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In soybean production, numerous strategies are utilized to enhance seed quality and mitigate the effects of biotic and abiotic stressors. Zn-based nutrient priming has been shown to be effective for field crops, and biopriming is a strategy that is becoming increasingly important for sustainable agriculture. On the other hand, there is a lack of information about the effect of comprehensive nutrient priming and biopriming techniques on soybean seed quality and viability and seed health. This study was performed to assess the benefits of nutrient priming with Zn, biopriming with Bacillus megaterium and Bradyrhizobium japonicum (single and co-inoculation), and combination of nutrient priming and biopriming on the seed quality and viability, as well as seed infection caused by Alternaria spp. and Fusarium spp. Three different laboratory tests were employed: germination test, accelerated aging test, and seed health test. The results revealed that all tested priming treatments have a beneficial effect on seed germination, initial plant growth, and reduction of seed infection in normal and aged seeds. Additionally, comprehensive priming with Zn, Bacillus megaterium, and Bradyrhizobium japonicum reduced the occurrence of Alternaria spp. (−84% and −75%) and Fusarium spp. (−91% and −88%) on soybean seeds in the germination and accelerated aging tests, respectively, as compared to the control, which proved to be the most effective treatment in both optimal and stressful conditions. [ABSTRACT FROM AUTHOR]

Soybean is a dual-purpose crop, as it serves as pulse and fodder. Legumes like soybeans have a distinctive characteristic of nodule formation. Nitrogen fixation enhancement can succeed by inoculation of soybeans with specific strains of rhizobia, ensuring adequate levels of healthy bacteria near the seed. The presented study materialized during 2018–2020 at the University of Agriculture, Faisalabad, and Ayub Agricultural Research Institute, Faisalabad, Pakistan. Two strains of Bradyrhizobium japonicum—S377 and S379—were treatments for inoculating 80 soybean accessions collected from the National Agriculture Research Center, Islamabad. Sowing 10 inoculated seeds per genotype and two seeds for control continued in a randomized complete block design (RCBD). Fresh root and shoot weights, dried root and shoot weights, nodule dry weight, grain and biomass yield, protein, and oil content increased significantly after inoculating seeds with rhizobial strains. These traits also showed significant genotypic correlations. The protein content, followed by the fresh shoot weight, directly affected nodule formation, increasing nitrogen fixation. [ABSTRACT FROM AUTHOR]

Soybean [Glycine max (L.) Merr.] is one of the most important and oldest crops. Due to its ability to form symbiotic interactions with nitrogen-fixing bacteria, it is a valuable source of nitrogen for agriculture and proteins for humans and livestock. In Europe, for instance, in Poland, the soybean cultivation area is still not large but is gradually increasing due to climate change. The lack of indigenous soybean microsymbionts in Polish soils forces the application of commercial strains to establish effective symbioses. Fast and reliable identification methods are needed to study the persistence, competitiveness, and dispersal of bradyrhizobia introduced as inocula. Our study aimed to apply real-time PCR coupled with high-resolution melting curve (HRM) analysis to detect and differentiate bacterial strains occupying soybean nodules. HRM-PCR was performed on crude extracts from nodules using primers specific for recA, a highly conserved nonsymbiotic gene. By comparing them with the reference strains, we were able to identify and assign Bradyrhiobium strains that had been introduced into field locations in Poland. In conclusion, HRM analysis was proven to be a fast and accurate method for identifying soybean microsymbionts and might be successfully used for identifying other legume-nodulating bacteria. [ABSTRACT FROM AUTHOR]

Background. Numerous scientific and industrial studies have proven the high effectiveness of using micronutrients in nanoscale form in agricultural crop cultivation technologies. Among them, special attention is drawn to soybeans, which hold a leading position in terms of sown areas among other leguminous crops in the country. They can provide up to 70 % of their own nitrogen needs through the fixation of its molecular form from the atmosphere in symbiosis with Bradyrhizobium japonicum nodulating bacteria. New methods of molecular biology, biotechnology, and genetic engineering, along with classical methods of microbiology, plant physiology, genetics, and agrochemistry, allow for addressing both fundamental questions regarding the characteristics of formation and functioning of legume-rhizobial systems, and practical approaches to correcting the interactions between symbiotic partners with the aim of creating highly effective symbioses. Therefore, research aimed at significant increasing the current level of biological nitrogen fixation and adapting symbiotic systems to negative environmental factors is currently relevant. The use of nanotechnology, in particular, the study of the effect of iron, germanium, and cobalt nanocarboxylates on the formation and functioning of the soybean-rhizobial symbiosis under field conditions in combination with seed inoculation with rhizobial bacteria may be promising. Materials and Methods. The objects of the investigation were symbiotic systems created with the participation of the Almaz variety of soybean and the Bradyrhizobium japonicum B1-20 rhizobacteria, and with the introduction of nanocarboxylates of iron (Fe), germanium (Ge) and cobalt (Co) into their cultivation medium. Physiological, microbiological, biochemical, and statistical research methods were used. Results. It was found that under field conditions, before the pod formation stage, the vegetative mass of soybean plants inoculated with rhizobial bacteria with the introduction of nanoparticles of carboxylates of iron, germanium, or cobalt into their cultivation medium was at the level of control plants or slightly exceeded them. It has been shown that under the effects of chelated micronutrients, the number of root nodules increased compared to control plants during the flowering and pod formation stages, and their mass was greater from the three trifoliate leaf stage, which ensured efficient functioning of the legume-rhizobial symbiosis. It has been noted that the used metal nanocarboxylates promote active functioning of the symbiotic apparatus in soybean plants, as an increase in nitrogen-fixing activity was observed at the stages of three trifoliate leaf development and flowering, ranging from 26–70 % depending on the microelement used. Conclusions. During field cultivation of soybeans, the effectiveness of pre-sowing seed inoculation with Bradyrhizobium japonicum B1-20 rhizobia was demonstrated through the introduction of iron, germanium, or cobalt nanocarboxylates into their cultivation medium. This opens up opportunities for increasing the efficiency of symbiotic systems of soybeans.

Bradyrhizobium japonicum bacteria on the intensity of nodulation during nine phenophases (R1-R7) in relation to the isoflavone content in soybean seeds. Nine domestic soybean varieties were sown in three replicates, with Bradyrhizobium japonicum inoculated and non-inoculated seeds. The different morphological characteristics of nodules, the number and mass of nodules were studied during plants' ontogenesis. The content of individual isoflavones in the sowing seed material was determined using high performance liquid chromatography mass spectrometry (HPLC-MS). The most abundant isoflavone was acetylgenistin in the variety Galeb (2741.4 µg/g), and the highest content of all isoflavones was recorded in the variety Gorštak (8117.7 µg/g). The variety Sava of the inoculated treatment exhibited the highest average values of the nodule mass (21.1 mg) and the highest number of nodules (23.3) in the phenophase, in which 10% of pods reached full length (R4). The average values of mass and number of nodules were calculated for the entire vegetation period, being higher in the inoculated treatment. There was no positive correlation between the content of isoflavones in seeds and the number and mass of nodules. The impact of quantity of isoflavone on nodulation intensity in soybeans was not significant, which could be related to already saturated soil with nitrogen-fixing bacteria. [ABSTRACT FROM AUTHOR]

Bradyrhizobium japonicum bacteria on the intensity of nodulation during nine phenophases (R1-R7) in relation to the isoflavone content in soybean seeds. Nine domestic soybean varieties were sown in three replicates, with Bradyrhizobium japonicum inoculated and non-inoculated seeds. The different morphological characteristics of nodules, the number and mass of nodules were studied during plants’ ontogenesis. The content of individual isoflavones in the sowing seed material was determined using high performance liquid chromatography mass spectrometry (HPLC-MS). The most abundant isoflavone was acetylgenistin in the variety Galeb (2741.4 μg/g), and the highest content of all isoflavones was recorded in the variety Gorštak (8117.7 μg/g). The variety Sava of the inoculated treatment exhibited the highest average values of the nodule mass (21.1 mg) and the highest number of nodules (23.3) in the phenophase, in which 10% of pods reached full length (R4). The average values of mass and number of nodules were calculated for the entire vegetation period, being higher in the inoculated treatment. There was no positive correlation between the content of isoflavones in seeds and the number and mass of nodules. The impact of quantity of isoflavone on nodulation intensity in soybeans was not significant,, which could be related to already saturated soil with nitrogen-fixing bacteria.

