Search Results (540)

The present study aimed to evaluate the biocontrol and plant growth-promoting potential of putative nitrogen-fixing bacterial strains isolated from the soils of Northern Kazakhstan against major cereal crop phytopathogens and during the early stages of plant development. Phytopathogenic fungi, Fusarium proliferatum and Alternaria alternata, were isolated from infected cereal tissues and seeds using conventional mycological techniques. The antagonistic activity of the bacterial strains was assessed using a dual-culture assay. A total of 26 bacterial isolates were screened for antagonistic activity and plant growth-promoting effects. Several isolates exhibited pronounced inhibitory activity against both pathogens by suppressing fungal mycelial growth. The plant growth-promoting potential of bacterial culture filtrates was evaluated under in vitro conditions using buckwheat (Fagopyrum esculentum Moench) varieties ‘Shortandinskaya 6’ and ‘Shortandinskaya Krupnozernaya’. Germination energy, laboratory germination, shoot length, and root length were recorded during seedling development. The tested bacterial culture filtrates showed a stimulatory effect on seedling growth, with the most pronounced response observed in root elongation, indicating their positive influence on rhizogenesis. The obtained results demonstrate that Agrobacterium pusense st.51S, Ensifer fredii st.59S, and Oricola cellulosilytica st.70S exhibited strong antagonistic activity against Fusarium proliferatum, whereas O. cellulosilytica st.70S, Streptomyces virginiae st.11S, and Ensifer meliloti st.56S effectively inhibited the growth of Alternaria alternata. In addition, E. meliloti st.56S, Priestia megaterium st.35S, Rhizobium giardinii st.2S, and Ensifer sp. st.91S significantly promoted buckwheat seed germination and seedling growth. The most pronounced growth-promoting effect was observed for E. meliloti st.56S, which increased shoot and root length of ‘Shortandinskaya 6’ by 31.4% and 23.8%, respectively, compared with the control. These strains represent promising candidates for the development of microbial bioformulations aimed at improving seed quality, enhancing early plant development, and promoting sustainable crop production under the dry steppe conditions of Northern Kazakhstan. Full article

Soybean (Glycine max) is a globally important source of protein and oil, and its capacity for biological nitrogen fixation (BNF) underpins its strategic role in sustainable agriculture. However, BNF efficiency is highly sensitive to abiotic stresses, and conventional agronomic interventions struggle to simultaneously optimize nodulation, nitrogenase activity, and stress resilience. Agricultural nanotechnology offers a unique avenue to address this bottleneck by modulating the tripartite nanomaterial–rhizobium–soybean interaction at multiple scales. This review systematically examines (1) nanomaterial design strategies tailored to the rhizosphere and nodule microenvironments; (2) the ‘Rhizosphere–Nodule–System’ (RNS) cascade model, which integrates rhizosphere interfacial events, nodule metabolic reprogramming, and systemic stress signaling; and (3) field-level efficacy, genotype-dependent responses, and barriers to scalable application. By elucidating the mechanistic logic by which nanotechnology coordinates BNF enhancement with abiotic stress tolerance, this framework provides theoretical support for the targeted deployment of nano-agricultural technologies in soybean production systems. Full article

Microplastic pollution severely threatens aquatic ecosystems, yet the trophic microecological risks of petroleum-based polyvinyl chloride (PVC) and biodegradable polyhydroxyalkanoate (PHA) microplastics remain insufficiently compared. This study established a two-trophic food chain model with Daphnia magna and zebrafish to explore the toxic effects and microbial disturbances of environmentally relevant 0.1 mg/L PVC and PHA. A 21-day chronic exposure induced no physiological damage to the survival, growth, reproduction, and locomotion of both organisms, suggesting conventional phenotypic indicators fail to identify early microplastic stress. However, trophic microplastic exposure triggered prominent zebrafish gut dysbiosis with distinct pathogen enrichment patterns. PHA trophic exposure enriched plant pathogenic genera (Acidovorax, Clavibacter, Rhizobium), whereas PVC trophic exposure accumulated zoonotic and clinical pathogens (Acinetobacter, Neisseria, Mycobacterium, Aeromonas). This work verifies that PHA is not entirely eco-safe, and PVC poses greater ecotoxicological risks via trophic pathogen transmission, providing genus-level evidence for differentiated microplastics risk assessment. Full article

