Plant growth promoting bacteria mitigates deleterious effect of salt stress in plants by physiochemical modulation

The utilization of plant growth promoting rhizosphere microorganisms (PGPR) offers an eco-friendly approach to alleviate salt stress. In the present study, various PGPR strains were isolated from the rhizosphere of Triticum aestivum under both normal and saline conditions. All the isolated strains were screened for their plant growth promoting potential and strain 16R and 17 showed the growth promoting effects. Moreover, stress reliance efficiency of strain 16R and 17 in response to various salinity levels (50, 100 and 150 mM NaCl) was further examined. The results revealed that soil salinization reduced plant growth, whereas plants inoculated with both strains showed significantly diminished adverse effects caused by salt stress up to 150 mM NaCl and showed improved plant growth. The growth attributes, shoot and root dry weights, root and shoot soluble sugars and protein were increased by inoculation with a saline-adapted isolate, especially at high NaCl levels. Inoculation with both bacterial isolates significantly decreased sodium accumulation in both shoots and root tissues. Moreover, the selected strain 17 isolated from T. aestivum grown under saline conditions was more effective than strain 16R in promoting plants and mitigating salinity stress. The selected strains, 16R and 17, were identified as Bacillus safensis based on molecular characterization.