In the previous period, research was carried out with a focus on the application of various types of microbiological preparations in order to influence their possible influence on the morphological, productive and qualitative properties of industrial plants. Research was conducted in the period from 2015 to 2023 both in the open field and in laboratory conditions. In the group of industrial plants, oil, protein, medicinal, aromatic and spice plants were investigated. This paper shows the influence of certain biopreparations on the treatment of organic soybean seeds before sowing and during cultivation. For that purpose, mixtures of microbiological strains (Bacillus subtilis, Bacillus licheniformis, Bacillus simplex, Bacillus amiloliquefaciens, Bacillus pumilus, Bacillus megatherium, Bradyrhizobium japonicum and Azotobacter chroococum) were used, with the addition of liquid fertilizers of plant origin enriched with K, Ca and Mg. The use of microbiological strains in the cultivation of organic soybeans has a significant effect on increasing the content of proteins and vegetable oils in soybeans, as well as on the values of morphological parameters and yield in the crop of organically produced soybeans. Microbiological preparations have the potential to contribute to the development of sustainable agricultural systems. The use of selected microbiological cultures for treatment during the inoculation of soil and seeds in the cultivation of industrial plants is reflected in the improvement of the nutritional and functional properties of plants, which are an excellent source of valuable food ingredients.

Edamame is a special soybean ( Glycine max (L.) Merr .) harvested as a vegetable when the seeds are immature (R6 and R7 stage) and have expanded to fill 80 to 90 percent of the pod width. The study was conducted in the experimental field of Federal Scientific Vegetable Center in the Moscow Region in 2020-2022 and Agro-biotechnological department, Agrarian and Technological Institute, RUDN University. The object of research was 3 accessions of soybean ( Glycine max L.): accession A, accession F, Hidaka and Lira. Before sowing, soybean seeds were inoculated with Optimays 400 ( Bradyrhizobium japonicum ) and Biobesta ( Sinorhizobium fredii ). In the field experiment, 10 soybean samples were taken from each plot at the stage of biological ripeness to determine plant height (cm), number of pods per plant, number of stems per plant, stem width (mm), average number of seeds per plant, weight of 1000 seeds (g) and yield (t/ha). The experiment was designed in a complete random block with a factorial arrangement. Thus, we had 4 accessions and 3 treatments (C - control, V1 - Bradyrhizobium japonicum and V2 - Sinorhizobium fredii ) with 3 replacations. The study showed that accession A had the highest average yield per hectare (2.70 t/ha) and weight of 1000 seeds (159 g). Under conditions of the Moscow region, variant V2 ( Sinorhizobium fredii ) had the highest average yield (2.57 t/ha) and weight of 1000 seeds (100.25 g). Therefore, more than 90 % of the results obtained for these two indicators are associated with the use of V2 treatment. For the rest of the studied indicators, no significant differences were found, and they did not affect the efficiency indicators. The combination of accession A and treatment V2 led to the highest average yield (2.99 t/ha). The product based on Sinorhizobium fredii showed the best indicators for all the studied samples.

In soybean production, numerous strategies are utilized to enhance seed quality and mitigate the effects of biotic and abiotic stressors. Zn-based nutrient priming has been shown to be effective for field crops, and biopriming is a strategy that is becoming increasingly important for sustainable agriculture. On the other hand, there is a lack of information about the effect of comprehensive nutrient priming and biopriming techniques on soybean seed quality and viability and seed health. This study was performed to assess the benefits of nutrient priming with Zn, biopriming with Bacillus megaterium and Bradyrhizobium japonicum (single and co-inoculation), and combination of nutrient priming and biopriming on the seed quality and viability, as well as seed infection caused by Alternaria spp. and Fusarium spp. Three different laboratory tests were employed: germination test, accelerated aging test, and seed health test. The results revealed that all tested priming treatments have a beneficial effect on seed germination, initial plant growth, and reduction of seed infection in normal and aged seeds. Additionally, comprehensive priming with Zn, Bacillus megaterium, and Bradyrhizobium japonicum reduced the occurrence of Alternaria spp. (−84% and −75%) and Fusarium spp. (−91% and −88%) on soybean seeds in the germination and accelerated aging tests, respectively, as compared to the control, which proved to be the most effective treatment in both optimal and stressful conditions.

Rhizobacteria are capable of inducing defense responses via the expression of pathogenesis-related proteins (PR-proteins) such as chitinases, and many studies have validated the functions of plant chitinases in defense responses. Soybean (Glycine max) is an economically important crop worldwide, but the functional validation of soybean chitinase in defense responses remains limited. In this study, genome-wide characterization of soybean chitinases was conducted, and the defense contribution of three chitinases (GmChi01, GmChi02, or GmChi16) was validated in Arabidopsis transgenic lines against the soil-borne pathogen Fusarium oxysporum. Compared to the Arabidopsis Col-0 and empty vector controls, the transgenic lines with GmChi02 or GmChi16 exhibited fewer chlorosis symptoms and wilting. While GmChi02 and GmChi16 enhanced defense to F. oxysporum, GmChi02 was the only one significantly induced by Burkholderia ambifaria. The observation indicated that plant chitinases may be induced by different rhizobacteria for defense responses. The survey of 37 soybean chitinase gene expressions in response to six rhizobacteria observed diverse inducibility, where only 10 genes were significantly upregulated by at least one rhizobacterium and 9 genes did not respond to any of the rhizobacteria. Motif analysis on soybean promoters further identified not only consensus but also rhizobacterium-specific transcription factor-binding sites for the inducible chitinase genes. Collectively, these results confirmed the involvement of GmChi02 and GmChi16 in defense enhancement and highlighted the diverse inducibility of 37 soybean chitinases encountering F. oxysporum and six rhizobacteria. [ABSTRACT FROM AUTHOR]

The study investigated the impact of the interaction between soybean and rhizobia on the assimilation apparatus functioning and biomass accumulation in different soybean lines with varying photoperiod sensitivity. Nearly isogenic lines (NILs) of soybean were used, with genes E1, E2, and E3 in different allelic states: Clark (e1E2E3), L80-5879 (E1e2e3), L63-3117 (e1e2E3), and L71-920 (e1e2e3). The experimental group for each line was treated with Bradyrhizobium japonicum 634b. Plants were grown under natural long-day conditions (16 hours). Growth indicators of the studied lines, such as relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR), and specific leaf area (SLA), were analyzed, as well as the content of chlorophylls A and B in the V3 and V5 developmental stages. The results demonstrate that the influence of rhizobia on the functioning of the assimilation apparatus and biomass accumulation depends on the soybean line genotype. In the study, RGR, which characterizes the biomass accumulation rate, has similar trends to those observed with NAR, characterizing the assimilation apparatus's functioning. However, each line showed its own tendencies. For instance, in the short-day variety Clark, under bacterial influence, the value of RGR and NAR decreased. Additionally, LAR and SLA values indicated a reduction in the total photosynthetic surface area and leaf dry matter. Bacterial inoculation did not significantly affect the content of photosynthetic pigments in Clark leaves. Another short-day line, L80-5879, showed no significant impact of bacterial inoculation on biomass accumulation. However, soybean interaction with Bradyrhizobium japonicum 634b led to a decrease in leaf surface area and dry matter content. Probably, bacterial inoculation supported assimilation processes by increasing auxiliary chlorophyll b in photosystem I. A general trend of significant RGR reduction in neutral-day soybean lines, L63-3117 and L71-920, was identified under bacterial influence. The interaction with rhizobia differently affected LAR and SLA values, indicating distinct adaptive mechanisms to the interactions. In conditions of almost zero plant biomass accumulation, Bradyrhizobium japonicum 634b caused a decrease in the total photosynthetic surface area and chlorophyll a and b content in the L63-3117 line. In L71-920, bacterial inoculation had no effect on the total photosynthetic surface area, while leaf dry matter and photosynthetic pigment content decreased. The obtained results demonstrate that interaction with rhizobia can influence the functioning of the assimilation apparatus in soybeans with varying photoperiod sensitivity that is determined by genotype. It is important in improving soybean productivity and its application in agricultural practices. [ABSTRACT FROM AUTHOR]

Bacterial iron export mitigates high iron stress, but a role for it under lower iron conditions has not been established. MbfA is the high iron stress exporter in Bradyrhizobium japonicum. Here, we identify the ihpABC genes in a selection for secondary site mutations that suppress the poor growth phenotype of feoAB mutants defective in iron acquisition. IhpABC belongs to the RND tripartite efflux pump family. High iron conditions that derepress the mbfA gene partially rescued the growth of an ihpC mutant but reverted the feoB ihpC mutant to the feoB growth phenotype. The ihpA mutant grown under low iron conditions accumulated higher levels of iron compared to the wild type, and it displayed aberrant iron‐responsive gene expression. The mbfA mutant was more sensitive than the wild type to H2O2, but the ihpA mutant was not sensitive. The ihpA mutant accumulated more Zn, Co and Cd than was found in the wild type, and growth of the mutant was more sensitive to inhibition by ZnCl2, CoCl2 and CdCl2. The findings suggest that IhpABC is a divalent metal ion exporter that helps maintain iron homeostasis under low to moderate environmental iron levels. Thus, iron export is not limited to managing high iron stress. [ABSTRACT FROM AUTHOR]

