Inoculation with plant growth-promoting bacteria (PGPB) improves salt tolerance of maize seedling

Our objective was to evaluate the role of plant growth-promoting bacteria to protect maize (Zea mays L.) plants against salt damage. Bacillus aquimaris DY-3 based on their 16S rDNA sequences, the most tolerant to salinity and the synthesis of indole acetic acid was selected for further studies. Strain was inoculated on maize roots growing in sterilized sand under salt stress conditions (1% NaCl). After one week, plant growth was promoted by bacterial inoculation regardless of salt stress and non-salt stress. Chlorophyll content, leaf relative water content, accumulation of proline, soluble sugar and total phenolic compound, and activities of superoxide dismutase, catalase, peroxidase and ascorbate peroxidase were enhanced, while lipid peroxidation levels and Na⁺ content were decreased. The results showed that B. aquimaris DY-3 alleviated the salt stress in maize, likely through the integration of the antioxidant enzymes and the non-antioxidant systems that improve the plant response. Hence, the application of indole acetic acid synthesizing plant growth-promoting bacteria may represent an important alternative approach to decrease the impact of salt stress on crops.