Microbial inoculation has been unequivocally established as an effective strategy for promoting plant growth and enhancing salinity tolerance. The objective of this work was to examine the influence of AMF (Funneliformis mosseae) inoculation, whether applied singly or together with PGPR (Bacillus mycoides and Sinorhizobium meliloti), on osmotic balance, ionic homeostasis, soil nutrient status, and enzyme activities in salt-stressed alfalfa (Medicago sativa L.). The results showed that salt stress significantly inhibited soil enzyme activities, reduced soil nutrient contents, and significantly increased the contents of osmolytes and Na⁺ in both leaves and roots of alfalfa. Additionally, the accumulation of Na⁺ in roots and leaves exhibited a significant negative correlation with soil nutrient contents (NH₄⁺-N, NO₃⁻-N, available phosphorus and available potassium) as well as with soil enzyme activities (sucrase and alkaline phosphatase). However, microbial inoculation significantly alleviated these adverse effects, mainly by increasing osmotic adjustment substances (e.g., proline), enhancing soil enzyme activities (e.g., urease), improving soil nutrient contents (e.g., soil organic matter), and promoting the uptake of K⁺ and Ca²⁺, thereby raising the K⁺/Na⁺ and Ca²⁺/Na⁺ ratios. Comprehensive analysis revealed that the co-inoculation treatments were superior to the single inoculations, with T7 (AMF + Rhizobium) exhibiting the best performance. This study provides a theoretical reference for the application of microbial inoculants to improve alfalfa performance under saline–alkali conditions. Full article

Rhizogenic Agrobacterium (Rhizobium) spp. are causative agents of hairy root disease (HRD), a major threat to hydroponic crop production worldwide. The use of specific bacteriophages is considered a prospective approach to control the development of HRD in greenhouses. A combination of diverse bacteriophages is a key step to overcome potential phage resistance in the pathogen. In this study, a novel lytic bacteriophage, named Miki, was identified and characterized for its antibacterial potential against a rhizogenic Agrobacterium sp. strain circulating in greenhouses in Central Russia. High-throughput sequencing revealed a 63,458 bp double-stranded DNA genome (G + C content 53%), with 117 predicted coding sequences, considering Miki as a lytic candidate phage for plant protection. Electron microscopy of phage Miki shows a morphology unusual for Agrobacterium phages, and phylogenetic analysis attributes it as a representative of a previously undescribed taxon at least at the genus level. The paper presents a detailed analysis of the genome and structural proteome of phage Miki, including in silico predictions and modeling of receptor-binding proteins, including central and proximal fibers resembling the adsorption apparatus of Escherichia phage T5. Full article

Herpetospermum pedunculosum is an endangered cucurbitaceous medicinal plant whose functional genomic and metabolic studies are constrained by the lack of efficient aseptic seedling and genetic transformation systems. Here, we established a rapid aseptic seedling production method and a RUBY-assisted hairy root transformation platform integrated with metabolomic evaluation. The cotton-supported liquid culture method provided a favorable balance between germination performance and experimental operability. Microsyringe-mediated stem-base inoculation with Rhizobium rhizogenes K599 carrying 35S::RUBY enabled rapid visual screening of RUBY-positive hairy roots, with a maximum transformation efficiency of 93.33%. Widely targeted metabolomics identified 242 metabolites and revealed major differences in amino acid/nitrogen and sugar metabolism, lipid-related metabolism, specialized metabolite biosynthesis, hormone-related pathways, and ABC transporters among wild-type, vector-free K599-induced, and RUBY-expressing roots. In addition, 80 HpRHL-like bHLH genes were identified. As a proof of concept, RT-qPCR confirmed HpRHL76 overexpression, which was associated with an increase in mean root hair length from approximately 0.4 to 1.1 mm. Together, this integrated framework provides a practical basis for preliminary candidate gene assessment, functional genomic studies, and future metabolic engineering of medicinally relevant compounds in H. pedunculosum, and may serve as a methodological reference for other difficult-to-transform medicinal plants. Full article