Soil salinity is one of the major limiting factors in plant growth regulation. Salinity-tolerant endophytic bacteria (STEB) can be used to alleviate the negative effects of salinity and promote plant growth. In this study, thirteen endophytic bacteria were isolated from mungbean roots and tested for NaCl salt-tolerance up to 4%. Six bacterial isolates, TMB2, TMB3, TMB5, TMB6, TMB7 and TMB9, demonstrated the ability to tolerate salt. Plant growth-promoting properties such as phosphate solubilization, indole-3-acetic acid (IAA) production, nitrogen fixation, zinc solubilization, biofilm formation and hydrolytic enzyme production were tested in vitro under saline conditions. Eight bacterial isolates indicated phosphate solubilization potential ranging from 5.8-17.7 µg mL-1, wherein TMB6 was found most efficient. Ten bacterial isolates exhibited IAA production ranging from 0.3-2.1 µg mL-1, where TMB7 indicated the highest potential. All the bacterial isolates except TMB13 exhibited nitrogenase activity. Three isolates, TMB6, TMB7 and TMB9, were able to solubilize zinc on tris-minimal media. All isolates were capable of forming biofilm except TMB12 and TMB13. Only TMB2, TMB6 and TMB7 exhibited cellulase activity, while TMB2 and TMB7 exhibited pectinase production. Based on in vitro testing, six efficient STEB were selected and subjected to the further studies. 16S rRNA gene sequencing of efficient STEB revealed the maximum similarity between TMB2 and Rhizobium pusense, TMB3 and Agrobacterium leguminum, TMB5 and Achromobacter denitrificans, TMB6 and Pseudomonas extremorientalis, TMB7 and Bradyrhizobium japonicum and TMB9 and Serratia quinivorans. This is the first international report on the existence of A. leguminum, A. denitrificans, P. extremorientalis and S. quinivorans inside the roots of mungbean. Under controlled-conditions, inoculation of P. extremorientalis TMB6, B. japonicum TMB7 and S. quinivorans TMB9 exhibited maximum potential to increase plant growth parameters; specifically plant dry weight was increased by up to 52%, 61% and 45%, respectively. Inoculation of B. japonicum TMB7 displayed the highest potential to increase plant proline, glycine betaine and total soluble proteins contents by 77%, 78% and 64%, respectively, compared to control under saline conditions. It is suggested that the efficient STEB could be used as biofertilizers for mungbean crop productivity under saline conditions after field-testing. [ABSTRACT FROM AUTHOR]

Background. With the increase in soybean cultivation areas, inoculants are becoming increasingly sought after. They are not only compatible with the original preparations for seed treatment of soybean but also offer the possibility of applying them for several days or even months before sowing into the soil. Objective. The viability of new strains of nodule bacteria Bradyrhizobium japonicum (strain PC07 and strain B78) was investigated on the surface of soybean seeds treated with fungicides Fever and Maxim XL during the extended storage of inoculated seeds. Additionally, their ability for nitrogen fixation under symbiotic conditions was evaluated. Methods. Сultivation, serial dilution method, determination of bacterial titer of inoculants, quantification of colony forming units (CFU), gas chromatography. Results. In laboratory conditions, on the soybean seeds of Almaz and Vasylkivska varieties, the viability of the nodule bacteria B. japonicum PC07 and B78, which are more resistant to the active substances of these fungicides in pure culture, decreased. This reduction was dependent on the storage period, the fungicide used, and the strain of inoculant. One day after inoculation on the seeds without the use of fungicide, 68.6–75.4% CFU of the initial number was retained. Seeds treated with the fungicide Fever contained 36.5–38.3% CFU, and those treated with Maxim XL contained 26.2–27.0% CFU. The use of inoculants based on fungicide-resistant strains of B. japonicum PC07 and B78 also provided high cell viability – 2.41–2.8×106 (on the seeds without treatment), 1.40–1.70×106 (with Fever) and 0.8–1.17×106 (with Maxim XL) CFU/seed after 5 days of storage. The nitrogen-fixing activity of root nodules in soybean plants of Almaz and Vasylkivska varieties, whose seeds were treated with Fever, decreased on both varieties by 18.4–22.4% and 32.1–39.5%, respectively and for treatment with Maxim XL, the reduction was 24.5–33.7% and 47.7–75.2%, respectively, during the storage of seeds for 5 and 7 days before sowing, compared to control variants (seeds without fungicide treatment). Conclusions. The utilization of fungicide-resistant strains of B. japonicum PC07 and B78 for bacterization of soybean seeds treated with fungicides Fever and Maxim XL provides a high inoculation titer during 5 days of storage. Viability of microbial cells on seeds treated with fungicides significantly diminishes during storage for more than 7–14 days. Insufficient titer of CFU of B. japonicum strains PC07 and B78 on the seed surface after 14 days of storage can considerably impede the efficacy of biopreparations. Therefore, it is crucial to seek substances that can enhance the resistance of rhizobia on seeds to the adverse effects of fungicide seed treatment, ensuring a longer period of their viability.

The root nodule bacteria are utilized in the production of natural biological fertilizers to achieve clean agriculture by reducing chemical fertilizers. Therefore, the bacterial inoculum was prepared from local isolates of Rhizobium leguminosarum and Bradyrhizobium japonicum, which were morphologically and molecularly characterized. Subsequently, the efficacy of the prepared inoculum was tested in the formation of root nodules and some growth traits of mung bean plants in gypsiferous soil at three levels of nitrogen fertilization (0, 40, 80) kg N ha-1 The results showed a significant increase in all plant growth traits during the flowering stage for the treatments inoculated with Rhizobium leguminosarum and Bradyrhizobium japonicum bacteria in comparison to the treatment without inoculation. The inoculated treatments outperformed the non-inoculated treatment significantly. Additionally, the treatment inoculated with Bradyrhizobium japonicum showed a significant superiority over the treatment inoculated with Rhizobium leguminosarum in all studied growth traits, the recorded values for the count of root nodules were (0.00, 8.33, 35.11) nodule. plant-1, The wet mass of nodules was (0.00, 0.091, 1.802) g. plant-1, and dry mass of nodules was (0.00, 0.010, 0.337) g. plant-1. The plant height was (52.11, 56.22, 58.05) cm. plant-1. The dry mass of the vegetative part, was (14.03, 20.10, 23.05) g. plant-1, and, the dry mass of the root part was (1.37, 2.57, 2.67) g. plant-1. The nitrogen content was (1.547, 2.765, 3.028) % phosphorus (0.121, 0.236, 0.377) %, and potassium (1.168, 2.342, 3.562) % in the vegetative part. The absorbed nitrogen in the vegetative part was (217.41, 541.10,718.02) mg. plant-1. These values were recorded for the non-inoculated treatment, Rhizobium leguminosarum inoculated treatment, and Bradyrhizobium japonicum inoculated treatment, respectively. The results showed a significant superiority for the 40 kg N ha-1 fertilized treatment in comparison to both the unfertilized treatment and the 80 kg N/ha-1 fertilized treatment in all studied traits. The interaction effect was significant, as the treatment that was inoculated with Bradyrhizobium japonicum and 40 kg N ha-1 fertilized treatment exhibited significant superiority over the other treatments in all studied traits.

Soybean (Glycine max L.) is a very important legume in the human diet as well as fodder crop. Previous studies have reported that co-inoculation with PGPR (plant growth-promoting bacteria) and rhizobia promotes symbiotic nitrogen fixation efficiency, increases plant nitrogen content and reduces the occurrence of soybean diseases, thus reducing pesticide use, and protecting the environment. The aim of this study was to determine the impact of co-inoculation of soybean seeds with different strains of nodule bacteria Bradyrhizobium japonicum as well as PGPR (Pseudomonas fluorescens). Indigenous strains of beneficial bacteria used in this research were isolated from different locations in Croatia. Isolates were identified by performing 16S rRNA gene sequencing. The application of different strains of nodule bacteria resulted in a statistically justified effect on all investigated properties, with the exception of root length. A positive influence of P. fluorescens on the increase in shoot dry weight was observed with the co-inoculation with the reference strain B. japonicum and two indigenous strains. The application of P. fluorescens did not show statistically justified differences in any of the investigated properties. Co-inoculation of nodules and PGPR bacteria is a very important biotechnological tool in agriculture, which is why research in this area should definitely be continued and expanded to a larger number of P. fluorescens strains.

