اثر پيش تيمار سديم نيتروپروسايد بر برخي عوامل بيوشيميايي گياهچه گوجه فرنگي Lycopersicun esculentumتحت تنش خشكي

The effect of sodium nitroprusside (SNP) pretreatment on some biochemical parameters in tomato seedlings (Lycopersicun esculentum) under drought stress

Drought stress is a major environmental constraint which inhibits the growth of plants and limits crop production. Nitric oxide (NO) is a relatively stable free radical gas which may act as a key signaling molecule in plants and mediates various physiological, pathophysiological and developmental processes and recently it has been suggested that it is involved in plant response to environmental stress. In this research sodium nitroprusside (SNP) was used as NO donor and 4,4,5,5-tetramethylimidazoline-l-oxy 1-3-oxide (PTIO) was used as a NO scavenger for 2 days in control and drought stressed plants, and the role of NO on some biochemical responses of Lycopersicun seedlings to drought stress was investigated. Data in this study showed that, SNP pretreatment decreased lipid peroxidation and hydrogen peroxide content in drought stressed plants. Drought stress and SNP pretreatment had no effects on photosynthetic pigments. Drought caused increase in carbonyl groups content and decrease in protein and non-protein thiol groups, an indicator of protein oxidation. However, SNP pretreatment reduced carbonyl content and increased thiol groups and alleviated the protein oxidation under drought stress. The amounts of proline, total free amino acids and soluble sugars increased significantly under drought stress. Treatment of plants with SNP only increased the proline content and had no effects on other osmolytes. Soluble phenols content as non-enzymatic antioxidant, increased under drought stress and SNP treatment increased the amount of these compounds. Pretreatment of plants with SNP and phenyl 4,4,5,5-tetramethylimidazoline-l-oxy 1-3-oxide (PTIO) (a NO scavenger) reduced the protective effects of SNP in our research, which suggests that the protective effect of SNP is exerted through NO release. The protective effects of NO in drought stress may be due to its ability to counteract reactive oxygen species (ROS) and reduce the oxidative damages.