Nitrogen Fixation In Soybean Research Articles

Correction to: Quantifying country-to-global scale nitrogen fixation for grain legumes. I. Reliance on nitrogen fixation of soybean, groundnut and pulses

Correction to: Quantifying country-to-global scale nitrogen fixation for grain legumes. I. Reliance on nitrogen fixation of soybean, groundnut and pulses

Non-CG DNA hypomethylation promotes photosynthesis and nitrogen fixation in soybean

Non-CG DNA methylation, a plant-specific epigenetic mark mainly regulated by chromomethylase (CMT), is known to play important roles in Arabidopsis thaliana. However, whether and to what extent non-CG DNA methylation modulates agronomic traits in crops remain to be explored. Here, we describe the consequences of non-CG DNA hypomethylation on development, seed composition, and yield in soybean (Glycine max). We created a Gmcmt mutant line lacking function of all four CMT genes. This line exhibited substantial hypomethylation of non-CG (CHG and CHH) sites. Non-CG hypomethylation enhanced chromatin accessibility and promoted or repressed the expression of hundreds of functionally relevant genes, including upregulation of GOLDEN-LIKE 10 (GmGLK10), which led to enhanced photosynthesis and, unexpectedly, improved nitrogen fixation efficiency. The Gmcmt line produced larger seeds with increased protein content. This study provides insights into the mechanisms of non-CG methylation-based epigenetic regulation of soybean development and suggests viable epigenetic strategies for improving soybean yield and nutritional value.

Nitrate Inhibits Nodule Nitrogen Fixation by Accumulating Ureide in Soybean Plants.

The mechanism by which nitrate inhibits nitrogen fixation in soybean (Glycine max L.) is not fully understood. Accumulation of ureide in soybean plant tissues may regulate the nitrogen fixation capacity through a feedback pathway. In this study, unilaterally nodulated dual-root soybeans prepared by grafting were grown in sand culture. They were subjected to the removal of the nodulated side roots, and were given either nitrate supply or no supply to the non-nodulated side roots for 3 days (experiment I). Additionally, they received nitrate supply to the non-nodulated side roots for 1-14 days (experiment II). The results showed that nitrate supply increased the levels of asparagine and ureide in soybean shoots (Experiment I). In Experiment II, nodule dry weight, nodule number, nodule nitrogenase activity, and nodule urate oxidase activity decreased significantly after 3, 7, and 14 days of nitrate supply. Ureide content in the shoots and nodules increased after 1, 3, and 7 days of nitrate supply, but decreased after 14 days of nitrate supply. There was a significant positive correlation between urate oxidase activity and nitrogenase activity. Hence, we deduced that nitrate supply increased the asparagine content in soybean shoots, likely inhibiting ureide degradation, which induced the accumulation of ureide in soybean shoots and nodules, and, in turn, feedback inhibited the nodule nitrogen fixation. In addition, urate oxidase activity can be used to assess the nitrogen fixation capacity of nodules.

Isolation and Identification of Salinity-Tolerant Rhizobia and Nodulation Phenotype Analysis in Different Soybean Germplasms.

Increasing the soybean-planting area and increasing the soybean yield per unit area are two effective solutions to improve the overall soybean yield. Northeast China has a large saline soil area, and if soybeans could be grown there with the help of isolated saline-tolerant rhizobia, the soybean cultivation area in China could be effectively expanded. In this study, soybeans were planted in soils at different latitudes in China, and four strains of rhizobia were isolated and identified from the soybean nodules. According to the latitudes of the soil-sampling sites from high to low, the four isolated strains were identified as HLNEAU1, HLNEAU2, HLNEAU3, and HLNEAU4. In this study, the isolated strains were identified for their resistances, and their acid and saline tolerances and nitrogen fixation capacities were preliminarily identified. Ten representative soybean germplasm resources in Northeast China were inoculated with these four strains, and the compatibilities of these four rhizobium strains with the soybean germplasm resources were analyzed. All four isolates were able to establish different extents of compatibility with 10 soybean resources. Hefeng 50 had good compatibility with the four isolated strains, while Suinong 14 showed the best compatibility with HLNEAU2. The isolated rhizobacteria could successfully establish symbiosis with the soybeans, but host specificity was also present. This study was a preliminary exploration of the use of salinity-tolerant rhizobacteria to help the soybean nitrogen fixation in saline soils in order to increase the soybean acreage, and it provides a valuable theoretical basis for the application of saline-tolerant rhizobia.

