobia diversity has prompted studies of their phylogenetic relations. Molecular identification of Rhizobium is quite complex, requiring multiple gene markers to be analysed to distinguish strains at the species level or to predict their host plant. In this research, 50 rhizobia isolates were obtained from the root nodules of five different Pisum sativum L. genotypes ("Bagoo", "Respect", "Astronaute", "Lina DS", and "Egle DS"). All genotypes were growing in the same field, where ecological farming practices were applied, and no commercial rhizobia inoculants were used. The influence of rhizobial isolates on pea root nodulation and dry biomass accumulation was determined. 16S rRNA gene, two housekeeping genes recA and atpD, and symbiotic gene nodC were analysed to characterize rhizobia population. The phylogenetic analysis of 16S rRNA gene sequences showed that 46 isolates were linked to Rhizobium leguminosarum; species complex 1 isolate was identified as Rhizobium nepotum, and the remaining 3 isolates belonged to Rahnella spp., Paenarthrobacter spp., and Peribacillus spp. genera. RecA and atpD gene analysis showed that the 46 isolates identified as R. leguminosarum clustered into three genospecies groups (B), (E) and (K). Isolates that had the highest influence on plant dry biomass accumulation clustered into the (B) group. NodC gene phylogenetic analysis clustered 46 R. leguminosarum isolates into 10 groups, and all isolates were assigned to the R. leguminosarum sv. viciae. [ABSTRACT FROM AUTHOR]

Background: The popularity of peas (Pisum sativum L.) and pea-derived products is constantly growing globally and is estimated to continue to do so at an average annual rate of 12%. This is partially stimulated by the increase in the consumption of meat analogues and the popularisation of animal-protein-free diets. Peas are considered a great source of protein and dietary fibre and are not depicted as allergenic, making them a good replacement ingredient for other legumes such as soy. Peas are also considered good for the environment, mainly due to their nitrogen fixation capabilities. Despite the above benefits, sensory quality is still a limiting factor in increasing consumer acceptance of peas and pea-derived products. Results: This review has been conducted in accordance with the Joanna Brings Institute's guidance for systematic literature reviews. The search has been conducted on the descriptive sensory terms for Pisum sativum L., where the objectives of the study were to select, present, and analyse the identified descriptive sensory terms for peas found throughout the academic literature. The reviewers have screened 827 articles, of which 12 were eligible for data extraction. Out of the 12 articles, 205 descriptive sensory terms were identified. Those were divided into five categories: smell/odour (27%), flavour (51%), taste (10%), texture (8%), and visual (4%). These included results from sensory analyses by trained/untrained panels and instrumental analyses of texture and of volatile compounds. Conclusion: The identified descriptive sensory terms for Pisum sativum L. could be used for future descriptive sensory evaluation of peas and other legumes, making the process less time consuming. The full list could be used for the initial sensory panel training and then adapted based on the frequency of the depicted terms that meet the criteria for the developed lexicon. [ABSTRACT FROM AUTHOR]

The insectivorous Northern Pitcher Plant, Sarracenia purpurea, recruits a dynamic biotic community in the rainwater collected by its pitcher-shaped leaves. Insect capture and degradation within the pitcher fluid (phytotelma) has been well documented as a mechanism for supplementing the plant's nitrogen, phosphorous, and micronutrient requirements. Metagenomic studies have shown a diverse microbiome in this phytotelm environment, including taxa that contribute metabolically to prey digestion. In this investigation, we used high-throughput 16S rDNA sequencing and bioinformatics to analyze the S. purpurea phytotelm bacteriome as it changes through the growing season (May–September) in plants from the north-central region of the species' native range. Additionally, we used molecular techniques to detect and quantify bacterial nitrogenase genes (nifH) in all phytotelm samples to explore the hypothesis that diazotrophy is an additional mechanism of supplying biologically available nitrogen to S. purpurea. The results of this study indicate that while prokaryote diversity remains relatively stable in plants at different locations within our region, diversity changes significantly as the growing season progresses. Furthermore, nifH genes were detected at biologically significant concentrations in one hundred percent of samples, suggesting that nitrogen fixation may be an important contributor to the S. purpurea nutrient budget. [ABSTRACT FROM AUTHOR]

