Physiological Effects Of GSNO On Tomato Salt Stress

Secondary salinization of protected soil has become one of the most important factors limiting the growth and yield of protected crops.Tomato is one of the main vegetable varieties cultivated in protected crops.The secondary salinization of soil in protected crops seriously affects the yield and quality of tomato.Therefore,it is very important to improve the salt adaptability of tomato.GSNO（S-nitrosoglutathione）is a kind of nitrosomercaptan compound,which is a natural donor of No.Previous studies have shown that endogenous GSNO plays an important role in signal transduction and plant defense response to abiotic stress.In this study,"Zhongshu 4"tomato seedlings were used as experimental materials.Nutrient solution cultivation method was used.The effects of GSNO(0,0.1,0.2,0.3,0.4,0.5,0.6 mmol·L^-1)foliar spray on the growth of Tomato Seedlings under NaCl(100 mmol·L^-1)stress were studied.1.2.Using chemical genetic method（pharmacological method）,GSNO(0.1 mmol·L^-1),pito(0.05 mmol·L^-1)and gsnp+pito were sprayed on the leaves under NaCl stress to construct different levels of endogenous NO,and to study the mechanism of GSNO regulating salt adaptability of tomato seedlings.The main results are as follows:1.Exogenous application of 0.1-0.3 mmol·L^-1 GSNO can effectively alleviate the inhibition of salt stress on Tomato Seedling Growth and improve salt adaptability by increasing chlorophyll content,root activity and proline content,reducing membrane lipid peroxidation and membrane integrity damage to varying degrees,especially 0.1 mmol·L-1 GSNO.However,the application of high concentration(0.5-0.6 mmol·L^-1)GSNO in this experiment has caused damage to Tomato Seedlings under salt stress,but it has not yet achieved the effect of inhibiting the growth of Tomato Seedlings under salt stress.2.Exogenous 0.1 mmol·L^-1 GSNO significantly increased the root activity and the content of osmotic regulation substances（pro and soluble sugar）of Tomato Seedlings under NaCl stress.Under salt stress,GSH in leaves of tomato seedlings was increased,SOD,pod,cat,GPX and As A-GSH cycle key enzyme activities were regulated,ROS clearance and antioxidant capacity were improved.The photosynthetic pigment content,Apparent Photosynthetic quantum efficiency,Rubisco maximum carboxylation efficiency and Ru BP maximum regeneration rate of Tomato Seedlings under NaCl stress were significantly increased,the dark respiration rate was reduced,the damage of photosynthetic mechanism under NaCl stress was reduced,and the net photosynthetic rate was increased.Under NaCl stress,the level of endogenous NO in tomato leaves and the activities of NR,NIR,GS,GOGAT and GDH,which are related to the pathway of nitrogen metabolism,were increased to promote the ability of nitrogen assimilation.Therefore,the inhibition of NaCl stress on the growth of tomato seedlings and the improvement of salt adaptability of tomato were alleviated,while exogenous application of 0.05 mmol·L-1 pito weakened the effects of GSNO on the osmotic regulation,ROS clearance,antioxidant capacity,photosynthetic energy and nitrogen metabolism of Tomato Seedlings under NaCl stress.These results showed that exogenous GSNO could effectively alleviate the inhibition of salt stress on the growth of tomato seedlings and improve the salt adaptability,which was related to the level of endogenous NO.