Exogenous application of nitric oxide and spermidine reduces the negative effects of salt stress on tomato

Due to increasing soil salinity, the world agricultural output is being threatened by the shrinking area of fertile land. In the present study, we explored the interactive roles of nitric oxide (NO; 100 mu M) and spermidine (SP; 200 mu M) in ameliorating the effects of salt stress (NaCl; 100 mM) in tomato (Solanum lycopersicum L. var. Five Star) seedlings. NaCl stress reduced shoot and root length, shoot and root fresh weight, shoot and root dry weight plant (-1) and leaf area leaf (-1). NaCl stress also suppressed the biosynthesis of photosynthetic pigments (Chlorophyll a and b) and increased proline (Pro) content, membrane damage and lipid peroxidation by inducing reactive oxygen species (H2O2 and O-2 (aEuro cent -) ) generation in roots and leaves, as well as electrolyte leakage (EL) and malondialdehyde (MDA) accumulation in leaves. However, applying NO and/or SP increased the activities of catalase, peroxidase, superoxide dismutase, glutathione reductase and ascorbate peroxidase and increased photosynthetic pigment (chlorophyll a and b) and Pro accumulation, as well as reducing H2O2 and O-2 (aEuro cent -) and MDA content and EL, under salt stress. When tomato plants were treated with NO and SP simultaneously, NO signaling was further enhanced, which was confirmed by the addition of cPTIO [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; NO scavenger].