Manganese is currently experiencing a great deal of attention in homogeneous catalysis as a sustainable alternative to platinum group metals due to its abundance, affordable price and low toxicity. While homogeneous nitrogen fixation employing well‐defined transition metal complexes has been an important part of coordination chemistry, manganese derivatives have been only sporadically used in this research area. In this contribution, the authors systematically cover manganese organometallic chemistry related to N2 activation spanning almost 60 years, identify apparent pitfalls and outline encouraging perspectives for its future development. [ABSTRACT FROM AUTHOR]

The document is the contents list for an issue of the journal Chemical Communications. It includes highlights, cover images, and a list of articles and authors featured in the issue. The journal is published by The Royal Society of Chemistry and aims to connect the world with the chemical sciences. The articles cover a range of topics including asymmetric synthesis, solid-electrolyte interface layers, metal selenides, and various catalytic applications. [Extracted from the article]

Solution plasma-Co(OH)2 interaction significantly boosts nitrogen fixation and achieves a high concentration of NOx− at 9.42 mmol L−1. This surpasses the nitrogen content requirement of 7.67 mmol L−1 for commercial nutrient solutions, offering a sustainable approach for nitrogen fixation from nitrogen, water and electricity. [ABSTRACT FROM AUTHOR]

Ammonia (NH3) production is of global concern for today's food supply security and as future energy vector. Plasma technology can add to supply‐chain resilience of fertilizer production and improve the environmental profile using renewable energy; allowing distributed NH3 production. With the objective to provide process intensification of small‐capacity reactors for local supply, a novel micropyramid‐disk plasma reactor operated in micro‐arc mode was developed. NH3 was synthesized from N2, nitrogen, and H2, hydrogen over Ru/MCM‐41 catalyst at atmospheric pressure. The microplasma brings plasma and catalyst surface close together and intensifies the electric field. The arc plasma elevates temperature, 'nonthermal', releasing high‐energy free electrons, known to be effective in converting low‐reactive molecules. The study demonstrates that microplasma, with reduced electrode‐to‐electrode dimensions and a microstructured reaction environment, enhances the performance of the NH3 synthesis and opens novel process windows. This is detailed on the impact of feed ratio (N2/H2), applied voltage, frequency, electrode gap, and the flow distribution by which the gas is fed in. Optical emission spectroscopy (OES) was used to identify vibrationally and other excited species generated by the microplasma and confirms the catalyst is in symbiosis with the radicals. [ABSTRACT FROM AUTHOR]

The synthesis of ammonia (NH3) via the Haber–Bosch process is energy-intensive and environmentally challenging, necessitating the development of sustainable alternatives. Herein, we report a directed etch template strategy to create atomically dispersed Ru–N4 active sites within layered porous carbon (NC@Ru) for efficient electrochemical nitrogen reduction reaction (NRR). The removal of the MgO template results in an interconnected carbon network with hierarchical porous structures, significantly enhancing the accessibility and mass transfer of the active sites. The NC@Ru catalyst demonstrated superior NRR performance, achieving an ammonia yield rate of 196.2 μg h–1 mgcat.–1 and a Faradaic efficiency of 43.8%. In situ electrochemical mass spectrometry was employed to analyze NRR kinetics, while density functional theory calculations were utilized to elucidate the NRR mechanism and identify the rate-determining step. The work introduces a novel high-performance catalyst for electrocatalytic NRR and provides a practical strategy for optimizing active-site microenvironments, laying the groundwork for future commercial applications of electrocatalytic NRR. [ABSTRACT FROM AUTHOR]

The response of N2 fixation to projected future conditions in the ocean cannot be reliably predicted to date. We conducted a minicosm experiment with preacclimated cultures of the globally significant diazotroph Crocosphaera watsonii strain WH8501 ("Crocosphaera"). PH and temperature were altered simultaneously to match the RCP scenarios 4.5 and 6 and investigate a more realistic future scenario compared to studies that focus on changes of a single stressor only. The cell abundance and nitrogen metabolism of Crocosphaera was monitored over 5 days. Our results imply that Crocosphaera is able to simultaneously perform N2 fixation and assimilate dissolved inorganic nitrogen (DIN, i.e., nitrate and ammonium) under all the conditions tested and implies a competition with non-diazotrophic phytoplankton for DIN, which should be further investigated. Using NanoSIMS analysis of single cells, our results point towards a preference for DIN assimilation over N2 fixation under more acidic and warmer conditions. Overall, our results show that while the combined alteration of pH and temperature had a negative effect on the diazotroph's growth and N2 fixation, Crocosphaera is likely to cope well with conditions in the future ocean. The high intra-population variability in nitrogen assimilation pathways may give this species the flexibility to quickly react to environmental changes. [ABSTRACT FROM AUTHOR]