Background: Rhizobial inoculation in combination with fungicidal seed treatment is an effective solution for improving soybean resistance to modern climate changes due to the maximum implementation of the plant’s stress-protective antioxidant properties and their nitrogen-fixing potential, which will contribute to the preservation of the environment. Methods: Model ecosystems at different stages of legume–rhizobial symbiosis formation, created by treatment before sowing soybean seeds with a fungicide (fludioxonil, 25 g/L) and inoculation with an active strain of Bradyrhizobium japonicum (titer 109 cells per mL), were subjected to microbiological, biochemical, and physiological testing methods in controlled and field conditions. Results: Seed treatment with fungicide and rhizobia showed different patterns in the dynamics of key antioxidant enzymes in soybean nodules under drought conditions. Superoxide dismutase activity increased by 32.7% under moderate stress, while catalase increased by 90.6% under long-term stress. An increase in the antioxidant enzyme activity induced the regulation of lipoperoxidation processes during drought and after the restoration of irrigation. Regeneration after stress was evident in soybean plants with a combination of fungicide seed treatment and rhizobial inoculant, where enzyme levels and lipoperoxidation processes returned to control plant levels. Applying seed treatment with fungicide and Rhizobium led to the preservation of the symbiotic apparatus functioning in drought conditions. As proof of this, molecular nitrogen fixation by nodules has a higher efficiency of 25.6% compared to soybeans without fungicide treatment. In the field, fungicidal treatment of seeds in a complex with rhizobia inoculant induced prolongation of the symbiotic apparatus functioning in the reproductive period of soybean ontogenesis. This positively affected the nitrogen-fixing activity of soybeans during the pod formation stage by more than 71.7%, as well as increasing soybean yield by 12.7% in the field. Conclusions: The application of Rhizobium inoculant and fungicide to seeds contributed to the development of antioxidant protection of soybean plants during droughts due to the activation of key enzymatic complexes and regulation of lipoperoxidation processes, which have a positive effect on nitrogen fixation and productivity of soybeans. This is a necessary element in soybean agrotechnologies to improve plant adaptation and resilience in the context of modern climate change.

Soybean [Glycine max (L.) Merr.] is one of the most important and oldest crops. Due to its ability to form symbiotic interactions with nitrogen-fixing bacteria, it is a valuable source of nitrogen for agriculture and proteins for humans and livestock. In Europe, for instance, in Poland, the soybean cultivation area is still not large but is gradually increasing due to climate change. The lack of indigenous soybean microsymbionts in Polish soils forces the application of commercial strains to establish effective symbioses. Fast and reliable identification methods are needed to study the persistence, competitiveness, and dispersal of bradyrhizobia introduced as inocula. Our study aimed to apply real-time PCR coupled with high-resolution melting curve (HRM) analysis to detect and differentiate bacterial strains occupying soybean nodules. HRM-PCR was performed on crude extracts from nodules using primers specific for recA, a highly conserved nonsymbiotic gene. By comparing them with the reference strains, we were able to identify and assign Bradyrhiobium strains that had been introduced into field locations in Poland. In conclusion, HRM analysis was proven to be a fast and accurate method for identifying soybean microsymbionts and might be successfully used for identifying other legume-nodulating bacteria.

Soil salinity is one of the major limiting factors in plant growth regulation. Salinity-tolerant endophytic bacteria (STEB) can be used to alleviate the negative effects of salinity and promote plant growth. In this study, thirteen endophytic bacteria were isolated from mungbean roots and tested for NaCl salt-tolerance up to 4%. Six bacterial isolates, TMB2, TMB3, TMB5, TMB6, TMB7 and TMB9, demonstrated the ability to tolerate salt. Plant growth-promoting properties such as phosphate solubilization, indole-3-acetic acid (IAA) production, nitrogen fixation, zinc solubilization, biofilm formation and hydrolytic enzyme production were tested in vitro under saline conditions. Eight bacterial isolates indicated phosphate solubilization potential ranging from 5.8–17.7 μg mL−1, wherein TMB6 was found most efficient. Ten bacterial isolates exhibited IAA production ranging from 0.3–2.1 μg mL−1, where TMB7 indicated the highest potential. All the bacterial isolates except TMB13 exhibited nitrogenase activity. Three isolates, TMB6, TMB7 and TMB9, were able to solubilize zinc on tris-minimal media. All isolates were capable of forming biofilm except TMB12 and TMB13. Only TMB2, TMB6 and TMB7 exhibited cellulase activity, while TMB2 and TMB7 exhibited pectinase production. Based on in vitro testing, six efficient STEB were selected and subjected to the further studies. 16S rRNA gene sequencing of efficient STEB revealed the maximum similarity between TMB2 and Rhizobium pusense, TMB3 and Agrobacterium leguminum, TMB5 and Achromobacter denitrificans, TMB6 and Pseudomonas extremorientalis, TMB7 and Bradyrhizobium japonicum and TMB9 and Serratia quinivorans. This is the first international report on the existence of A. leguminum, A. denitrificans, P. extremorientalis and S. quinivorans inside the roots of mungbean. Under controlled-conditions, inoculation of P. extremorientalis TMB6, B. japonicum TMB7 and S. quinivorans TMB9 exhibited maximum potential to increase plant growth parameters; specifically plant dry weight was increased by up to 52%, 61% and 45%, respectively. Inoculation of B. japonicum TMB7 displayed the highest potential to increase plant proline, glycine betaine and total soluble proteins contents by 77%, 78% and 64%, respectively, compared to control under saline conditions. It is suggested that the efficient STEB could be used as biofertilizers for mungbean crop productivity under saline conditions after field-testing.

In previous years, the serological and genetic diversities of soybean nodule bacteria in agrocenoses of Ukraine have been researched. Less attention was paid to the study of their survival in the soil. Taking into account the natural heterogeneity of bacteria of the genus Bradyrhizobium, the aim of this work was to evaluate the diversity of bradyrhizobia in local populations of different soils after a long-term period without leguminous plants, to obtain new isolates of nodule bacteria and to study their properties. Methods. Microbiological (isolation of bradyrhizobia from the nodules of trap plants, study of the properties of strains), serological (study of the diversity of rhizobia in nodule populations, study of the serological affiliation of strains), vegetation and field experiments (study of plant infecting with bradyrhizobia). Results. Local populations of bradyrhizobia in sod-podzolic soil and leached chornozem were studied using trap plants of the genera Glycine, Vigna, and Lupinus. It was established that after a 7 to 8-year period without leguminous plants, active nodule bacteria remained in both types of soil, which nodulated cultivated and wild soybeans, cowpeas, mung beans, adzuki beans, and lupine. The main microsymbionts of plants of the genera Glycine and Vigna on different types of soil were soybean bradyrhizobia belonging to 6 serological groups: 46, M8, КВ11, 634b, HR, and B1. The representatives of 4 serogroups corresponded to the inoculant strains of Bradyrhizobium japonicum 46, M8, 634b, and КВ11, which were periodically used in the studied areas. In addition to B. japonicum, cowpea plants trapped microsymbionts of B. lupini serogroup 367a (4.2%) from the soil. Bradyrhizobia of serogroup B1 were detected both in nodules of cowpea (6.3%) and wild soybean (12.5%). 45.8% of lupine nodules were formed by bacteria B. lupini of serogroup 367a. The appearance in populations of representatives of serogroups HR and B1 along with a group of unidentified microsymbionts requires further research. Cultivation of trap plants of wild soybeans and various types of cowpea made it possible to identify saprophytic strain B. japonicum M8 (formed 25.0% to 83.4% of nodules) in the sod-podzolic soil, which did not infect the roots of cultivated soybeans. 70 isolates of bradyrhizobia were obtained from nodules of trap plants, which were preliminarily identified as B. japonicum, B. lupini, and Bradyrhizobium sp. Conclusions. The results confirm the importance of using different leguminous trap plants for a more complete characterization of the local rhizobial community. Cultivation of plants of the genera Glycine, Vigna, and Lupinus, capable of cross-infection, made it possible to detect bacteria B. japonicum (serogroups 46, M8, КВ11, 634b, HR), B. lupini (serogroup 367a), and Bradyrhizobium sp. (serogroup B1), which exist for a long-term period as saprophytes in sod-podzolic soil and leached chornozem. 70 isolates of bradyrhizobia were obtained, 35 of which were serologically related to the inoculant strains of B. japonicum introduced into the agrocenosis at the beginning of the research. [ABSTRACT FROM AUTHOR]

