Rhizobial Symbiosis Enhances Salinity Tolerance in Legumes Through Coordinated Physiological and Molecular Responses: Evidence From Common Vetch and Pea.
Aug 2026· Plant, Cell and Environment· 0 citations· 56 references
Medicine
TL;DR
Findings highlight the potential of Rhizobium inoculation to enhance crop resilience in salt-affected agroecosystems and demonstrate that symbiosis correlates with a more efficient and physiologically moderated acclimation to salinity in legumes.
Abstract
Soil salinisation severely constrains crop production. Legumes rely on rhizobial symbiosis for sustainable nitrogen acquisition. Although salinity is known to impair nodulation and nitrogen fixation, how symbiosis influences plant tolerance to salt stress remains unclear. In this study, we integrate physiological, biochemical, transcriptomic, ionomic, and metabolomic analyses to investigate the role of rhizobial symbiosis in salinity tolerance in Vicia sativa (common vetch) and Pisum sativum (pea). In both species, nodulated plants exhibited markedly enhanced survival and grain production under prolonged salt stress compared with nitrogen-fertilised (N-fed) controls. Under moderate salinity, nodulation helped maintain water status and stomatal conductance, reduced Na+ accumulation while improving K+ retention, and attenuated osmotic and oxidative stress, as evidenced by lower proline and malondialdehyde levels. Transcriptomic profiles in vetch revealed that symbiosis is associated with changes in the plant responses toward growth and microbial signalling, reducing the strong activation of stress pathways that typically occurs in non-nodulated plants. Ionomic and metabolomic data further showed that nodulated plants preserve nutrient balance and maintain a more stable carbon-nitrogen metabolism under salinity. These findings highlight the potential of Rhizobium inoculation to enhance crop resilience in salt-affected agroecosystems and demonstrate that symbiosis correlates with a more efficient and physiologically moderated acclimation to salinity in legumes.
This review critically examines the current knowledge on the functional roles of arbuscular mycorrhizal fungi and plant growth-promoting rhizobacteria in pistachio production and identified the key knowledge gaps and research priorities required to improve the consistency, scalability, and field validation of microbiome-based approaches for sustainable pistachio production under increasingly challenging environmental conditions.
L. Vera, Jorge Retamal-Salgado, G. Tortella et al.· Plants· 0 citations
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.
Soil salinity is a major abiotic stress that severely restricts crop productivity by disrupting ionic balance, inducing osmotic stress, and promoting oxidative damage. Black gram (Vigna mungo L.), an important pulse crop, is highly sensitive to salinity, resulting in reduced growth, physiological performance, and yield. The present study evaluated the efficacy of a compatible multi-strain HPGPB consortium comprising MKM3 (Halobacillus marinus), MKM4 (Halobacillus halophilus), and MKM11 (Halobacillus halophilus) in enhancing salinity tolerance in two black gram varieties (VBN8 and VBN11) under greenhouse conditions. Plants were subjected to 50 and 100 mM NaCl stress, with and without consortium inoculation, in a completely randomized design. Salinity stress significantly reduced plant growth, photosynthetic pigments, biomass, nutrient uptake, and grain yield, while increasing Na+ accumulation, lipid peroxidation, and osmotic stress markers. Consortium inoculation effectively mitigated these adverse effects by improving plant height, root development, biomass, and grain yield by up to 46 and 38%, respectively, under saline conditions. Consortium-inoculated plants exhibited improved photosynthetic performance, enhanced nutrient uptake and ionic balance, reduced Na+ accumulation and malondialdehyde content, and increased activities of antioxidant enzymes, indicating enhanced salinity tolerance. Among the tested varieties, VBN11 exhibited greater salinity tolerance and a stronger response to consortium inoculation than VBN8. Rhizosphere metagenomic analysis revealed consortium-associated shifts in microbial community structure under saline conditions. Collectively, the results demonstrate that the HPGPB consortium enhances salinity tolerance through coordinated physiological, biochemical, and microbiome-associated mechanisms. These findings highlight the potential of HPGPB consortia as sustainable bioinoculants for improving black gram productivity in salt-affected agroecosystems.
Daniel Raphael, Theivasigamani Parthasarathi· Frontiers in Microbiology· 0 citations
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.
Jie Bai, Tuo Yao, Wenbo Xu et al.· Agronomy· 0 citations
Climate change and increasing drought conditions significantly impede citrus productivity in subtropical and tropical regions. This study explores the potential of combining arbuscular mycorrhizal fungi (AMF) Funneliformis mosseae and plant growth-promoting rhizobacteria (PGPR) Pseudomonas putida to enhance drought tolerance in Citrus reticulata (Red tangerine). Although AMF-mediated drought tolerance has been extensively documented, the interactive effect of PGPR and AMF on phytohormone signalling, photosynthetic efficiency, nutrient acquisition, and gene expression remains largely unexplored in citrus. An experiment was conducted under well-watered and drought conditions to assess the physiological and molecular responses to individual and co-inoculation with PGPR and AMF. Under drought condition, dual inoculated plants showed significantly improved leaf water potential, stomatal conductance, carbon assimilation and antioxidant defence. PGPR-AMF co-inoculation enhanced chlorophyll stability, osmotic adjustment and nutrient uptake, while significantly reducing lipid peroxidation and ROS accumulation. The turquoise module emerged from transcriptomic and gene co-expression network analysis (WGCNA) as a potential key regulator of stress adaptation, revealing key regulatory transcription factors (e.g., CrMYB4, CrZFP8, CrSOS5, CrRGFR2 and CrQUA1) upregulated under combined inoculation, highlighting their potential role in stress adaptation. Our findings demonstrate that the synergistic PGPR-AMF interaction improves antioxidant enzyme activities and modulates gene expression to promote drought tolerance, providing new insights into the microbiome's role in plant resilience. These results offer a potential strategy to boost citrus growth and yield under water scarcity, with broad implications for agricultural resilience to climate change.
Saleem Uddin, Sadia Gull, Jie Wang et al.· Physiologia Plantarum : An I...· 0 citations
The potential of SZ01 as a microbial inoculant to promote plant growth and productivity in saline–alkaline environments, with implications for both medicinal and agricultural crop production, is highlighted.