Pulse crops, including beans, peas, chickpeas, and lentils, are vital sources of protein, fiber, and essential nutrients worldwide. They serve not only as staple foods but also as key components of sustainable agricultural practices, contributing to soil fertility through nitrogen fixation and enhancing overall productivity. However, pulse crops face numerous abiotic and biotic stresses mainly insect pest attack and pathogen invasion, which pose significant threats to pulse crops, impacting both production and food security. To overcome these challenges, plants have evolved diverse defense mechanisms, including the emission of specific volatile organic compounds (VOCs). These volatiles play crucial roles in plant communication, protection, and real-time health status indication. Monitoring VOCs offers a promising approach for early detection of pest infestations or pathogen infections, enabling the grower to take early action and decide on the proper control measure to minimize losses. The identification of plant-emitted VOCs requires robust and sensitive analytical techniques such as gas chromatography andmass spectrometry, which are themainly used techniques for in pulse crops studies. However, traditional methods have limitations, prompting the need for advanced, portable, and real-time detection alternatives, such as gas-sensing technologies. This paper provides a comprehensive review of VOC measuring methods, including extraction, separation, and analytical techniques, focusing on their application in pulse crops. Recent advancements in gas-sensing technologies are also discussed, highlighting their potential in enhancing crop protection and agricultural sustainability. [ABSTRACT FROM AUTHOR]

Artificial ammonia synthesis via the Haber‐Bosch process is environmentally problematic due to the high energy consumption and corresponding CO2 ${_2 }$ emissions, produced during the reaction and before hand in hydrogen production upon methane steam reforming. Photocatalytic nitrogen fixation as a greener alternative to the conventional Haber‐Bosch process enables us to perform nitrogen reduction reaction (NRR) under mild conditions, harnessing light as the energy source. Herein, we systematically review first‐principles calculations used to determine the electronic/optical properties of photocatalysts, N2 adsorption and to expound possible NRR mechanisms. The most commonly studied photocatalysts for nitrogen fixation are usually modified with dopants, defects, co‐catalysts and Z‐scheme heterojunctions to prevent charge carrier recombination, improve charge separation efficiency and adjust a band gap to for utilizing a broader light spectrum. Most studies at the atomistic level of modeling are grounded upon density functional theory (DFT) calculations, wholly foregoing excitation effects paramount in photocatalysis. Hence, there is a dire need to consider methods beyond DFT to study the excited state properties more accurately. Furthermore, a few studies have been examined, which include higher level kinetics and macroscale simulations. Ultimately, we show there is still ample room for improvement with regard to first principles calculations and their integration in multiscale models. [ABSTRACT FROM AUTHOR]

Main group Bi‐based materials have gained popularity as N2 reduction reaction (NRR) photo/electrocatalysts due to their ability to inhibit competitive H2 evolution reactions (HER) and the unique N2 adsorption activities. The introduction of defects in Bi‐based catalysts represents a highly effective strategy for enhancing light absorption, promoting efficient separation of photogenerated carriers, optimizing the activity of free radicals, regulating electronic structure, and improving catalytic performance. In this review, we outline the various applications of state of the defect engineering in Bi‐based catalysts and elucidate the impact of vacancies on NRR performance. In particular, the types of defects, methods of defects tailoring, advanced characterization techniques, as well as the Bi‐based catalysts with abundant defects and their corresponding catalytic behavior in NRR were elucidated in detail. Finally, the main challenges and opportunities for future development of defective Bi‐based NRR catalysts are discussed, which provides a comprehensive theoretical guidance for this field. [ABSTRACT FROM AUTHOR]