The soybean [Glycine max (L.) Merrill] relationship with the bacteria Bradyrhizobium japonicum is responsible for providing around 60% of the nitrogen (N) required for the crop and the remaining N comes from the soil or supplemental fertilization. To investigate if higher yields are possible, supplemental N studies and co-inoculation of Rhizobium with Azospirillum are necessary. This N rate (0, 30, 56, 112, 336 kg N ha−1) and inoculation study was conducted across eight environments in eastern North Dakota, USA, in 2021 and 2022. Also, the effect of supplemental N and co-inoculation on nodulation was evaluated. When N was applied at 112 kg N ha−1, nodulation was significantly inhibited. Co-inoculation increased the number of large nodules and the volume of nodules; however, the yield was not different from inoculation with B. japonicum. Nitrogen at 112 and 336 kg ha−1 increased grain yield, protein yield, and seed weight; however, the higher N rate decreased plant population. There were significant positive relationships between yield and protein content and seed weight, and negative relationships between oil and protein content, and yield and oil content. Based on a polynomial relationship, the highest yield (3711 kg ha−1) would be achieved at 273 kg N ha−1. The application of N resulted in a yield increase but using current prices may not be an economical choice. Additional research is necessary to verify if co-inoculation with efficient strains can improve biological N fixation. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Kirkuk University for Agricultural Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) 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.)

Rhizobium is a Gram-negative bacterium, which dissolves minerals, produces growth hormones, promotes root growth, and protects plants from different soil-borne pathogens. In the present study, roots, stalks, and fresh weight of maize (Zea mays L.) were significantly increased after soaking in Bradyrhizobium japonicum compared with the control. Subsequently, transcriptome sequencing results of the whole maize plant soaked in B. japonicum showed that multiple growth and development-related genes were up-regulated more than 100-fold compared to the control. Furthermore, the abundance of plant growth promoting bacteria, such as Acidobacteria Subgroup_6 and Chloroflexi KD4-96, were increased significantly. On the contrary, the abundance of multiple pathogens, such as Curvularia, Fusarium and Mycocentrospora, were significantly decreased. Moreover, inoculation with B. japonicum could inhibit the infection of the pathogen Fusarium graminearum in maize. These results suggest that soaking seeds in B. japonicum may affect the expression of maize growth and development-related genes as the bacteria changes the soil microorganism community structure. These findings may help to expand the application of B. japonicum in crop production and provide new opportunities for food security. [ABSTRACT FROM AUTHOR]

The efficiency of the natural symbiotic relationship between communally produced legumes and nitrogen fixing bacteria has been reported to be very poor, mainly due to poor soils in communal farming areas. With the use of synthetic fertilizers to increase soil fertility being both environment-unfriendly and unaffordable for majority of communal farmers, strategies that are cost-effective and climate smart need to be put in place to improve the productivity of communal legumes such as Bambara groundnuts. A 5 x 3 factorial arrangement experiment in a randomised complete block design with five replications was established under greenhouse conditions. Factors consisted of bacterial species: [Bradyrhizobium japonicum (Bj), Rhizobium loti (Rl), Rhizobium meliloti (Rm), Rhizobium leguminosarum biovar phaseoli (Rlt) and a negative control (untreated)], and local Bambara groundnut varieties: black, creamy white-eye, and red. Bambara groundnut seeds were inoculated with levels recommended for cowpea and soyabean. Nitrogen fixing bacteria application on Bambara groundnuts increased plant growth and nodulation variables, with the effects varying with Bambara groundnut variety and rhizobium type. Bj outperformed the other tested bacteria on nodulation variables, with the red cultivar performing better in all growth variables, making it suitable for pod and vegetative production. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central European Agriculture is the property of Journal of Central European Agriculture 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.)

The effect of individual nanometals (Co, Fe, Cu, Ge) carboxylates (NMC) as components of the suspension for seeds inoculation with rhizobia on the nitrogen fixation rate and the parameters of CO2 and H2O gas exchange in soybean plants grown under different water conditions was investigated. The scheme of trials included the following variants: 1 - seeds + strain B1-20; 2 - seeds + (strain B1-20 + nano-cobalt carboxylate); 3 - seeds + (strain В1-20 + nano-ferrum carboxylate); 4 - seeds + (strain B1-20 + nano-cuprum carboxylate); 5 - seeds + (strain B1-20 + nano-germanium carboxylate). The results showed that during the flowering period, drought (30% field capacity) significantly reduced the rates of nitrogen fixation (Nfx), CO2 net assimilation (An), and transpiration (Tr) in soybean plants. Inoculation of seeds by rhizobia with NMC before sowing reduced the negative effect of drought on these physiological processes. Close correlations were found between the rates of Nfx and An and the stomatal conductance for CO2 and An rates. It was concluded that pre-sowing treatment of seeds by rhizobia with NMC mitigates the negative effect of drought on the main components of soybean-rhizobia symbiosis productivity formation - nitrogen fixation and CO2 assimilation, and also contributes to their recovery after the removal of the stressor. The most effective for this was the use of Ge and Fe nanoparticle carboxylates.

Antimicrobial silver nanoparticles (AgNPs) are popular in consumer and industrial products, leading to increasing concentrations in the environment. We tested whether exposure to AgNPs could be detrimental to a microbe, its host plant, and their symbiotic relationship. When subjected to 10 µg/mL AgNPs, growth of Bradyrhizobium japonicum USDA 110 was halted. Axenic nitrogen-fertilized Glycine max seedlings were unaffected by 2.5 µg/mL of 30 nm AgNPs, but growth was inhibited with the same dose of 16 nm AgNPs. With 2.5 µg/mL AgNPs, biomass of inoculated plants was 50% of the control. Bacteroids were not found in nodules on plants treated with 2.5 µg/mL AgNPs and plants given 0.5–2.5 µg/mL AgNPs had 40–65% decreased nitrogen fixation. In conclusion, AgNPs not only interfere with general plant and bacterial growth but also inhibit nodule development and bacterial nitrogen fixation. We should be mindful of not releasing AgNPs to the environment or to agricultural land. [ABSTRACT FROM AUTHOR]

The legume-rhizobium interaction induces formation of specific reactions that take metabolism in the host plant up to a new functional level, increasing its tolerance to unfavourable cultivation conditions. Our objective was to study the participation of key enzymes – phenylalanine ammonia lyase, guaiacol peroxidase, and polyphenol oxidases – in the phenol-metabolism processes and synthesis of a broad spectrum of secondary metabolites in soybean plants that have established symbiotic interactions with rhizobia of varying effectiveness during optimal and insufficient water supplies. In our studies, we used symbiotic systems of soybean and rhizobia (Bradyrhizobium japonicum) that varied in efficiency and virulence. In the period of active nitrogen fixation by soybean, from the third-true-leaf stage until budding, we created different water-supply regimes for the plants, including optimal watering at the level of 60% of full field capacity (control) and insufficient, at the level of 30% (drought). When the soybean was flowering, we recovered the optimal level of water supply (resumed watering). In the studies, we employed microbiological, biochemical, and physiological approaches. We determined the specificity of how key enzymes of the phenol metabolism such as phenylalanine ammonia lyase, polyphenol oxidase and guaiacol peroxidase in the nodules, roots, and leaves of the soybean reacted to different levels of water supply, depending on the functional efficiency of the symbiotic system involving strains of B. japonicum, varying in effectiveness and virulence. In the effective soybean-rhizobium symbiosis, there occurred insignificant changes in the activity of phenol-metabolism enzymes in the nodules, roots, and leaves during drought and after action of the stress. This evidence is that in symbiosis with effective rhizobia B1-20, soybean could realize its own defensive systems that regulate optimal functioning of phenol metabolism in dehydration conditions. In the low-effective 107 and ineffective 604k symbiotic systems of soybean, there was observed unstable dynamics of the activity of enzymes in leaves and roots, manifested in intensification or inhibition of their activity levels during drought or post-stress period. This indicates malfunctioning of the processes associated with phenol metabolism in the soybean plants. We concluded that tolerance of legume-rhizobium symbiosis to water deprivation depends on mutual involvements of the both symbiotic partners – host plant and rhizobia, their ability to fully realize the defensive systems for activation of the key enzymatic complexes taking part in regulation of phenol metabolism in plants.

