Identification of endophytes Bacillus velezensis AH216 and its effects on salt stress tolerance and growth in maize

Objective This study investigates the effects of a plant Bacillus velezensis AH216 on maize growth and soil nutrients under salt stress treatments.

Methods Bacillus velezensis AH216, isolated from the endophytic environment of cotton (Gossypium hirsutum L.), was selected for identification and measurement of plant growth-promoting related functions such as indole-3-acetic acid (IAA) synthesis. Pot experiments with maize were conducted under both normal soil and saline stress soil conditions to analyze the effects of inoculation of with AH216 on plant growth promotion and soil nutrients.

Results Strain AH216 was identified as Bacillus velezensis through 16S rRNA and whole-genome sequencing. The strain demonstrated the ability to solubilize potassium, produce protease and cellulase, as well as synthesize IAA and siderophore. In both normal and saline-stressed soils, inoculation with strain AH216 significantly promoted the growth of maize plants, with increases in total biomass, plant height, stem diameter, leaf width, leaf area, and chlorophyll content by 6.8% - 108.3%. Additionally, inoculation with strain AH216 improved soil physicochemical properties and enzyme activities, leading to increases in available phosphorus, soluble potassium, sucrase, and urease activity by 15.4%, 30.3%, 44.2%, and 35.8% in normal soil, and by 18.8% and 34.8%, 60.4%, and 59.4% in saline-stressed soil, respectively.

Conclusion The plant endophytic Bacillus velezensis AH216 significantly promotes the growth and development of maize, improves soil nutrients, and soil enzyme activity, and enhances the salt stress resistance of maize plants.