Effect of nickel seed treatment in soybeans

Micronutrients such as molybdenum (Mo), cobalt (Co), and nickel (Ni) have been shown to be necessary for maximizing the benefits of biological nitrogen fixation (BNF) in soybeans by mediating enzymatic processes of transforming gaseous nitrogen into mineral nitrogen. The objective of this literature review was to present a research based on a bibliographic review on the influence of nickel application on soybean seeds and its impact on increasing the productivity of this important legume in Brazilian agribusiness. A better understanding of the biochemical processes involved in biological nitrogen fixation in soybeans allowed the recognition of the relevance of nutrients such as Co, Mo, and Ni, especially in the constitution of enzymes such as urease and hydrogenase involved in this important symbiotic relationship between microorganisms and plants. As for nickel, a safe recommended dose for soybean seed treatment with this micronutrient has not yet been established, and relatively few studies have been conducted under Brazilian conditions. When nickel was applied to soybean seeds under various cultivation conditions, positive results were observed (greater nodulation, nodule weight, and enzymatic activity), higher nitrogen content in the plant and protein in the seeds, and higher productivity. Further research involving variables that directly affect nickel availability for soybeans, either through seed treatment or foliar application, still needs to be conducted before recommended dosages can be established.

Identification of loci associated with water use efficiency and symbiotic nitrogen fixation in soybean.

Soybean (Glycine max) production is greatly affected by persistent and/or intermittent droughts in rainfed soybean-growing regions worldwide. Symbiotic N2 fixation (SNF) in soybean can also be significantly hampered even under moderate drought stress. The objective of this study was to identify genomic regions associated with shoot carbon isotope ratio (δ13C) as a surrogate measure for water use efficiency (WUE), nitrogen isotope ratio (δ15N) to assess relative SNF, N concentration ([N]), and carbon/nitrogen ratio (C/N). Genome-wide association mapping was performed with 105 genotypes and approximately 4 million single-nucleotide polymorphism markers derived from whole-genome resequencing information. A total of 11, 21, 22, and 22 genomic loci associated with δ13C, δ15N, [N], and C/N, respectively, were identified in two environments. Nine of these 76 loci were stable across environments, as they were detected in both environments. In addition to the 62 novel loci identified, 14 loci aligned with previously reported quantitative trait loci for different C and N traits related to drought, WUE, and N2 fixation in soybean. A total of 58 Glyma gene models encoding for different genes related to the four traits were identified in the vicinity of the genomic loci.

Biological nitrogen fixation in soybean with different levels of drought tolerance

Biological nitrogen fixation in soybean with different levels of drought tolerance

Phosphorus and Potassium Cycling, Biological Nitrogen Fixation in Soybean, and Soil Microbial Activity in an Oxisol Fertilized with Wastewater from Heparin Production

Phosphorus and Potassium Cycling, Biological Nitrogen Fixation in Soybean, and Soil Microbial Activity in an Oxisol Fertilized with Wastewater from Heparin Production

Mixed Enterobacter and Klebsiella bacteria enhance soybean biological nitrogen fixation ability when combined with rhizobia inoculation

Biological nitrogen fixation is a key process for nitrogen geochemical cycling and plant‒microbe interactions. At present, little is known about the possible effects of nonnodulating microbes on rhizobia nodulation in soils. Here, we show that Enterobacter sp. Z1 and Klebsiella sp. Z2 significantly improved soybean growth and nitrogen fixation in the presence of Bradyrhizobium diazoefficiens USDA110. Soil metabolomic analysis showed that the application of mixed strains Z1 and Z2 significantly increased the levels of flavonoids, indoleacetic acid (IAA), salicylic acid (SA), and taurine in rhizosphere soil. The addition of IAA, SA, or taurine increased nitrogenase activity, nodule production, and chlorophyll content in soybean. Flavonoids were the determinant of the interaction between soybeans and rhizobia. Moreover, strains Z1 and Z2 produced an abundance of IAA and SA, thus increasing the expression of flavonoid synthesis-related genes and eventually increasing the accumulation of flavonoids. Both strains Z1 and Z2 exhibited two metabolic pathways of taurine, and they catalyzed taurine to produce acetyl-CoA, a key flavonoid synthesis substrate in soybeans. This study revealed the mechanism by which rhizosphere microorganisms mediated soybean-rhizobium interactions, thus promoting soybean nitrogen fixation.

