Mitigation of salt stress in wheat plant (Triticum aestivum) by ACC deaminase bacterium Enterobacter sp SBP-6 isolated from Sorghum bicolor

The plant growth promoting bacteria can ameliorate the abiotic stressors through induced systemic tolerance in associated plants. The present work reports the efficiency of a plant growth promoting rhizobacterium (PGPR) Enterobacter sp. SBP-6 containing ACCD activity to stimulate the growth of the wheat plant under salinity stress conditions. Besides ACCD activity, the isolate was able to show other plant growth promoting (PGP) traits like phosphate solubilization, phytohormone production, nitrogen fixation, etc. The application of isolate SBP-6 to the wheat plants alleviated the inhibitory effects of gradient levels of salinity (150, 175, 200 mM NaCl) on various parameters of plant growth and photosynthetic pigments. Results of pot experiments revealed that inoculation with the test isolate significantly increased the plant biomass by 10-42 % as compared to their respective uninoculated control. An ability of the isolate to alleviate the effect of salt stress was also evident by significant increase of chlorophyll content (33-41 %), reduction in toxic Na+ ionic content (19-41 %), increase in K+ uptake (23-31 %), thereby favoring the K+/Na+ ratio and a significant decrease in leaf proline and malondialdehyde content in bacteria-treated plants exposed to salt stress. These results indicated that the selected isolate SBP-6 can be used for promoting the plant growth under salinity stress.