In root nodule symbioses (RNS) between nitrogen (N)‐fixing bacteria and plants, bacterial symbionts cycle between nodule‐inhabiting and soil‐inhabiting niches that exert differential selection pressures on bacterial traits. Little is known about how the resulting evolutionary tension between host plants and symbiotic bacteria structures naturally occurring bacterial assemblages in soils. We used DNA cloning to examine soil‐dwelling assemblages of the actinorhizal symbiont Frankia in sites with long‐term stable assemblages in Alnus incana ssp. tenuifolia nodules. We compared: (1) phylogenetic diversity of Frankia in soil versus nodules, (2) change in Frankia assemblages in soil versus nodules in response to environmental variation: both across succession, and in response to long‐term fertilization with N and phosphorus, and (3) soil assemblages in the presence and absence of host plants. Phylogenetic diversity was much greater in soil‐dwelling than nodule‐dwelling assemblages and fell into two large clades not previously observed. The presence of host plants was associated with enhanced representation of genotypes specific to A. tenuifolia, and decreased representation of genotypes specific to a second Alnus species. The relative proportion of symbiotic sequence groups across a primary chronosequence was similar in both soil and nodule assemblages. Contrary to expectations, both N and P enhanced symbiotic genotypes relative to non‐symbiotic ones. Our results provide a rare set of field observations against which predictions from theoretical and experimental work in the evolutionary ecology of RNS can be compared. [ABSTRACT FROM AUTHOR]

This article explores the role of a protein called VAPYRIN (VPY) in the process of rhizobial infection in legume plants. Rhizobial infection is necessary for legumes to fix nitrogen, and the study focuses on the specific amino acid Asp394 in VPY. The research found that Asp394 is crucial for the interaction between VPY and another protein called LIN, as well as for the localization and function of VPY during infection. The study suggests that Asp394 may play a significant role in the interaction between VPY and other components of the infectosome complex, but further research is needed to fully understand its function in plant-microbe interactions. [Extracted from the article]

The capture and reduction of atmospheric dinitrogen gas to ammonium can be accomplished through the enzyme nitrogenase in a process known as biological nitrogen fixation (BNF), by a class of microbes known as diazotrophs. The diazotroph Azotobacter vinelandii is a model organism for the study of aerobic nitrogen fixation, and in recent years has been promoted as a potential producer of biofertilizers. Prior reports have demonstrated the potential to partially deregulate BNF in A. vinelandii, resulting in accumulation and extracellular release of ammonium. In many cases, deregulation requires the introduction of transgenic genes or elements to yield the desired phenotype, and the long‐term stability of these strains has been reported to be somewhat problematic. In this work, we constructed two strains of A. vinelandii where regulation can be precisely controlled without the addition of any foreign genes or genetic markers. Regulation is maintained through native promoters found in A. vinelandii that can be induced through the addition of extraneous galactose. These strains result in varied degrees of regulation of BNF, and as a result, the release of extracellular ammonium is controlled in a precise, and galactose concentration‐dependent manner. In addition, these strains yield high biomass levels, similar to the wild‐type A. vinelandii strain and are further able to produce high percentages of the bioplastic polyhydroxybutyrate. [ABSTRACT FROM AUTHOR]

The use of man-made nanoparticles (NPs) has increased exponentially in recent years, many of which accumulate in significant quantities in soil, including through use in agriculture as nanofertilizers and nanopesticides. ZnO NPs are more environmentally friendly but have specific antimicrobial activity, which can affect soil microbiota, thereby influencing key microbial processes such as mineralization, nitrogen fixation and plant growth-promoting activities. Their behavior and persistence in soil depend on their chemical nature and soil characteristics. This review summarizes the applications of ZnO NPs in soil systems and their effects on various plants and soil microorganisms, particularly rhizobacteria that promote plant growth. A stimulating effect of ZnO NPs on the morphometric and biochemical characteristics of plants, as well as on soil microbiota and its activity at relatively low concentrations of up to 500 mg/mL and 250 mg/kg, respectively, is observed. As the concentration of ZnO NPs increases above these limits, toxic effects appear. The different effects of ZnO NPs are related to their size, dose, duration of exposure, solubility in water, as well as soil type, acidity and organic matter content. The review substantiates the need to study the behavior of ZnO NPs in the "soil-plant-microbiota" system for the possibility of using nanotechnologies in the agricultural industry and ensuring the safety of agricultural products. [ABSTRACT FROM AUTHOR]