A Review on Mitigation of Greenhouse Gases by Agronomic Practices towards Sustainable Agriculture

Agriculture is one among the sources of greenhouse gas emission in the World. Agriculture, being a prominent source of economic sectors in developing countries its impact on environmental climate changes both directly and indirectly through emission of greenhouse gases. To achieve reduced GHGs emissions in agriculture sector, there is a need to adopt climate smart activities and improved food and nutritional security to ensure a climate-smart sustainable agriculture. This short article explores the key ways to mitigate green house gases emissions in agriculture and critically highlights the potential for bacterial nitrogen fixation in soybean which is a recent approach. Symbiotic nitrogen fixation shows a great potential for GHGs mitigation while supporting the agriculture simultaneously. Other agronomic practices include tillage, residue management, rice field management, climate smart agriculture, organic farming and bio energy etc. This will help the farmers and other stakeholders to bring an environmentally friendly agriculture towards more ecological farming approach for future sustainability.

A high-resolution transcriptomic atlas depicting nitrogen fixation and nodule development in soybean.

Although root nodules are essential for biological nitrogen fixation in legumes, the cell types and molecular regulatory mechanisms contributing to nodule development and nitrogen fixation in determinate nodule legumes, such as soybean (Glycine max), remain incompletely understood. Here, we generated a single-nucleus resolution transcriptomic atlas of soybean roots and nodules at 14 days post inoculation (dpi) and annotated 17 major cell types, including six that are specific to nodules. We identified the specific cell types responsible for each step in the ureides synthesis pathway, which enables spatial compartmentalization of biochemical reactions during soybean nitrogen fixation. By utilizing RNA velocity analysis, we reconstructed the differentiation dynamics of soybean nodules, which differs from those of indeterminate nodules in Medicago truncatula. Moreover, we identified several putative regulators of soybean nodulation and two of these genes, GmbHLH93 and GmSCL1, were as-yet uncharacterized in soybean. Overexpression of each gene in soybean hairy root systems validated their respective roles in nodulation. Notably, enrichment for cytokinin-related genes in soybean nodules led to identification of the cytokinin receptor, GmCRE1, as a prominent component of the nodulation pathway. GmCRE1 knockout in soybean resulted in a striking nodule phenotype with decreased nitrogen fixation zone and depletion of leghemoglobins, accompanied by downregulation of nodule-specific gene expression, as well as almost complete abrogation of biological nitrogen fixation. In summary, this study provides a comprehensive perspective of the cellular landscape during soybean nodulation, shedding light on the underlying metabolic and developmental mechanisms of soybean nodule formation.

Biochar application increases biological nitrogen fixation in soybean with improved soil properties in an Ultisol

Biochar application increases biological nitrogen fixation in soybean with improved soil properties in an Ultisol

Soybean Seed Enrichment with Cobalt and Molybdenum as an Alternative to Conventional Seed Treatment

Biological nitrogen fixation in soybean is enhanced when seed is treated with cobalt (Co) and molybdenum (Mo) prior to planting. In this study, our objective was to verify if Co and Mo application during the reproductive phase of the crop increases seed Co and Mo concentration without adverse effects on seed quality. Two experiments were conducted. First, we investigated foliar and soil Co and Mo application under greenhouse conditions. Next, we validated the results obtained in the first study. The treatments for both experiments consisted of Co doses combined with Mo, and a control without Co and Mo application. The foliar application was more efficient in producing enriched Co and Mo seed; meanwhile, as Co doses increased so did Co and Mo concentrations in the seed. There were no adverse effects on nutrition, development, quality, and yield of parent plants and seed when these micronutrients were applied. The seed showed higher germination, vigor, and uniformity for the development of soybean seedlings. We concluded that the application of 20 g ha-1 Co and 800 g ha-1 Mo via foliar application at the reproductive stage of soybean increased germination rate and achieved the best growth and vigor index of enriched seed.

Effects of Co-Inoculating Saccharomyces spp. with Bradyrhizobium japonicum on Atmospheric Nitrogen Fixation in Soybeans (Glycine max (L.)).

Crop production encounters challenges due to the dearth of nitrogen (N) and phosphorus (P), while excessive chemical fertilizer use causes environmental hazards. The use of N-fixing microbes and P-solubilizing microbes (PSMs) can be a sustainable strategy to overcome these problems. Here, we conducted a greenhouse pot experiment following a completely randomized blocked design to elucidate the influence of co-inoculating N-fixing bacteria (Bradyrhizobium japonicum) and PSMs (Saccharomyces cerevisiae and Saccharomyces exiguus) on atmospheric N2-fixation, growth, and yield. The results indicate a significant influence of interaction on Indole-3-acetic acid production, P solubilization, seedling germination, and growth. It was also found that atmospheric N2-fixation, nodule number per plant, nodule dry weight, straw, and root dry weight per plant at different growth stages were significantly increased under dual inoculation treatments relative to single inoculation or no inoculation treatment. Increased seed yield and N and P accumulation were also noticed under co-inoculation treatments. Soil available N was highest under sole bacterial inoculation and lowest under the control treatment, while soil available P was highest under co-inoculation treatments and lowest under the control treatment. We demonstrated that the co-inoculation of N-fixing bacteria and PSMs enhances P bioavailability and atmospheric N2-fixation in soybeans leading to improved soil fertility, raising crop yields, and promoting sustainable agriculture.

