THE EFFECT OF CHITOSAN ON GENE EXPRESSION, SOME MORPHOLOGICAL AND PHYSIOLOGICAL TRAITS OF SWEET BASIL (Ocimum basilicum L.) UNDER SALINITY STRESS

Sweet basil is an important medicinal plant belonging to Lamiaceae family. In this plant, Phenylpropanoid pathway possesses some enzymes involving in generating suitable essential oil constituents. The main purpose of conducting this study was to investigate the effects of chitosan on sweet basil's growth and physiological parameters as well as gene expression subjected to salinity stress. After employing a foliar-spray of chitosan at 0 (as control) and 0.2 gl(-1), the plants were subjected to salinity treatments at 0, 25, 50, 100, and 150 mM NaCl. The results of this research revealed that chitosan, compared to the controls, improved growth parameters under stressed or non-stressed conditions. In this regard, chitosan increased protein and chlorophyll contents as well as the expression of PAL and COVMT genes leading to an increase in phenolic compounds. To sum up, chitosan improved sweet basil tolerance to salinity through influencing the genes involved in the pathway of phenylpropanoid so as to produce secondary metabolites.