Changes on proline, phenolic compounds and activity of antioxidant enzymes in Anethum graveolens L. under salt stress

Salt stress as a major adverse factor can lower leaf water potential, leading to reduced turgor and some other responses, and ultimately lower crop productivity in arid and semi arid zones. In In this study, Seedlings of Anethum graveolens were subjected to 0, 25, 50, 75 and 100 mM NaCl. Changes in morphological traits, proline content, total phenol and activity of antioxidant enzymes such as ascorbate peroxidase (APX) and polyphenol oxidase (PPO) in shoot and root were evaluated. As a result, APX and PPO activities in root and shoot significantly increased while root and shoot dry weight decreased progressively. The total amount of the phenolic and free proline also increased after the NaCl treatment. The increase was dose-dependent. The highest amount of free proline achived at 100mM NaCl which was about 9-fold and 3-fold higher than control in root and shoot, respectively. higher than control. Our results support the idea that the activities of APX and PPO and accumulation of total phenol and proline is associated with salt tolerance as oxidative responses.