the role of over expression of p5cs gene on proline, catalase, ascorbate peroxidase activity and lipid peroxidation of transgenic tobacco (nicotiana tabacum l.) plant under in vitro drought stress

in this study proline content and activity of catalase (cat), and ascorbate peroxidase (apx) and level of lipid peroxidation in terms of malondialdehyde (mda) content were measured in transgenic tobacco (nicotiana tabacum cv. wisconsin), over expressing a δ-1-pyrroline-5-carboxylate synthase (p5cs) gene, and non transgenic plants as control. drought stress was applied using polyethylene glycol (peg) 6000 at concentrations of 217, 264, 320, 637, 1292 mmol/kg equal to (0, 5, 10, 20, 30% respectively). proline content, especially in transgenic plants, was increased in leaves and roots significantly. cat and apx activities increased under drought stress and the highest activity was observed in 10 and 20% of the peg treatment. mda content was increased by increasing of peg and the highest mda content was revealed in transgenic and non transgenic plants at 20% and 30%, respectively. our results suggest that p5cs is an inducible gene and over production of proline and induction of cat and apx activities are involved in drought tolerance mechanism.