White-rot fungus Ceriporia lacerata HG2011 improved the biological nitrogen fixation of soybean and the underlying mechanisms

White-rot fungus Ceriporia lacerata HG2011 improved the biological nitrogen fixation of soybean and the underlying mechanisms

Biochar and biofertilizer reduced nitrogen input and increased soybean yield in the maize soybean relay strip intercropping system

Applying Biochar (BC) or biofertilizers (BF) are potential approaches to reduce the nitrogen input and mitigate soil degradation in the maize soybean relay strip intercropping system (IS). In 2019 and 2020, a two-factor experiment was carried out to examine the effects of BC and BF on soil productivity and yield production in IS. 4 N input levels (8.4, 22.5, 45 kg, and 67.5 kg ha − 1) referred to as N0, N1, N2, and N3 were paired with various organic treatments, including BC (150 kg ha − 1), BF (300 kg ha − 1), and without organic amendments (CK). The results demonstrated that, despite BF decreasing the biomass and N distribution into grains, BF performed better on improved soybean yield (5.2–8.5%) by increasing the accumulation of soybean biomass (7.2 ~ 11.6%) and N (7.7%). Even though BC and BF have a detrimental effect on soybean nitrogen fixation by reducing nodule number and weight, the values of soybean nitrogenase activity and nitrogen fixation potential in BF were higher than those in BC. Additionally, BF performs better at boosting the soil’s nitrogen content and nitrate reductase and urease activity. BF increased the concentration of total N, soil organic matter, Olsen-phosphorus, and alkaline hydrolyzable N in the soil by 13.0, 17.1, 22.0, and 7.4%, respectively, compared to CK. Above all, applying BF combination with N2 (45 kg ha − 1 N) is a feasible strategy to raise crop grain output and keep soil productivity over the long term in IS.

The effect of drought stress on nodulation, plant growth, and nitrogen fixation in soybean during early plant growth

AbstractSoybean [Glycine max (L.) Merr.] is one of the most important grain legume crops in the world. Soybean forms a symbiotic relationship with the nitrogen‐fixing rhizobia bacteria that reside in root nodules and fix atmospheric nitrogen. Most of the soybean's nitrogen demand is derived from symbiotic nitrogen fixation (SNF). Drought is becoming a major threat to crop production in the world. Legumes are sensitive to drought stress, and drought can negatively affect SNF, grain yield, and seed protein production. The effect of drought stress on soybean growth, morphological traits, nodulation, water use efficiency, and SNF, particularly during early plant growth, remains poorly characterized. We hypothesized that early‐onset drought stress can negatively affect nodulation, plant growth, and SNF in soybean during the vegetative growth stages. To test this hypothesis, a controlled‐environment study was conducted using soybean plants grown in pots, where plants were subjected to moderate drought stress (40% field capacity) and well‐watered (80% field capacity) from seeding until the flowering stage. Drought stress significantly reduced the nodule number and nodule dry weight, root and shoot biomass, shoot total nitrogen content, shoot carbon to nitrogen ratio, and shoot total fixed nitrogen compared to the well‐watered control. Conversely, root‐to‐shoot ratio and shoot nitrogen concentration were higher under drought stress compared to well‐watered conditions. These findings enhance our understanding of adverse impacts of drought in the early growth stage of soybean while suggesting that reduced total nitrogen assimilation during the vegetative phase can lead to less nitrogen reserves available for translocating at the seed filling stages for seed protein production. This information should aid in generating drought‐tolerant soybean cultivars.

The Effect of Cultivation Conditions on the Nitrogen Fixation and Seed Yield of Three Ukrainian Varieties of Soybean