Phosphorus deficiency severely limits crop yields and hinders sustainable agricultural development. Phosphate-solubilizing bacteria (PSB) are beneficial for crop growth because they enhance the uptake and utilization of phosphorus. This study explored the phosphorus-solubilizing, IAA-producing, nitrogen-fixing, potassium-solubilizing, and siderophore-producing abilities of three bacterial strains (Pantoea sp. J-1, Burkholderia cepacia Z-7, and Acinetobacter baumannii B-6) screened from the maize rhizosphere. A pot experiment was also conducted to explore the role of screened PSB in the growth of maize. Finally, the effects of the PSB on the physicochemical properties, enzyme activities, and microbial community structure of maize rhizosphere soil were analyzed. The results showed that strain Z-7 had the strongest abilities phosphorus solubilization, nitrogen fixation, potassium solubilization, and siderophore production, while strain J-1 exhibited the highest yield of IAA. The application of PSB promoted the growth of maize plants to different extents. Among the different treatments, the mixed bacterial treatment (J-1 + Z-7 + B-6) had the most potent growth promotion effect, and the consortium treatment significantly enhanced the activity of soil phosphatase. Soil pH, total phosphorus (TP), total potassium (TK), available phosphorus (AP), NH4+-N, and NO3−-N are key factors for the growth of maize plants. In addition, PSB significantly altered the microbial community structure in the maize rhizosphere soil, and the relative abundance of Proteobacteria increased by 16.07–69.10% compared to the control. These PSB have obvious growth-promoting abilities, with the potential to enhance crop productivity as excellent candidate strains for the development of biological fertilizers. [ABSTRACT FROM AUTHOR]

Streptomyces can produce secondary metabolites with a wide range of activities and is often used in agriculture as a biocontrol strain to control soil-borne diseases. Screening and isolation from infected soil is an effective method to obtain active strains. In this study, the best antagonistic inter-root growth-promoting bacteria were isolated from grapevine inter-root soil samples, and strain F2 was identified as Streptomyces sp. based on morphological, physiological, and biochemical characteristics as well as 16S rDNA sequencing results. The results showed that the fermentation broth/liquid and sterile filtrate of strain F2 exhibited antagonistic effects against 10 plant pathogens, with an inhibition rate reaching up to 80%. Notably, two of them exhibited remarkable inhibitory effects against Phytophthora capsici with inhibition rates of 80.58% and 87.71%, respectively. The P. capsici leaf control experiment revealed that the control effect of strain F2 fermentation liquid on P. capsici filaments was 61.09%. Furthermore, indoor pot experiments demonstrated that the fermentation liquid of strain F2 had a significant inhibitory effect on pepper blight, with a maximum inhibition of 83.31%. Antagonistic factor analysis indicated that strain F2 had specific organophosphorus hydrolysis, nitrogen fixation, extracellular protease secretion, and IAA production capabilities. Additionally, root treatment with strain F2's fermentation liquid significantly enhanced capsicum growth. Taking together, Streptomyces F2 not only exhibits a wide-spectrum antagonistic effect against plant pathogens but also promotes plant growth, which suggests that Streptomyces F2 can be used as an effective biological control resource and provides important theoretical support for the application of Streptomyces F2. [ABSTRACT FROM AUTHOR]

The symbiotic nitrogen fixation between rhizobia and peanuts offers an advantage in reducing nitrogen fertilizer inputs, decreasing the incidence rate of peanuts, and enhancing soil fertility. Inoculating rhizobia agent is an effective pathway to improve both the quality and yield of peanuts, contributing to food security and promoting sustainable agricultural practices. This study conducted a one-year field experiment in a subtropical humid monsoon climate area in Southeast China to investigate the effects of rhizobia agents on the growth and crop yield of four peanut varieties (i.e., Taihua No.4, No.6, No.8, and No.10). Our research showed that inoculation with rhizobia agent can increase the plant height, lateral branch length, fresh root weight, and leaf area of the four peanut varieties. Meanwhile, inoculation with a rhizobia agent can significantly (p < 0.05) increase the ~50% number of root nodules. Especially for the early-maturing and drought-resistant variety, Taihua No.4 exhibited the highest number of nodules and peanut fruits per plant in the pod-setting stage after inoculation with rhizobia agent, i.e., 24.5 and 18.0, respectively. Under the conventional fertilization conditions (N-P2O5-K2O 15-15-15, 450 kg/hm2), Taihua No.4 and No.6 inoculated with rhizobia agent achieved higher yield increase rates of 11.0% and 11.6% compared to other peanut varieties. This study indicated that the Taihua No.4 and No.6 are the most suitable peanut varieties for rhizobia inoculation and promotion, with enormous potential for yield increase. Meanwhile, optimizing rhizobia inoculation techniques and evaluating soil health status, economic benefits of peanuts, and applicable regions should be explored in the future. [ABSTRACT FROM AUTHOR]

