Role of secondary metabolites in salt and heavy metal stress mitigation by halophytic plants: An overview

Halophytic plants are known to be capable to adapt themselves to harsh conditions such as high salt and inorganic ion concentration (heavy metals), xerothermic atmosphere, improper irrigation, and cold seasonal temperatures. To mitigate the hazardous effects of heavy metals and saline environment, halophytic plants have evolved biological detoxification mechanisms in terms of avoidance or exclusion, evacuation, and accumulation of toxic ions. Halophytes restrain the toxic effects of high ion concentration by regulating certain biochemical pathways and physiological modifications. These detoxification mechanisms shield the plants against the production of reactive oxygen species (ROS) and free radicals and protect them from biomolecular damage. One of the most important defense mechanisms includes production of antioxidants. This chapter explores the detoxification mechanism of halophytic plant system for salt and heavy metal stress by their inherent potential to accumulate certain nonenzymatic antioxidants such as secondary metabolites and to absorb and safely handle toxic ions.