Exploiting halotolerant endophytes to improve growth and salinity resilience of Catharanthus roseus (L.) G. Don

Bacillus from the Brazilian Caatinga biome enhances maize productivity and agronomic performance under rainfed conditions across multi-location field trials

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.

Halotolerant Kocuria and Bacillus species enhanced saline-alkaline stress tolerance in foxtail millet

Saline-alkaline stress is an increasing threat to agricultural productivity due to climate change and anthropogenic activities. Plant growth-promoting bacteria (PGPB) have emerged as a sustainable approach to enhance crop growth and stress tolerance under adverse environmental conditions. In this study, two halotolerant strains, Kocuria palustris Pp13 (Pp13) and Bacillus aryabhattai Pp16 (Pp16), isolated from the endosphere of Napier grass, were selected to analyze their stress tolerance mechanisms and evaluate their plant growth-promoting traits under saline-alkaline conditions. The stress tolerance and plant growth-promoting traits of Pp13 and Pp16 was evaluated under different salinity and pH conditions. The effects of bacterial inoculation on the growth and stress tolerance of foxtail millet ( Setaria italica L.) were assessed by analyzing plant growth, osmotic and oxidative stress responses, and ion accumulation under saline-alkaline conditions. Both Pp13 and Pp16 formed biofilms and accumulated proline under stress conditions, while their phosphorus-solubilizing activity was only slightly affected by elevated salinity and pH. Notably, Pp13 maintained IAA-like metabolite production and ACC deaminase activity under stress conditions. Inoculation with either strains significantly improved the growth and stress tolerance of foxtail millet under saline-alkaline conditions. Bacterial inoculation increased proline accumulation, elevated ascorbate peroxidase activity, improved photosynthetic performance, and reduced oxidative damage and sodium accumulation, resulting in greater biomass accumulation. These findings demonstrate that Pp13 and Pp16 possess multiple stress-adaptive and plant growth-promoting traits that contribute to improved crop performance under saline-alkaline conditions. The results highlight the potential of these strains as bioinoculants for sustainable crop production in saline-alkaline soils and identify Kocuria species as a relatively unexplored source of beneficial microorganisms for enhancing plant stress tolerance.

Seed biopriming with a novel endophytic Bacillus licheniformis strain RGS enhances drought tolerance and recovery in tomato

Endophytic Aspergillus fumigatus modulates growth, oxidative stress, and cadmium accumulation in okra under salinity and heavy-metal stress

It is shown that endophytic fungi have the potential to enhance plants’ resilience and provide a promising controlled-environment approach to enhance crop productivity in metal- and salt-contaminated soils.

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

Integrative functional profiling of rhizospheric and endophytic bacteria reveals Lelliottia aquatilis as a multifunctional PGPR in Himalayan ecosystems

This study introduces L. aquatilis strain MC3 as an emerging candidate for bioinoculant development and one of the first reports for identification of L. aquatilis as multifunctional PGPR from Himalayan ecosystems.