Salt stress is a prevalent abiotic stress worldwide, which markedly inhibits crop growth and triggers yield losses. In this study, salt-tolerant plant-growth-promoting rhizobacteria of Cerasus humilis—Bacillus pumilus and B. velezensis, which possess nitrogen-fixing, phosphate-solubilizing, and indole-3-acetic acid (IAA) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase-producing traits—were co-inoculated with Sinorhizobium meliloti. The effects of these bacterial combinations on alfalfa (Medicago sativa L.) were systematically evaluated during seed germination and plant growth under salt stress simulated using NaCl, Na₂SO₄, NaHCO₃, and Na₂CO₃ at varying intensities. The results showed that under salt stress, inoculation significantly increased the seed germination rate by 11.33–41.33%. Pot experiments further revealed that inoculation significantly enhanced symbiotic nitrogen fixation efficiency in alfalfa and effectively maintained K⁺/Na⁺ homeostasis (K⁺ concentration increased by 4.23–125.34%, while Na⁺ concentration decreased by 7.15–102.09%). Concurrently, inoculation upregulated antioxidant enzyme activities and promoted the accumulation of non-enzymatic antioxidants, thereby significantly reducing reactive oxygen species levels. Moreover, inoculation substantially increased the content of osmoregulatory substances such as proline and soluble protein; proline accumulation surged more than fivefold (39.97–551.05%) compared with the non-inoculated control, effectively alleviating cellular dehydration. Through these multi-pathway regulations mediated by Bacillus sp. and S. meliloti, the inhibitory effect of salt stress on alfalfa growth was significantly mitigated, with dry weight increasing by 45.9–92.4%. Principal component analysis indicated that inoculation with the B. velezensis–S. meliloti microbial combination was the most promising strategy for promoting alfalfa growth and alleviating salt stress. The results provide a theoretical basis for developing microbial fertilizers and establishing alfalfa pastures in saline lands, thereby promoting their sustainable utilization. Full article

Replacing chemical compounds with biologically derived bioproducts in agriculture can make a comprehensive contribution to achieving the goals of both the Paris Agreement and the Green Deal. Scientific literature contains a significant amount of data on the use of probiotics in agriculture, which facilitate the supply of nutrients to plants, stimulate physiological processes, and inhibit the development of pathogens. These products do not have a negative impact on the surrounding environment and can therefore be used in sustainable land management. This article analyzes the microbiological composition of a bio-input made from fermented nettle extract and the species diversity of the cultivable bacteria. It was found that this input is rich in bacteria beneficial to plants and soil (Clostridium, Paenibacillus, Frankia, Rhizobium, Bradyrhizobium, Azospirillum, Azotobacter, and others), some of which can be cultured under artificial conditions. Among the cultivable bacteria grown from the tested input, the majority were representatives of the Pseudomonadota (92%), and a small proportion were Bacillota (6%). Among them were a great many different bacteria beneficial to the soil ecosystem. Thus, there is considerable potential here for the use of these bacteria in the production of biological products. Full article

Legume–rhizobium symbiosis is fundamental to sustainable agriculture because it supplies biologically fixed nitrogen, improves soil fertility, and reduces reliance on synthetic fertilizers. However, abiotic and chemical stresses, including drought, salinity, flooding, temperature extremes, heavy metals, and organic pollutants, disrupt nodulation and biological nitrogen fixation, limiting crop productivity and ecosystem sustainability. This review synthesizes current knowledge of the regulatory networks that enable legume–rhizobium symbiosis to adapt to environmental stress. We discuss how stress influences symbiotic signaling, infection, oxygen homeostasis, nitrogenase protection, phytohormonal regulation, antioxidant defenses, exopolysaccharide production, and plasmid-mediated adaptation. We further highlight the roles of root nodule-associated microorganisms and microbial interactions in maintaining symbiotic stability under adverse conditions. Finally, recent advances in multi-omics, genome editing, synthetic biology, and microbial consortia are evaluated for their potential to improve stress-resilient bioinoculants. Collectively, this review emphasizes that resilience of the legume–rhizobium symbiosis is an integrated property of both plant and microbes and identifies key regulatory mechanisms that can be exploited to develop climate-resilient and sustainable agricultural systems. Full article

