RESEARCH PAPER Ameliorative Effects of Nitric Oxide on Oilseed Rape (Brassica napus L.) Under Water Stress M. Nikravesh 1 • B. Kholdebarin 2 • T. Nejad Sattari 1 • F. Najafi 3 Received: 3 January 2016 / Accepted: 1 March 2016 Ó Shiraz University 2018 Abstract The ameliorative effects of nitric oxide on oilseed rape seedlings, Okapy cultivar, under drought condition were inves- tigated. Water stress at 60 and 30% field capacity, increased lipid peroxidation and H 2 O 2 content in oilseed rape leaves. Among the different concentrations (25, 50, 75 and 100 lM) of sodium nitroprusside used, spraying plants leaves with 25 lM sodium nitroprusside a NO donor, reduced the damaging effects of water stress which was reflected by a decrease in malondialdehyde and hydrogen peroxide content in leaves. Drought stress enhanced leaves superoxide dismutase, per- oxidase and ascorbate peroxidase activities but decreased catalase activity. Sodium nitroprusside treatment (25 lM) had a positive effect on antioxidant enzymes under water stress. At higher sodium nitroprusside concentrations, its ameliorative effects on water stress were decreased and the oxidative damages to the leaves were sustained. The reduction in drought induced oxidative damages by NO in oilseed rape is most likely mediated by the NO ability to induce and increase the activity of reactive oxygen species scavenging enzymes. Keywords Antioxidant enzymes Á Water stress Á Nitric oxide Á Oilseed rape 1 Introduction The most important factors limiting crop productivity are environmental stresses (Mccue and Hanson 1990). In agriculture and horticulture, water stress is regarded as one of the main problem, leading to crop losses each year (Farooq et al. 2009). Because of the shortage in the world’s agricultural water supply, the demand for future food as a result of increasing population pressures is likely to further intensify the impacts of drought on crop production (Somerville and Briscoe 2001). Plants respond to water stress by different mechanisms that enhance their desic- cation tolerance and water retention. To deal with pro- longed drought stress, plants will respond with energy demanding procedures that modify their development pat- tern, chemical content and the up or down regulation of their genes (Shanker and Venkateswarlu 2011). The pro- duction of reactive oxygen species (ROS) so-called oxi- dants including superoxide (O 2 - ), hydrogen peroxide (H 2 O 2 ) and hydroxyl (OH Á ) free radicals under abiotic stresses such drought are the main factors damaging nor- mal plants growth and development (Halliwell 2006). ROS is believed to operate as second messengers engaging in the stress signal transduction pathway (Chamnongpol et al. 1998). High ROS production can result in oxidative stress, which damages the plants (Yordanov et al. 2000). Abscisic acid (ABA) is essential in plants response to water stress. It is due to the fact that it induces stomatal closure, which decreases water loss, which at the same time reduces CO 2 diffusion to photosynthetic fixation site and decreases NADP ? regeneration in Calvin cycle. These & B. Kholdebarin bkholdeb@susc.ac.ir; bkoldeb@biology.susc.ac.ir M. Nikravesh masoumeh_nikravesh@yahoo.com T. Nejad Sattari negadsattari_t@yahoo.com F. Najafi f_najafi@yahoo.com 1 Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran 2 Department of Biology, College of Sciences, Shiraz University, Shiraz, Iran 3 Department of Plant Sciences, Faculty of Biological Sciences, Kharazmi University, Tehran, Iran 123 Iran J Sci Technol Trans Sci https://doi.org/10.1007/s40995-018-0507-y