Review on Physiological and Phytochemical Responses of Medicinal Plants to Salinity Stress

Salinity is one of the most severe abiotic stresses that affects plant growth in many parts of the world. One of the major stresses that limits the growth and yield of crops is considered by affecting several important plant mechanisms such as water relations, photosynthesis, and enzyme activity and may impart specific ion toxicities to plants. Plants under stress of salinity produce of a variety of reactive oxygen species that cause oxidative damage to lipids, proteins, and nucleic acids. Various antioxidant compounds in plants sweep reactive oxygen species and include ascorbate, glutathione, alpha tocopherol, carotenoids, and antioxidant enzymes including superoxide dismutase, catalase, and peroxidase. Due to the effect of salinity stress in medicinal plants, the concentration of essential oil in most medicinal plants increases. The physiology of plant response to salinity and its relationship with salinity resistance in different plants has been studied. Nevertheless, there are no comprehensive studies or thorough review of salinity stress in medicinal and aromatic plants. Thus, the current review was conducted to discuss the formation of secondary metabolites and physiological responses in these plants under salinity stress.