Rho GTPase-activating proteins (RhoGAPs) are characterized by a conserved RhoGAP domain and function as negative regulators of Rho GTPases, playing important roles in plant growth, development, and responses to environmental stimuli. In this study, 19 GmRhoGAP genes were identified in the soybean genome and found to be unevenly distributed across 11 chromosomes. Comprehensive analyses were performed, including gene structure, conserved motifs, protein domains, gene duplication, synteny, cis-acting elements, tissue-specific expression, and quantitative real-time PCR under rhizobial infection. Structural analysis revealed substantial diversity in intron-exon organization but high conservation of motif composition, with all members containing the conserved RhoGAP domain. A total of 20 segmentally duplicated gene pairs were identified, indicating expansion of the GmRhoGAP family in soybean. Inter-species synteny analysis showed closer evolutionary relationships with Arabidopsis than with rice, and Ka/Ks analysis suggested strong purifying selection during evolution. Promoter analysis indicated potential involvement in development, phytohormone signaling, stress responses, and light responsiveness. Expression profiling demonstrated distinct tissue-specific patterns. qRT-PCR further showed that GmRhoGAP genes respond differentially to rhizobial infection, with 10 generally upregulated genes and 4 downregulated genes. These analyses provide a framework for understanding this gene family and identify candidate genes for future research. Full article

Innovation in plant-breeding technology relies on precise, targeted genetic manipulation, which depends on the efficient delivery of genetic elements and robust plant cell regeneration systems. Agrobacterium tumefaciens, a traditional medium for genetic material delivery, is well established and has become widely adopted, but it faces limitations such as species specificity, transformation chimerism, and the requirement for two-step processes of transformation and regeneration. In contrast, Rhizobium rhizogenes can deliver genetic material with efficiency comparable to that of A. tumefaciens while excelling in producing transgenic homozygotes in a single step. This article summarizes the molecular mechanisms underlying R. rhizogenes-mediated hairy-root induction in plants, discusses the development of genetic material delivery systems, details the construction of hairy-root induction and regeneration platforms, explores molecular mechanisms in hairy roots and their applications in genetic breeding, and highlights the use of hairy roots for extracting secondary metabolites. The hairy-root genetic transformation system provides efficient, simplified, and broadly adaptable tools for genetic manipulation in breeding, accelerating the advancement of cutting-edge technologies such as gene editing, rapid domestication, and synthetic biology-driven breeding. Full article

This study investigates nitrogen-fixing rhizobia associated with Pisum sativum, a member of the tribe Vicieae (Fabaceae), whose species establish symbioses with bacteria belonging predominantly to the symbiovar viciae within the Rhizobium leguminosarum complex (Rlc). Based on a comprehensive taxonomic revision of the F-clade within this complex, we report the identification and characterization of a novel rhizobial subspecies, Rhizobium laguerreae subsp. mediterraneum subsp. nov., isolated from pea nodules in Tunisia. Phylogenetic analyses based on 16S rRNA and multilocus sequence analysis (recA, atpD, dnaK, and glnII) placed strains 25PS6 and 10PS4 within the Rlc, while whole-genome phylogenomics using 2960 single-copy orthologues supported their assignment to a distinct monophyletic clade (Q-II). Subspecies-level clustering consistency was maximized using an optimized ANIm criterion of 97.40%, corresponding to 76.65% dDDH. Both strains belong to symbiovar viciae and exhibited improved symbiotic performance on pea plants compared to the reference strain, indicating strong symbiotic performance and potential relevance for biological nitrogen fixation. Cluster-specific SNP analysis identified 63 exclusive non-synonymous mutations with putative functional effects predicted in silico. These results suggest that cluster-specific nsSNPs may contribute to genomic differentiation within the Q-II lineage. Phenotypic and chemotaxonomic analyses further distinguished the novel subspecies based on carbon utilization, enzymatic activity, antibiotic resistance, and fatty acid profiles. Together, these findings highlight the genomic diversity within nitrogen-fixing rhizobia associated with legumes and identify a novel subspecies with potential agronomic relevance for improving symbiotic nitrogen fixation in pea cultivation. The proposed subspecies, Rhizobium laguerreae subsp. mediterraneum, is represented by strains 10PS4 and 25PS6, with strain 25PS6^T (=DSM 116212^T = LMG 33205^T) designated as the type strain. Full article

