Exogenous nitric oxide improves seed germination in wheat against mitochondrial oxidative damage induced by high salinity

Effects of exogenous nitric oxide (NO) on starch degradation, oxidation in mitochondria and K+/Na+ accumulation during seed germination of wheat were investigated under a high salinity level. Seeds of winter wheat (Triticum aestivum L, cv. Huaimai 17) were pre-soaked with 0 mM or 0.1 mM of sodium nitroprusside (SNP, as nitric oxide donor) for 20 h just before germination under 300 mM NaCl. At 300 mM NaCl, exogenous NO increased germination rate and weights of coleoptile and radicle, but decreased seed weight. Exogenous NO also enhanced seed respiration rate and ATP synthesis. In addition, seed starch content decreased while soluble sugar content increased by exogenous NO pre-treatment, which was in accordance with the improved amylase activities in the germinating seeds. Exogenous NO increased the activities of superoxide dismutase (SOD, EC 1.15.1.1) and catalase (CAT, EC 1.11.1.6); whereas decreased the contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2), and superoxide anions (O-2(center dot-)) release rate in the mitochondria. Exogenous NO also decreased Na+ concentration while increased K+ concentration in the seeds thereby maintained a balance between K+ and Na+ during germination under salt stress. It is concluded that exogenous NO treatment on wheat seeds may be a good option to improve seed germination and crop establishment under saline conditions. (C) 2009 Elsevier B.V. All rights reserved.