The relevance of the research topic is determined by the search for new technological methods of growing soybeans. Therefore, the specifics of the formation of productivity of different varieties of soybeans were investigated depending on a number of factors, such as: dates, methods of sowing and the rate of sowing. The purpose of the research was theoretical substantiation and practical advises of sowing dates and methods, sowing rates of different varieties of soybeans. Indicators of the influence of light intensity, fertilizer application, changes in seed sowing rates and different variants of soybean sowing distance on biological nitrogen fixation of soybeans were analyzed. As a result, regularities were established and a scientific substantiation of provisions was carried out, recommendations for production and scientifically based methods of soybean cultivation technology were developed, which ensure an increase in crop productivity by 15-25%. The developed practical recommendations for increasing soybean production are used in the farms of the region and beyond to solve an important problem − increasing the production of fodder and food protein and vegetable oil. Changing the sowing rate from 0.5 to 0.8 M seeds/ha for row sowing contributed to an increase in the attachment height of the lower beans, which, in turn, contributes to a reduction in crop losses during crop harvesting. Sowing rate had a greater influence on soybean yield than the sowing method. The best conditions were obtained when sowing 0.7 M seeds/ha of similar seeds. During the research, the Romantyka variety showed the highest yield of 3.07 t/ha under the row method of sowing, the sowing rate of 0.8 M seeds/ha and the second sowing period

Characterization of chromosome segment substitution lines reveals candidate genes associated with the nodule number in soybean

Soybean is one of the most important food crops worldwide. Like other legumes, soybean can form symbiotic relationships with Rhizobium species. Nitrogen fixation of soybean via its symbiosis with Rhizobium is pivotal for sustainable agriculture. Type III effectors (T3Es) are essential regulators of the establishment of the symbiosis, and nodule number is a feature of nitrogen-affected nodulation. However, genes encoding T3Es at quantitative trait loci (QTLs) related to nodulation have rarely been identified. Chromosome segment substitution lines (CSSLs) have a common genetic background but only a few loci with heterogeneous genetic information; thus, they are suitable materials for identifying candidate genes at a target locus. In this study, a CSSL population was used to identify the QTLs related to nodule number in soybean. Single nucleotide polymorphism (SNP) markers and candidate genes within the QTLs interval were detected, and it was determined which genes showed differential expression between isolines. Four candidate genes (GmCDPK28, GmNAC1, GmbHLH, and GmERF5) linked to the SNPs were identified as being related to nodule traits and pivotal processes and pathways involved in symbiosis establishment. A candidate gene (GmERF5) encoding a transcription factor that may interact directly with the T3E NopAA was identified. The confirmed CSSLs with important segments and candidate genes identified in this study are valuable resources for further studies on the genetic network and T3Es involved in the signaling pathway that is essential for symbiosis establishment.

Effects of reduced nitrogen application on soil aeration and root nodule growth of relay strip intercropping soybean

<p id="C3">To study the effects of planting system and nitrogen application rate on soybean soil aeration environment and nodulation and nitrogen fixation, we adopted a two-factor split area experiment design, with the main area of planting pattern [soybean monoculture (SS), maize/soybean relay strip intercropping (MS)], and the sub-regions of different nitrogen application rates [no nitrogen application (NN: 0 kg hm^-2), reduced nitrogen application (RN: 45 kg hm^-2), and constant nitrogen application (CN: 60 kg hm^-2)]. The dynamic changes of soil O₂ content and soil respiration rate during soybean growth period was monitored, the differences of soil water-stable aggregates, bulk density, and porosity of each treatment were analyzed, and the variation characteristics of nodulation amount and nitrogen fixation capacity during soybean growth period were discussed. Two years’ data showed that, compared with monoculture soybean, relay strip intercropping soybeans increased soil O₂ content, the percentage of aggregates with a particle size &gt; 2 mm, significantly increased soil porosity and soil respiration rate during the late growth period in soybean; reduced the percentage of aggregates with a particle size of &lt; 1 mm and soil porosity. There was no significant difference in the dry weight of nodules at R5 stage, but the number of nodules was significantly increased by 39.9%. Nitrogenase activity and nitrogen fixation potential were also significantly higher than those of monocrops. Among the various nitrogen application rates, the soil O₂ content, the percentage content of 0.25-1.00 mm particle size, and the soil respiration rate of relay strip intercropping soybean were the highest in RN treatment. Nitrogen application decreased the percentage content of water-stable aggregates with particle size &lt; 0.25 mm and soil bulk density; nitrogen application significantly inhibited the nodulation amount, nitrogenase activity and nitrogen fixation potential of monoculture soybean in the early stage, but the inhibitory effect of nitrogen fertilizer was alleviated at R5 stage. Reduced nitrogen application increased nodulation at the late stage of relay strip intercropping soybean, and it could significantly enhance the nitrogenase activity and nitrogen fixation potential of soybeans during the growth period. Relay strip intercropping soybean combined with reduced nitrogen application promoted the formation of large aggregates, increased soil porosity, improved soybean soil aeration environment, maintained higher soil O₂ content, promoted soil respiration, and facilitated the nodulation and nitrogen fixation of soybean at later stages.