The growth of vegetable plants is dependent on numerous environmental factors, including the presence of rhizosphere bacteria that produce phytohormones and support mineral uptake. The aim of this study was to determine the effect of symbiotic bacteria belonging to the Rhizobium leguminosarum species and other PGPR bacteria: Bacillus cereus, Chryseobacterium lathyri, and Lysinibacillus fusiformis, on seed germination and plant growth of a few crop species (i.e., white cabbage, broccoli, red pepper, and sugar beet). Three inoculation variants were tested: a mixture of R. leguminosarum strains (R), a mixture of other PGPR bacteria (B), and a combination of both of them (R + B). Biometric parameters such as seed germination, seedling growth, and the length and weight of upper parts and roots were determined. Our results showed diverse responses of the studied crop species to the bacterial mixtures used. In the case of variants R and R + B, the strongest effect of inoculation on seed germination and plant growth was observed. The obtained results indicated the agricultural potential of the analyzed bacterial consortia as biological support for the production of vegetable crops. They also emphasize the need for further research on their effectiveness in various environmental conditions. Full article

To evaluate the ameliorative effects of different green manure crops on continuously cropped protected pepper soil and to identify suitable green manure species for plateau-protected cultivation systems, a one-factor randomized complete block design was conducted with five treatments: common vetch (L1), pea (L2), hairy vetch (L3), radish (L4), and a control without green manure (CK). Soil physicochemical properties, enzyme activities, and microbial community composition were determined at the full-bloom stage before green manure incorporation. Compared with CK, L1 reduced soil pH from 8.63 to 8.34 and decreased total salt content by 45.5%, increased alkali-hydrolyzable nitrogen by 40.93%, and significantly enhanced catalase activity. L3 increased available phosphorus by 23.72% and urease and sucrase activities by 71.32% and 56.31%, respectively, while significantly affecting fungal β-diversity and community composition. Community composition analysis showed that L3 increased the relative abundances of the bacterial genus Rhizobium and the fungal genus Rhizophagus, while reducing the relative abundance of Ascomycota and several potentially pathogen-associated fungal taxa. Redundancy analysis and Mantel tests indicated that bacterial community composition was mainly associated with soil total salt content, alkaline phosphatase, and available phosphorus, whereas fungal community composition was more closely related to urease and alkaline phosphatase. Random forest analysis and partial least squares path modeling further suggested that sucrase, urease, and catalase were important factors closely associated with changes in the soil quality index (SQI). Overall, common vetch performed better in reducing soil salinity, increasing alkali-hydrolyzable nitrogen, and improving the soil quality index and may therefore be considered a suitable green manure species for improving continuously cropped protected pepper soil on the Qinghai Plateau. Hairy vetch showed advantages in increasing available phosphorus and regulating fungal community composition, indicating its potential suitability for protected soils with limited phosphorus availability. Full article

Seed enhancement technologies have emerged as promising approaches to improve seedling growth and nursery performance of forest tree species. This study evaluated the effects of combining seed priming and seed coating technologies with beneficial microbial inoculants on the seedling quality of Falcataria falcata (L.) Greuter & R.Rankin. Fourteen treatments, including hydropriming (HP), gibberellic acid (GA₃), Rhizobium sp., Trichoderma sp., endomycorrhiza, polymer coating, nutrients, fungicide, and insecticide, were assessed under nursery conditions. Seedling quality was determined using the number of roots, number of nodules, root-to-shoot ratio, vigor index I, and vigor index II. Significant differences among treatments were observed for all measured parameters (p < 0.001). The treatment HP + GA₃ + Rhizobium sp. + polymer coat + fungicide (T13) produced the highest number of roots (31.76 roots seedling⁻¹), indicating enhanced root development. Meanwhile, HP + endomycorrhiza (T4) resulted in the highest number of nodules (5.49 nodules seedling⁻¹), root-to-shoot ratio (0.593), and vigor index I (2055.57), reflecting improved biomass allocation and overall seedling quality. Principal component analysis explained 71.9% of the total variation and revealed distinct associations between treatments and growth attributes. Treatments containing Rhizobium sp. were primarily associated with root proliferation and seedling vigor, whereas endomycorrhizal treatments were linked to nodulation and balanced biomass development. The results demonstrate that integrating microbial inoculants with seed priming and coating technologies can significantly enhance seedling quality, even when germination responses are similar among treatments. These findings highlight the potential of biologically enhanced seeds as a sustainable strategy for producing vigorous planting materials suitable for plantation forestry, reforestation, and landscape restoration programs. Full article