Bacillus subtilis B21-Mediated Salt Tolerance in Cucumber via Auxin Signalling Activation.

Habitat-Adapted Fungal Symbionts Promote Salt Stress Tolerance Through Distinct Root Mechanisms and Shared Shoot Regulatory Networks in Arabidopsis thaliana

Salinity is a major constraint to crop productivity. Beneficial plant–fungus interactions represent a promising strategy to enhance stress resilience. Here, we investigated fungal endophytes isolated from the roots of Oryza sativa cultivated in saline-prone marshlands of the Guadalquivir River, Spain. From a collection of 38 isolates, five salt-tolerant strains exhibiting plant growth-promoting activity were identified, including a previously uncharacterized Reticulascus sp. strain S5. Co-cultivation assays with the non-native host plant Arabidopsis thaliana demonstrated that S5 increased the root and shoot biomass under salt stress. To elucidate the underlying molecular mechanisms, a comprehensive RNA-Seq analysis of the roots and shoots under control and saline conditions was performed. Fungal colonization induced pronounced transcriptomic changes, particularly in the shoots, including rewiring of the auxin- and abscisic acid-related pathways and the induction of genes associated with cell wall remodeling. Concurrently, defense-related processes, including glucosinolate biosynthesis and ethylene signaling, were broadly repressed, suggesting attenuated stress perception in colonized plants. In the roots, S5 inoculation suppressed the expression of genes involved in root hair development and cell wall organization, indicating a fungus-driven reconfiguration of root development. Moreover, comparative analysis with Fusarium sp. K-23, a fungus that has previously been demonstrated to promote plant growth under salinity stress, revealed distinct root-associated mechanisms but convergence on a shared regulatory module in shoots involving ABA-responsive transcription factors and osmotic stress regulators. Collectively, our findings demonstrate that Reticulascus sp. S5 enhances plant salt stress tolerance through the coordinated transcriptional reprogramming of growth, hormone signaling, and stress responses, highlighting a possible potential of habitat-adapted endophytes for sustainable crop improvement.

A halotolerant strain of Bacillus cereus effectively regulates salt stress-responsive genes in Zea mays L. seedlings under stress condition.

Findings indicate that B. cereus isolate 74 enhances maize salt tolerance through coordinated regulation of antioxidant defense systems and metabolic reprogramming, which provides novel insights into PGPR-mediated stress adaptation.

Rhizobacteria-Mediated Reprogramming of Phytohormone Landscapes for Mitigating Salinity Stress in Plants

Salinity stress is one of the major stressors that limits yield potential in field crops. Salinity-led imbalances in ionic and water potential, as well as oxidative damage, impair photosynthesis. Plant-growth-promoting rhizobacteria (PGPRs) have been demonstrated to mitigate salinity-stress-induced damage through various mechanisms such as biofilm and exopolysaccharide production, modulation of plant root architecture or molecular signaling involving modulation of sodium/potassium efflux transporters. PGPRs are known to induce biosynthesis and signaling of various phytohormones in plants. PGPR-derived phytohormones can in turn regulate molecular signaling involved in maintaining ion fluxes, preventing salinity-induced senescence, and reinforcing plant root architecture, thereby maintaining plant growth and development under saline conditions. In this review, we provide comprehensive advances on how PGPRs modulate and integrate biosynthesis and/or signaling of various phytohormones, such as auxins, cytokinins, gibberellin, ethylene, abscisic acid, salicylic acid, jasmonates, brassinosteroids and strigolactones, to reshape plant architecture, physiological and biochemical responses in plants under salinity. We integrate molecular evidence with morpho-physiological studies and propose a phytohormone-centric framework to select strains that optimize growth, ion homeostasis and plant stress resilience under salinity.

Brassinosteroid regulates thermotolerance through affecting the antioxidant capacity and the auxin pathway under heat stress in Brassica rapa ssp. pekinensis.

Heat stress threatens the yield and quality of plants. Brassinosteroid (BR) is widely used in agricultural production and plays important roles in regulating plant growth and stress response, but it is rarely reported on its function in thermotolerance in Chinese cabbage. In this study, we found that BR improves thermotolerance by alleviating the inhibition of leaf growth, and the BR biosynthesis inhibitor brassinazole (BRZ) treatment significantly reduced thermotolerance and plant growth in Chinese cabbage. Under heat stress, the accumulation of malondialdehyde and H2O2 was inhibited, and antioxidant-related enzyme activities and the contents of soluble protein and free proline were increased under BR treatment. Multiple transcriptome assays showed that BR may affect the expression levels of some BrSAUR genes in the auxin pathway, and ABA biosynthesis and metabolism genes to improve heat tolerance. Dual-luciferase reporter assay and VIGS assay showed that BrBZR1 can activate BrSAUR9 expression and the BrSAUR9-silenced plants inhibit plant growth. Furthermore, BR alleviated photosynthetic system damage and increased the fresh weight under heat stress. Our results provide new insights about the function of BR in conferring thermotolerance and biomass increase under heat stress in Chinese cabbage.

Rhizobial Symbiosis Enhances Salinity Tolerance in Legumes Through Coordinated Physiological and Molecular Responses: Evidence From Common Vetch and Pea.

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.

Microbial inoculation enhances salt tolerance by modulating secondary metabolites and key biosynthetic genes in Melissa officinalis