Biological nitrogen fixation (BNF) can provide the necessary nitrogen for bean crops; however, for this to occur, important limitations involving the inoculant application technology need to be overcome.The use of co-inoculation is a management technique used to obtain benefits and increase the potential of N2 fixation from the association between bacteria from the rhizobia group, such as R. tropici, and bacteria that promote plant growth, such as A. brasilense, in association with the addition of nutrients that allow greater efficiency of bacteria fixing atmospheric N2. This study aimed to evaluate the bean response to the reinoculation of R. tropici in co-inoculation with A. brasilense in a mixture with the micronutrients Co/Mo, in the winter season of 2021, in Anápolis-GO, Brazil. A randomized block design was used, with four replications, and the following treatments (TRs) were studied: TR1—reinoculation with R. tropici; TR2—reinoculation with co-inoculation of R. tropici + A. brasilense; TR3—reinoculation of R. tropici + Mo/Co micronutrients; TR4—reinoculation with co-inoculation R. tropici + A. brasilense + Mo/Co micronutrients; TR5—inoculation via seed, without reinoculation; TR6—mineral N fertilization in the sowing furrow and topdressing; TR7—control, without any N source. At stage R6, nodulation characteristics (number and dry mass of nodules) and the morphophysiological parameters of the plants (main root length, root dry mass, plant height, shoot dry mass, leaf area, and leaf N content in the shoot) were evaluated. At harvest, the final plant stand and components (number of pods per plant, number of grains per pod, and average weight of one hundred grains) were determined, in addition to grain yield. It was concluded that inoculation followed by reinoculation in topdressing with R. tropici in co-inoculation with A. brasilense plus Mo/Co, compared to mineral nitrogen fertilization, improves the efficiency of the nodulation process and the morphophysiological characteristics of the common bean crop. Seed inoculation and topdressing application with R. tropici, associated with co-inoculation with A. brasilense + Mo and Co, have the potential to completely replace mineral nitrogen fertilization in common bean crops. [ABSTRACT FROM AUTHOR]

The restriction of plant‐symbiont dinitrogen fixation by an insect semiochemical had not been previously described. Here we report on a glycosylated triketide δ‐lactone from Nephrotoma cornicina crane flies, cornicinine, that causes chlorosis in the floating‐fern symbioses from the genus Azolla. Only the glycosylated trans‐A form of chemically synthesized cornicinine was active: 500 nM cornicinine in the growth medium turned all cyanobacterial filaments from Nostoc azollae inside the host leaf‐cavities into akinetes typically secreting CTB‐bacteriocins. Cornicinine further inhibited akinete germination in Azolla sporelings, precluding re‐establishment of the symbiosis during sexual reproduction. It did not impact development of the plant Arabidopsis thaliana or several free‐living cyanobacteria from the genera Anabaena or Nostoc but affected the fern host without cyanobiont. Fern‐host mRNA sequencing from isolated leaf cavities confirmed high NH4‐assimilation and proanthocyanidin biosynthesis in this trichome‐rich tissue. After cornicinine treatment, it revealed activation of Cullin‐RING ubiquitin‐ligase‐pathways, known to mediate metabolite signaling and plant elicitation consistent with the chlorosis phenotype, and increased JA‐oxidase, sulfate transport and exosome formation. The work begins to uncover molecular mechanisms of cyanobiont differentiation in a seed‐free plant symbiosis important for wetland ecology or circular crop‐production today, that once caused massive CO2 draw‐down during the Eocene geological past. Summary Statement: The glycosylated triketide δ‐lactone cornicinine from crane flies elicited and maintained cyanobiont akinete differentiation in mosquito fern symbioses sharing the wetland habitat; it revealed processes of cell‐differentiation in ecologically significant N2‐fixing symbioses with cyanobacteria. [ABSTRACT FROM AUTHOR]

