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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.

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]

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.

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., Competing Interests: The authors declare no conflict of interest., (© 2024 The Author(s). Published by IMR Press.)

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., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Chen, Sang, Chilvers, Wu and Chang.)