The intensity of drought-induced oxidative processes by the degree of superoxide anion radical generation and the activity of NADPH oxidase in soybean associated with different activity and virulence of Bradyrhizobium strains were studied. The importance of active Bradyrhizobium japonicum for the formation of effective symbiosis with soybean to improve the realization of the adaptive potential of plants during drought and post-stress period has been established. Increased NADPH oxidase activity in nodules (by 3.5 – 4.7 times), as well as excessive production of superoxide radical in nodules (by 1.5 – 2 times) and roots (from 113 to 323%) of soybean in symbiosis with efficient Bradyrhizobium strains were observed during drought. However, the development of oxidative processes in effective soybean-rhizobial symbioses slowed down after exposure to stress. This indicates the adaptation of soybean plants associated with active Bradyrhizobium strains to growing conditions. In symbiotic systems with ineffective Bradyrhizobium strains, a significant increase in NADPH oxidase activity in nodules (by 3.3 – 6.0 times) and intensification of superoxide radical formation in nodules (by 2 – 3 times) and roots (from 260 to 330%) recorded both under drought and post-stress period. This indicates a significant development of oxidative processes and the inability to realize the adaptive potential of soybean plants in symbiosis with ineffective Bradyrhizobium strains. Thus, excessive formation of the superoxide radical and an increase in the activity of NADPH oxidase indicate the appearance of oxidative processes, which are a typical reaction in response to drought in soybean-rhizobial symbioses of varying efficiency. At the same time, the development of oxidative processes depends on the ability of soybean plants in symbiosis with Bradyrhizobium japonicum to realize their adaptive potential in during drought and post-stress period.

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. [ABSTRACT FROM AUTHOR]

Photoperiod, which regulates the duration of vegetative and generative development, and the plant-microorganism interaction, which influences the metabolic status of plant organisms, are important factors in the regulating plant growth and development. The aim of the study was to determine the influence of Glycine max (L.) Merr. genotype and seed pre-bacterization with a virulent and active strain of Bradyrhizobium japonicum 634b on the plant growth and development, and on the soluble carbohydrate content in leaves of isogenic by E-genes lines under field conditions. Nearly isogenic lines (NILs) of soybean, in which the E1, E2, and E3 genes are located at different allelic loci, were used. Sterile seeds were pretreated with distilled water (control) and Bradyrhizobium japonicum 634b cell suspension (experiment). Plants were grown under natural long-day conditions (16 hours). The growth and development of the soybean were evaluated by phenological observations, morphometric indicators fixed at the V3 and V5 developmental stages, relative growth rate (RGR), and the content of soluble sugars - mono- and oligosaccharides. The effect of the factors studied (genotype, bacterization, and their interaction) was calculated. The results of the experiment and the calculation of the effect of the factor showed that the isoline genotype has the greatest effect on seed germination, phenological development of the plant and duration of the VE-R1 phase, growth of the root system in the V3 and V5 phases, and the content of monosaccharides involved in forming the plant-microorganism interaction. The effect of bacterization is most evident in the RGR, shoot development, and the oligosaccharide content of the leaves of NILs in the V3 and V5 phases. Among the isolines studied, L 80-5879, which has the E1 gene (flowering repressor) in a dominant state, was characterized by minimal sensitivity to bacterization. It was found that bacterization and genotype interaction didn't influence the VE-R1 duration stage and the shoot and root length. The results obtained therefore prove that the E-series genes, which determine the photoperiodic sensitivity of soya beans, can also be indirectly involved in establishing plant-microorganism interactions. [ABSTRACT FROM AUTHOR]

The use of rhizobia and phosphorus solubilizing bacteria (PSB) as an alternative source to improve soil nutrition is necessary to promote sustainable gram production. In this study, the efficacy of rhizobia (Bradyrhizobium japonicum- BR3267) and PSB (Pseudomonas striata) in liquid form and on carrier material was investigated in a Randomized Complete Block Design. Their effects on root nodulation, nutrient uptake, growth phenology, and yield of black gram were evaluated. Recommended fertilizer dose (RDF)- 200 kg ha−1 N P K (12:30:17) + 0.4 Zn was set as the control and common factor. Integration of Rhizobia + RDF increased plant height, dry matter, leaf chlorophyll, and leaf area index compared to PSB + RDF. The liquid inoculants influenced root nodulation, N and P uptake, growth phenology, and yield more than the carrier-based. Root nodule number plant−1 was highest with Rhizobia + RDF, but root nodule volume and weight increased when PSB was integrated. Nitrogen uptake correlated positively with nodule number (R2 = 0.64) and dry weight (R2 = 0.75). The integrated liquid-based Rhizobia + PSB + RDF produced the highest yield (1268.31 kg ha−1) and was 35% higher than the non-inoculated plot. The higher RDF + Rhizobium + PSB (LB) + RDF trend resulted in a significant aggregate mean of 21.5%, and protein yield (272.77 kg ha−1). The study addressed the hypothesis that rhizobia and PSB in liquid form have a stronger effect on nodulation, which positively affects nutrient uptake capacity and overall crop productivity, so their dual inclusion with RDF in cropping systems is recommended. [ABSTRACT FROM AUTHOR]

The effect of carmoisine (azorubin) on the viability and reproduction of Bradyrhizobium japonicum (Kirchner, 1896), Jordan, 1982 in vitro and on the physiological parameters of soybean plants under conditions of symbiosis with the bacteria was studied. Sensitivity to carmoisine of selected strains of B. japonicum – 634b, 646, 614, M8, PC07, PC09, PC10 and Tn5-mutants of B. japonicum 646 – B20, B78, B144 was studied by the "hole method". It was determined that B. japonicum strains are not sensitive to carmoisine in concentrations of 0.25-1.0%, because when growing rhizobia on the surface of mannitol-yeast agar, the zones of inhibition of culture growth around the "holes" with solutions of synthetic colorant were absent. In pot experiments, the physiological response of Glycine max (L.) Merr. plants of the Almaz variety to inoculation was studied by biological preparations based on B. japonicum B78 and PC07 with carmoisine in their composition. It was shown that the studied biological products had no negative impact on plant growth and development compared to the control, and on the contrary, it contributed to the activization of biosynthetic processes, e.g., the soybean stems linear growth, the growth of aboveground mass and root system, and the chlorophylls and carotenoids accumulation during growing season.

Understanding the beneficial plant-microbe interactions is becoming extremely critical for deploying microbes imparting plant fitness and achieving sustainability in agriculture. Diazotrophic bacteria have the unique ability to survive without external sources of nitrogen and simultaneously promote host plant growth, but the mechanisms of endophytic interaction in cereals and legumes have not been studied extensively. We have studied the early interaction of two diazotrophic bacteria, Gluconacetobacter diazotrophicus (GAB) and Bradyrhizobium japonicum (BRH), in 15-day-old seedlings of rice and soybean up to 120 h after inoculation (hai) under lownitrogen medium. Root colonization of GAB in rice was higher than that of BRH, and BRH colonization was higher in soybean roots as observed from the scanning electron microscopy at 120 hai. Peroxidase enzyme was significantly higher at 24 hai but thereafter was reduced sharply in soybean and gradually in rice. The roots of rice and soybean inoculated with GAB and BRH harvested from five time points were pooled, and transcriptome analysis was executed along with control. Two pathways, "Plant pathogen interaction" and "MAPK signaling," were specific to Rice-Gluconacetobacter (RG), whereas the pathways related to nitrogen metabolism and plant hormone signaling were specific to Rice-Bradyrhizobium (RB) in rice. Comparative transcriptome analysis of the root tissues revealed that several plant-diazotroph-specific differentially expressed genes (DEGs) and metabolic pathways of plant-diazotroph-specific transcripts, viz., chitinase, brassinosteroid, auxin, Myeloblastosis (MYB), nodulin, and nitrate transporter (NRT), were common in all plant-diazotroph combinations; three transcripts, viz., nitrate transport accessory protein (NAR), thaumatin, and thionin, were exclusive in rice and another three transcripts, viz., NAC (NAM: no apical meristem, ATAF: Arabidopsis thaliana activating factor, and CUC: cup-shaped cotyledon), ABA (abscisic acid), and ammonium transporter, were exclusive in soybean. Differential expression of these transcripts and reduction in pathogenesisrelated (PR) protein expression show the early interaction. Based on the interaction, it can be inferred that the compatibility of rice and soybean is more with GAB and BRH, respectively. We propose that rice is unable to identify the diazotroph as a beneficial microorganism or a pathogen from an early response. So, it expressed the hypersensitivity-related transcripts along with PR proteins. The molecular mechanism of diazotrophic associations of GAB and BRH with rice vis-à-vis soybean will shed light on the basic understanding of host responses to beneficial microorganisms. [ABSTRACT FROM AUTHOR]