Interactions between arbuscular mycorrhizal (AM) fungi and free‐living nitrogen fixers (FLNF) occur in the rhizosphere where they can enhance plant nutrient acquisition, impact plant growth, and affect soil processes. Tripartite mutualism commonly occurs between nodule‐forming plants, symbiotic diazotrophs, and AM fungi, and can occur between non‐nodulating plants, FLNF, and AM fungi. However, information on the extent of, and controls on, tripartite mutualism in non‐nodulating plant systems is limited to a small number of crop plants and culturable microbial inoculum, mostly in greenhouse growing conditions. We conducted a systematic literature review to synthesize the current understanding of the responses of plants, AM fungi, and FLNF to co‐inoculation, as well as the conditions affecting tripartite mutualism and the magnitude and range of benefits conferred. Our review shows that plants generally benefit from co‐inoculation with AM fungi and FLNF taxa, but benefits are highly variable and context dependent, ranging from 94% reduction in plant shoot biomass to 255% increase in total plant biomass. Additionally, the presence of AM fungi can increase abundance of FLNF and the presence of FLNF can increase AM fungal root colonization, but these responses also vary widely. Major factors influencing variation in response to co‐inoculation by all organisms include plant phenology/age, soil type and nutrient availability, and partner pairing. There is potential for leveraging these tripartite mutualisms to improve plant productivity and soil microbial function, but successful application is more likely with a thorough understanding of the environmental and mechanistic controls on these relationships and testing of field‐scale implementation. Core Ideas: Co‐inoculation with arbuscular mycorrhizal (AM) fungi and free‐living nitrogen fixers (FLNF) most consistently benefits plants by increasing total biomass and yield.Co‐inoculation with FLNF consistently increases AM root colonization in both cereal and non‐cereal plants.FLNF response to co‐inoculation is underreported, but evidence suggests abundance increases in non‐cereal plants.Overall responses to co‐inoculation by all organisms are generally positive, but highly variable.Variability in response to co‐inoculation largely depends on partner pairing, resource availability, and plant age. [ABSTRACT FROM AUTHOR]

Associations between bryophytes and dinitrogen (N2)-fixing bacteria are a significant source of exogenous N in unmanaged boreal and possibly temperate ecosystems. However, the extent to which biological N2-fixation (BNF) applies to the boreal–temperate ecotone remains elusive. The current focus on common species limits our understanding of BNF at the community level. Our objective was to characterize the presence of cyanobacteria and BNF activity associated with bryophytes in the coastal forests of Fundy National Park (New Brunswick, Canada). In 2021, we harvested three liverwort and 11 moss species from two sites (71 samples) and measured environmental covariates (e.g., canopy composition and soil pH). We used stable isotope incubations with 15N2 gas in growth chambers to quantify potential BNF activity and used phycocyanin extractions as a cyanobacteria abundance proxy. Many species presented detectable BNF rates, which were similar to or higher than those of well-studied feather mosses. These included species that have rarely been found to contribute to BNF. While cyanobacteria were present on most samples, we found no positive association between abundance and BNF. Our findings are among the first records for bryophyte-associated BNF in the boreal–temperate ecotone of eastern Canada and offer insights into the potential role of this process in N cycling in coastal conifer-dominated forests. [ABSTRACT FROM AUTHOR]

Aims: Inoculation with climate-adapted rhizobia is able to increase legume productivity in drought-prone regions of Sub-Saharan Africa. Enhanced nodulation might additionally affect plant-soil interactions and control rhizosphere carbon (C) and nitrogen (N) pools. Methods: We investigated inoculation effects on nodulation and biological N2 fixation (BNF) of Vigna unguiculata and consequent effects on C and N pools in two Namibian soils. Three treatments (Bradyrhizobium sp.1–7 inoculant, non-inoculated, N-fertilised with 50 kg N ha−1) were applied in rhizoboxes at 45% and 20% maximum water holding capacity. Nodule development was photo-documented, and rhizobia-DNA sequences were identified. BNF was assessed by δ15N enrichment, and organic C and N pools were analysed in bulk and root adherent soil. Results: Plant growth initially enhanced mineral N losses from the rhizosphere at flowering stage (6 weeks growth), but led to a re-increase of N, and organic C contents after ripening (10 weeks). Inoculation had no effect on nodulation and soil C and N pools, indicating that both soils contained sufficient indigenous rhizobia to allow effective nodulation. However, the inoculant strain was more competitive in establishing itself in the root nodules, depending on the local conditions, showing a need for regional adjustment of inoculation strategies. Conclusion: Water stress was the main limitation for nodulation and, in combination with soil type, substantially affected rhizosphere and bulk soil C and N contents. The temporally enhanced rhizodeposition after ripening could be able to maintain soil C and N pools after legume cultivation. [ABSTRACT FROM AUTHOR]