Nitric oxide (NO) is a small-sized, short-lived, highly diffusible, gaseous,
and bioactive molecule that regulates various physiological and pathological processes
in plants. It also plays a role in development, germination, flowering, senescence as
well as response to abiotic stress in plants. In recent years, the role of NO in tolerance
of abiotic stress posed by salinity, drought, heat, cold, UV-B, and heavy metals in
plants has been identified and gained importance in the field of plant research. Salinity
stress triggers the production of reactive oxygen species (ROS) that leads to oxidative
stress in plants, resulting in cellular destruction via lipid peroxidation, enzyme
inactivation, and DNA damage. To combat this stress and to minimize its harmful
effects, certain plants activate various ROS-scavenging enzyme activities. The role of
exogenous NO, which acts as an indicator in triggering ROS scavenging enzyme
activities and regulates antioxidant activities in plants to alleviate the toxic effects of
salt stress, has been well established. NO has been considered to play a key role in
reducing the excessive production of ROS in cells, improving secondary defense
mechanisms, alleviating osmotic damage, and maintaining cell permeability. Thus,
understanding the mechanisms of action of NO that help in effectively utilizing the
crop cultivation under saline conditions and support better growth of the plants is the
need of an hour. Considering this, the present review focuses upon the recent
knowledge of the crucial role of NO in providing tolerance to plants under salt stress.
Keywords: Antioxidant enzymes, Abiotic stress, Hydrogen peroxide, Nitric
oxide, Oxidative stress, Reactive oxygen species, Salinity, Sodium nitroprusside.
