Cellular Responses, Osmotic Adjustments, and Role of Osmolytes in Providing Salt Stress Resilience in Higher Plants: Polyamines and Nitric Oxide Crosstalk

Salinity stress is a chief abiotic hindrance affecting crop productivity and yield particularly in arid and semi-arid regions across the globe. Plants have evolved a network of physiological and molecular mechanisms to cope with salinity stress. The complex and multi-faceted nature of salinity tolerance involve several mechanisms and a comprehensive approach on how plants employ tolerance to salinity at distinct levels and combining physiological measurements with new molecular technologies is an emerging area of crop research. Recent evidences from salinity tolerance mechanisms highlight osmolytes that play a key role in quenching free radicals, induce antioxidant machinery, and osmotic regulation. Polyamines (PAs) also exhibit a promising role in salt tolerance mechanism and adaptation strategies mainly by stabilization of membranes, neutralization of acids, and suppressing ROS synthesis. Interconnection of PAs and nitric oxide biosynthesis also raise hopes for better tolerance to plants under stressful environment. Based on recent findings, the present review highlights the protective role of ion pumps, osmolytes, and polyamines during salt stress. All these strategies have emerged as potential targets for researchers to confer salt stress tolerance in plants.