Salinity intrusion and coastal agriculture: adaptation strategies using salt-tolerant plant-growth promoting rhizobacteria for sustainable food security

Аннотация

The salinity level in the coastal ecosystem and agricultural lands is being increased gradually due to the climate change effect, and Bangladesh is no exception to suffer salinity intrusion threatening its food security. In order to bring the salinity-affected lands under agriculture, the application of salt-tolerant, plant growth-promoting rhizobacteria (PGPR) as biofertilizer could be a method of choice. The current research reports the isolation of a salt-tolerant PGPR, identifi ed as Bacillus aryabhattai MS3 from a coastal rice fi eld of Bangladesh. Under laboratory condition, the strain showed profound plant growth-promoting activities: nitrogen fi xation, production of indole acetic acid (IAA), phosphorus solubilization and siderophore production under 200 mM salinity. While in soil, rice growth under non-saline condition was comparable in between biofertilizer-added and control pots, the scenario was statistically signifi cant when challenged with salts, 46% and 8% survival were recorded respectively. The PGPR supported the plants under salinity by increasing the availability of nutrients, accelerating IAA and chlorophyll production, enhancing proline accumulation, and decreasing malondialdehyde formation. The semi-quantitative reverse transcription-PCR demonstrated that the bacterium selectively up-regulated the plant expression of NHX1 gene under salinity, thereby conferring tolerance to salt stress. Overall, the application of salt-tolerant biofertilizer could be a non-transgenic innovation to support plant growth for coastal lands under changing climate conditions.