Roles of ascorbic acid on physiological, biochemical, and molecular system of Lycopersicon esculentum Mill. against salt stress

Tomato is an important plant grown for food and medicine, which is sensitive to abiotic stresses. On the other hand, ascorbic acid (AsA) is a compound used as the plants’ universal defense mechanism against stresses specially salinity and drought to scavenge reactive oxygen species. Due to global warming and subsequent scarcity of water resources, drought, and salinization of soils, there is a need to investigate AsA effects on tomato plants under salinity stress. In this context, the effects of applying ascorbic acid and salinity stress on some physiological parameters, key enzymes, namely superoxide dismutase (SOD) and ascorbate peroxidase (APX), and expression of LeNHX1 and SIERF16 genes involved in antioxidant system were studied in Lycopersicon esculentum Mill. plants in hydroponic conditions. Results showed that ascorbic acid treatments increased activity of SOD and APX and improved physiological parameters such as lipid peroxidation and Na+/K+ contents of tomato under salt stress via increases in LeNHX1 and SIERF16 genes expression.