| Abstract: | Compounds which are able to reduce the damaging effects of various stresses such as drought should be of great importance. In this research we have used arginine pretreatment and the effect of this compound on alleviation of oxidative damages under drought stress has been investigated. Our findings showed that arginine pretreatment reduced the lipid peroxidation when water stress was imposed. In drought stressed plants, H2O2 increased and the activity of antioxidative enzymes were elevated over the controls, while glutathione reductase (GR) activity decreased. When plants pretreated with arginine, activity of catalase and guaiacol peroxidase decreased while the activity of superoxide dismutase (SOD), ascorbate peroxidase, and GR increased. Drought stress decreased ascorbate and reduced glutathione and increased dehydroascorbate. Opposite results were obtained after arginine pretreatment. When arginine was used as a precursor of nitric oxide (NO), the amelioration of the drought effects which was observed could well be the indication that these effects may be related to NO production. To prove that, we applied arginine + Nw-nitro-l-arginine methyl ester (LNAM) and on many parameters, arginine and arginine + LNAM pretreatment had the same effects and it seems that in these situations other pathways of arginine metabolism rather than nitric oxide synthase may be activated |