Phytohormones are important in the main pathways of transduction of symbiotic signals between macro- and microsymbionts, and understanding of their participation in integration with other metabolic pathways, including prooxidant-antioxidant systems, is crucial in the formation of diff erent-effi ciency symbiotic systems. Aim. To investigate the eff ect of salicylic acid (SA, 50 μM) and methyl jasmonate (MJ, 0.75 μM) as components of the cultivation media of diff erent in the activity and virulence rhizobia 604k and B1-20 on the peculiarities of the formation of symbiotic systems in terms of intensity and activity of catalase, as well as on the course of nodulation and nitrogen fi xation. Methods. Microbiological (cultivation of nitrogen-fi xing microorganisms, seed inoculation), physiological (vegetation experiment), biochemical (spectrophotometry, gas chromatography), and statistical. Results. It was found that the use of SA (50 μM) as an additional component of the culture medium of active rhizobia Tn5-mutant B1-20 for seed inoculation induces increased levels of peroxide production and catalase activity in soybean roots in the early stages of symbiosis, which contributes to the eff ectiveness of its symbiotic apparatus. Addition of MJ (0.75 μM) to the culture medium of rhizobia B1-20 does not aff ect changes in peroxide content and catalase activity in the roots, however, stimulates the processes of nodulation and reduces nitrogen fi xation. It has been shown that modifi cation of the cultivation medium of inactive rhizobia of the highly virulent strain 604k using SA (50 μM) or MJ (0.75 μM) does not change the peroxide content and leads to an increase in catalase activity in soybean roots during the formation of an ineff ective symbiotic system with activation of nodulation processes. Conclusions. When using SA (50 μM) or MJ (0.75 μM) as components of the culture medium for rhizobia of diff erent activity and virulence (604k and B1-20), diff erences were recorded in the levels of functioning of pro-antioxidant systems, in particular, in the production of peroxides and active catalase complexes, at the early stages of the formation of symbiotic systems of Glycine max — Bradyrhizobium japonicum, which aff ects the intensity of the processes of nodulation and nitrogen fixation. [ABSTRACT FROM AUTHOR]

The effect of individual nanometals (Co, Fe, Cu, Ge) carboxylates (NMC) as components of the suspension for seeds inoculation with rhizobia on the nitrogen fixation rate and the parameters of CO2 and H2O gas exchange in soybean plants grown under different water conditions was investigated. The scheme of trials included the following variants: 1 - seeds + strain B1-20; 2 - seeds + (strain B1-20 + nano-cobalt carboxylate); 3 - seeds + (strain B1-20 + nano-ferrum carboxylate); 4 - seeds + (strain B1-20 + nano-cuprum carboxylate); 5 - seeds + (strain B1-20 + nano-germanium carboxylate). The results showed that during the flowering period, drought (30% field capacity) significantly reduced the rates of nitrogen fixation (Nfx), CO2 net assimilation (An), and transpiration (Tr) in soybean plants. Inoculation of seeds by rhizobia with NMC before sowing reduced the negative effect of drought on these physiological processes. Close correlations were found between the rates of Nfx and An and the stomatal conductance for CO2 and An rates. It was concluded that pre-sowing treatment of seeds by rhizobia with NMC mitigates the negative effect of drought on the main components of soybean-rhizobia symbiosis productivity formation - nitrogen fixation and CO2 assimilation, and also contributes to their recovery after the removal of the stressor. The most effective for this was the use of Ge and Fe nanoparticle carboxylates. [ABSTRACT FROM AUTHOR]

Insufficient water supply is one of the main factors that significantly reduce the activity of nitrogen fixation by legume-rhizobial symbiotic systems. That is why comprehensive research on aspects of their resistance to water stress and the search for scientifically substantiated ways to improve the existing ones and develop modern, competitive technologies of growing legumes in arid conditions are becoming especially relevant. The aim of the work was to investigate the processes of formation and functioning of soybean-rhizobial symbiotic systems developed under conditions of different water supply and influence of nanocarboxylates of cobalt, ferum, germanium, chromium, сuprum and molybdenum. The nanoparticles of specified metal nanocarboxylates were used as components of the inoculation suspension of rhizobia of Tn5 mutant B1-20 for soybean seed treatment. A model drought lasting 14 days was created by controlled irrigation. Microbiological and physiological research methods were used in the study. We determined that insufficient water supply caused a significant decrease in the nodulation potential of rhizobia and the intensity of molecular nitrogen fixation by symbiotic systems formed with the participation of soybean plants and nodule bacteria without adding these metal nanocarboxylates to the inoculation suspension. Application of most of the metal nanocarboxylates used as components of the inoculation suspension mitigated the negative impact of stress on the investigated parameters. The study revealed the stimulating effect of cobaltnanocarboxylate on the activity of molecular nitrogen fixation, which was more pronounced in the conditions of insufficient water supply. Symbiotic soybean systems formed with the participation of nodule bacteria containing germaniumcarboxylate nanoparticles were proved to be the least sensitive to the negative impact of insufficient water supply. This was indicated by high rates of nodulation and nitrogen-fixing activity compared with other studied symbiotic systems. We confirmed that the addition of chromium nanocarboxylate to the inoculation suspension of rhizobia provided the highest rates of nodulation and nitrogen-fixing activity of soybean root nodules under optimal growing conditions and, at the same time, had no noticeable positive effect under water stress. We determined that сuprum and molybdenum nanocarboxylates, as components of the inoculation suspension, regardless of the water supply level, had a less notable positive effect on the processes of nodule formation and nitrogen fixation, and in some cases even led to a decrease in the investigated values for control plants. Thus, the study demonstrated that the use of germanium, cobalt and ferum nanocarboxylates as components of the bacterial suspension helped to increase the adaptation of the formed legume-rhizobial symbiotic systems to water stress, as evidenced by the maximum indexes of nodulation and molecular nitrogen fixation in the context of insufficient water supply and recovery of their level to optimal after the stress influence had ended. Based on the results, it was concluded that inoculation of seeds by the complex bacterial preparations made on the basis of Bradyrhizobium japonicum B1-20 with a content of germanium, cobalt and ferum nanocarboxylates in the concentration of 1:1000 can become one of the important means in soybean growing technologies of increasing the nitrogen-fixing potential and resistance of plants to insufficient water supply.

Background. Global soybean production is expected to double in the coming decades, driven by a request for animal feed to meet increasing meat consumption. Demand for locally produced food and feed is also increasing, making it interesting to explore the potential for soybean production in high-latitude regions. Scope. To present information on the potential for cultivating vegetable soybean, edamame, under cold-temperate conditions. Conclusions. For the successful establishment, sowing at low soil temperatures should be avoided. Commercial inoculants are effective, irrespective of soybean cultivar. There is no need to re-inoculate fields if the crop has been included in the crop rotation. Little nitrogen remains in the soil after harvest, resulting in a low risk of leaching but a need for nitrogen fertilisation of the following crop. Suitable vegetable soybean cultivars are available on the market and are preferred compared to cultivars intended for dry harvest. The cropping system needs to be improved, e.g. by moderating the microclimate by plastic tunnels, in order to secure harvest.

Understanding the beneficial plant–microbe interactions is becoming extremely critical for deploying microbes imparting plant fitness and achieving sustainability in agriculture. Diazotrophic bacteria have the unique ability to survive without external sources of nitrogen and simultaneously promote host plant growth, but the mechanisms of endophytic interaction in cereals and legumes have not been studied extensively. We have studied the early interaction of two diazotrophic bacteria, Gluconacetobacter diazotrophicus (GAB) and Bradyrhizobium japonicum (BRH), in 15-day-old seedlings of rice and soybean up to 120 h after inoculation (hai) under low-nitrogen medium. Root colonization of GAB in rice was higher than that of BRH, and BRH colonization was higher in soybean roots as observed from the scanning electron microscopy at 120 hai. Peroxidase enzyme was significantly higher at 24 hai but thereafter was reduced sharply in soybean and gradually in rice. The roots of rice and soybean inoculated with GAB and BRH harvested from five time points were pooled, and transcriptome analysis was executed along with control. Two pathways, “Plant pathogen interaction” and “MAPK signaling,” were specific to Rice-Gluconacetobacter (RG), whereas the pathways related to nitrogen metabolism and plant hormone signaling were specific to Rice-Bradyrhizobium (RB) in rice. Comparative transcriptome analysis of the root tissues revealed that several plant–diazotroph-specific differentially expressed genes (DEGs) and metabolic pathways of plant–diazotroph-specific transcripts, viz., chitinase, brassinosteroid, auxin, Myeloblastosis (MYB), nodulin, and nitrate transporter (NRT), were common in all plant–diazotroph combinations; three transcripts, viz., nitrate transport accessory protein (NAR), thaumatin, and thionin, were exclusive in rice and another three transcripts, viz., NAC (NAM: no apical meristem, ATAF: Arabidopsis thaliana activating factor, and CUC: cup-shaped cotyledon), ABA (abscisic acid), and ammonium transporter, were exclusive in soybean. Differential expression of these transcripts and reduction in pathogenesis-related (PR) protein expression show the early interaction. Based on the interaction, it can be inferred that the compatibility of rice and soybean is more with GAB and BRH, respectively. We propose that rice is unable to identify the diazotroph as a beneficial microorganism or a pathogen from an early response. So, it expressed the hypersensitivity-related transcripts along with PR proteins. The molecular mechanism of diazotrophic associations of GAB and BRH with rice vis-à-vis soybean will shed light on the basic understanding of host responses to beneficial microorganisms.

