Nitric oxide enhances the adaptive responses of lupine plants against heavy-metal stress
Australian Journal of Crop Science
The present work investigates the possible protective role of nitric oxide (NO) against heavy metals stress in Lupinus termis L. plants. A greenhouse experiment was conducted as a 2 x 2 factorial design with five replications. Lupine seedlings were treated with two concentrations (0.4 mM and 0.6 mM) of sodium nitroprusside (SNP as an NO donor) and subjected to high levels of nickel (Ni) sulfate (100 and 150 mM). The toxic effects of Ni on L. termis plants were evaluated by measuring the
... asuring the oxidative stress markers such as lipid peroxidation, hydrogen peroxide and electrolyte leakage. In addition, growth parameters, endogenous phytohormones, photosynthetic pigment, calcium, magnesium and Ni accumulation in lupin plants grown under Ni toxicity in the presence or absence of NO were also determined. Carbohydrate, organic acid and proline contents were also measured to determine the possible NO-mediated defense strategies in lupine plants to resist Ni stress. The obtained results proved that, Ni toxicity resulted in significantly elevated levels of oxidative stress markers, as well as abscisic acid, jasmonic acid and proline contents, which are associated with significant reduction in growth parameters, photosynthetic pigments, carbohydrate, indole acetic acid and gibberellic acid contents compared with control plants. SNP treatments significantly alleviated the toxic effect of Ni on Lupinus termis L. and increased the amounts of proline, soluble sugars and polysaccharides in shoots and roots, which could be an induced defensive mechanism against heavy-metal stress. Treatment with 0.4 mM SNP was more effective in increasing lupine plants tolerance to Ni toxicity than the 0.6 mM SNP.