Aug 2026· Microbiology Research· Vol 313, pp.
128679
· 0 citations· 75 references
Medicine
TL;DR
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.
Abstract
Soil salinity severely constrains agricultural productivity worldwide, particularly affecting salt-sensitive crops such as maize (Zea mays L.) at early developmental stages. Plant growth-promoting rhizobacteria (PGPR) have emerged as a promising strategy to mitigate salinity stress; however, the underlying molecular mechanisms remain incompletely understood. In this study, we identified a salinity stress tolerance-promoting (SSTP) strain, Bacillus cereus isolate 74 (originally isolated from a salt-marshland environment), and investigated its role in enhancing salt tolerance in maize through integrated physiological and transcriptomic analyses. Phenotypic screening revealed that SSTP inoculation significantly improved plant growth parameters, chlorophyll content, and ionic balance under salinity stress. To elucidate the molecular basis of this response, RNA sequencing of maize roots was performed, identifying 307 high-confidence differentially expressed genes (DEGs). Functional enrichment analysis demonstrated that SSTP inoculation predominantly modulated pathways associated with oxidative stress mitigation, metabolic and catabolic processes, and cellular responses to chemical stimuli. Notably, genes involved in hydrogen peroxide detoxification, transport activity, and stress-responsive transcriptional regulation were significantly upregulated. These findings indicate that B. cereus isolate 74 enhances maize salt tolerance through coordinated regulation of antioxidant defense systems and metabolic reprogramming. This study provides novel insights into PGPR-mediated stress adaptation and highlights the potential application of SSTP strains in sustainable agriculture under saline conditions.
Results demonstrate that the HPGPB consortium enhances salinity tolerance through coordinated physiological, biochemical, and microbiome-associated mechanisms, highlighting 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
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.
Silvia Martínez-Fenoll, Adrián González Ortega-Villaizán, E. Rodríguez-Dobreva et al.· International Journal of Mol...· 0 citations
It was demonstrated that cucumber roots absorbed IAA production by Bacillus subtilis B21, thereby activating the expression of IAA signalling and ROS detoxification that had been inhibited by salt stress, providing new mechanistic insights into PGPR-mediated plant salt tolerance.
Jia-Wei Song, Yi-Jing Tian, Yu Song et al.· Plant, Cell and Environment· 0 citations
Drought stress is among the most critical limitations to maize productivity, particularly under rainfed conditions. In this study, we explored the Brazilian Caatinga biome as a source of drought adapted plant growth-promoting bacteria and evaluated their potential to mitigate drought effects in maize (Zea mays L.). A total of 414 thermo-tolerant bacterial strains were isolated from soil, of which 28 Bacillus strains were able to grow under low water activity. These strains exhibited multiple plant growth-promoting traits in vitro, including exopolysaccharide production, biofilm formation, siderophore production, indole-3-acetic acid synthesis, putative nitrogen fixation, and phosphate solubilization. Twelve selected strains significantly improved root morphology, relative chlorophyll content (SPAD units), and biomass accumulation in maize seedlings under osmotic stress induced by polyethylene glycol. Notably, strain 1A11 showed the most consistent effects, promoting root growth and biomass accumulation under both stressed and non-stressed conditions, indicating constitutive growth promotion across environments, whereas other strains showed stronger responses under stress. This stability across environments strengthens its agronomic value, particularly in regions characterized by high rainfall variability. Genome sequencing of five elite strains (1A11, 5D5, 6E9, 1H10, and 2E7) identified conserved gene clusters associated with exopolysaccharide production, indole-3-acetic acid synthesis, phosphate metabolism, iron acquisition (siderophore synthesis), synthesis of volatile compounds, motility, chemotaxis, and general responses to osmotic and oxidative stress. Multi-location field trials conducted across five locations in Brazil, under rainfed conditions, indicate that strains 1A11 (Bacillus subtilis), 5D5, and 6E9 (Bacillus velezensis) consistently increased grain yield compared to the non-inoculated control and performed similarly to or better than a commercial inoculant. Mean productivity gains with the strain 1A11 reached up to 39% relative to the non-inoculated treatment across environments. These results indicate that Bacillus strains isolated from semi-arid soils were able to convert multifunctional potential into measurable agronomic gains under field conditions, demonstrating their potential as bioinoculants to enhance maize resilience under water-limited agricultural systems.
U. G. de Paula Lana, S. D. de Sousa, B. T. V. Godinho et al.· Frontiers in Plant Science· 0 citations
Although SIRJ8 exhibited multiple plant-beneficial traits, its virulence-associated genomic repertoire precludes its consideration as an agricultural bioinoculant at present and underscores the necessity of comprehensive biosafety evaluation before any practical application.
S. Mukharjee, M. Hasan, B. Sikdar· Scientific Reports· 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.