The soybean [Glycine max (L.) Merrill] relationship with the bacteria Bradyrhizobium japonicum is responsible for providing around 60% of the nitrogen (N) required for the crop and the remaining N comes from the soil or supplemental fertilization. To investigate if higher yields are possible, supplemental N studies and co-inoculation of Rhizobium with Azospirillum are necessary. This N rate (0, 30, 56, 112, 336 kg N ha−1) and inoculation study was conducted across eight environments in eastern North Dakota, USA, in 2021 and 2022. Also, the effect of supplemental N and co-inoculation on nodulation was evaluated. When N was applied at 112 kg N ha−1, nodulation was significantly inhibited. Co-inoculation increased the number of large nodules and the volume of nodules; however, the yield was not different from inoculation with B. japonicum. Nitrogen at 112 and 336 kg ha−1 increased grain yield, protein yield, and seed weight; however, the higher N rate decreased plant population. There were significant positive relationships between yield and protein content and seed weight, and negative relationships between oil and protein content, and yield and oil content. Based on a polynomial relationship, the highest yield (3711 kg ha−1) would be achieved at 273 kg N ha−1. The application of N resulted in a yield increase but using current prices may not be an economical choice. Additional research is necessary to verify if co-inoculation with efficient strains can improve biological N fixation.

Rhizobium is a Gram-negative bacterium, which dissolves minerals, produces growth hormones, promotes root growth, and protects plants from different soil-borne pathogens. In the present study, roots, stalks, and fresh weight of maize (Zea mays L.) were significantly increased after soaking in Bradyrhizobium japonicum compared with the control. Subsequently, transcriptome sequencing results of the whole maize plant soaked in B. japonicum showed that multiple growth and development-related genes were up-regulated more than 100-fold compared to the control. Furthermore, the abundance of plant growth promoting bacteria, such as Acidobacteria Subgroup_6 and Chloroflexi KD4-96, were increased significantly. On the contrary, the abundance of multiple pathogens, such as Curvularia, Fusarium and Mycocentrospora, were significantly decreased. Moreover, inoculation with B. japonicum could inhibit the infection of the pathogen Fusarium graminearum in maize. These results suggest that soaking seeds in B. japonicum may affect the expression of maize growth and development-related genes as the bacteria changes the soil microorganism community structure. These findings may help to expand the application of B. japonicum in crop production and provide new opportunities for food security.

The production of ethylene by soybeans symbiotic systems associated with different Bradyrhizobium strains during the treatment of seeds with fludioxanil (fungicide) and exposure to drought was studied. It was found that the intensity of ethylene release by soybean plants during pre-sowing fungicide seed treatment and insufficient water supply primarily depends on the genetic characteristics and symbiotic properties of the of Bradyrhizobium strain. It is shown that the treatment of soybean seeds with a fungicide does not significantly change the dynamics of ethylene production by soybean plants in symbiosis with different strains of Bradyrhizobium japonicum under drought conditions. This proves the possibility of using seed inoculation with active rhizobia strains in combination with fungicide treatment for soybean cultivation in arid conditions. [ABSTRACT FROM AUTHOR]

The strategic task of soybean (Glycine max (L.) Merr.) breeding today is to create highly adaptive cultivars that have a high level of genetic protection from biotic and abiotic environmental factors and are able to maximise the yield potential in combination with a high grain quality. The use of inoculants is an environmentally safe measure that can significantly increase the soybean yield and reduce the level of plant damage by pests. The aim of the experiment was to evaluate the biological inoculants based on Bradyrhizobium japonicum strains under different cultivation conditions and dry-resistant soybean cultivars 'Almaz' and 'Antracite'. B. japonicum strains 634b for the 'Almaz' were the most effective in the Forest-steppe, as the yield increased by 0.11 t ha-1 compared to that of the control treatment. At the same time, the yield increased by 0.05 t ha-1 due to the application of B. japonicum strains M8. Under these cultivation conditions, for the 'Antracite', the B. japonicum strains M8 provided the greatest growth of yield (increased by 0.23 t ha-1 compared to that of the control) and by 0.14 t ha-1 when the B. japonicum strains 634b were used. On the average, over the experimental years, soybean cultivars in the Foreststeppe had a much higher yield (2.70-2.88 t ha-1) compared to that of the Steppe (1.28-1.88 t ha-1). Treatment with the B. japonicum strains 634b significantly increased the yield for the 'Almaz' and 'Antracite' in the Steppe. In the Forest-steppe, the treatment with B. japonicum strains 634b was more effective for the 'Almaz' and the one with B. japonicum strains M8 for the 'Antracite'. Quantitative symbiotic indices of soybeans were higher in the treatment with B. japonicum strains 634b for the 'Almaz' in the Forest-steppe and Steppe. In the Steppe, the application of B. japonicum strains M8 was more effective for the 'Antracite'. [ABSTRACT FROM AUTHOR]

There are a number of questions that have remained relevant for a long time when using inoculants based on nodule bacteria. It has been shown that exopolysaccharides (EPS) producing bacterial cells play one of the key roles during interaction and during signal transmission in legume-rhizobial symbiosis, namely, bacterial survival, virulence of rhizobia, shelf life on inoculated seeds and in soil, and efficiency created legume-rhizobial system. In particular, it was found that new strains of soybean nodule bacteria Bradyrhizobium japonicum LG 2 and LG 5 synthesize EPS at 3.2 and 2.8 g/l, with an optical density above 0.8 rel. units, the viscosity of the culture liquid - within 270-302 mPa • s. The high level of synthesis and the chemical composition of EPS of the studied strains ensured the preservation of the viability of bacterial cells on the surface of seeds and on a solid medium. Inoculation of soybean seeds with a culture liquid containing EPS of strains LG 2 and LG 5 ensured the formation of an effective legume-rhizobial system, which is confirmed by the formation of 18-21 nodules / plant of soybeans with a nitrogenase activity of at least 2.9 µmol C2H4 / plant per hour. A graph model has been developed, which proves the direct dependence of the effect of EPS on the number of nodules formed on the roots, the level of nitrogenase activity of the legume-rhizobial system and their indirect effect on the yield and protein content in soybean grain. Prospects isolated by strains LG 2 and LG 5 of B. japonicum for biotechnological production of liquid and gel biopreparations. [ABSTRACT FROM AUTHOR]

The aim of work was to investigate the influence of seed treatment with two preparations of fungicidal action, differing in the active substances composition, on the formation and functioning of legume-rhizobial symbiosis in interaction with the photosynthetic apparatus of soybean plants. It was established that in plants treated with preparation Fever, the nitrogen-fixing activity (NFA) difference with the control was insignificant, but under the impact of the preparation Standak Top NFA was by 63% less at the stage of three true leaves, by 48% -- at the stage of budding, and by 34% -- at the stage of budding--flowering. The net photosynthetic rate, calculated per leaf area unit, was lower than control at all investigated stages of soybean plants development in the variants with the seed protectants applying. A fairly close positive correlations (R² = 0.79) were observed between the average weight of one nodule and its NFA, and between the last and total NFA of the whole plant (R² = 0.78). Close correlations between plant NFA, chlorophyll content in leaves, and net photosynthetic rate were revealed. It was concluded that seed protectants significantly influenced on nitrogen fixation and photosynthesis. The strength of manifestation, and the sign of this influence in comparison with the relevant parameters of the control plants depended on the preparation, the stage of plant development, as well as on the index (nodules formation, nitrogen-fixing activity, photosynthetic, chlorophyll content, chlorophyll index, biological productivity of soybean plants) under consideration. [ABSTRACT FROM AUTHOR]