The effect of salt stress and interaction with 5-aminolevulinic acid (ALA) on the activity of enzymatic antioxidants in (Lycopersicun esculentum Mill.) tomato plants

5-aminolevulinic acid is the key precursor of all tetrapyrrole compounds such as heme, chlorophylls, bacteriochlorophyll, phytochrome and vitamin B12. In this study, the effect of 5-aminolevulinic acid, in reduction of salt stress in Lycopersicun esculentum Mill. var. Falcato were studied. Salinity at three levels (0, 50 and 75 mM NaCl) and ALA treatment at three levels (0, 1 and 2 mM) were investigated in this study. Salinity reduced growth parameters, phenolics content and phenylalanine ammonialyase activity, and increased lipid peroxidation, ion leakage and the activity of superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase and guaiacol peroxidase. 5-aminolevulinic acid application in two levels increased the growth parameters, phenolics content, and the activity of phenylalanine ammonialyase, superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase and guaiacol peroxidase, and decreased lipid peroxidation and ion leakage. These results show that the application of 5-aminolevulinic acid, via enhancing the activity of enzymatic antioxidant system, is effective in salt tolerance of tomato plants.