Effect of Salt Stress and PEG Iso-osmotic Stresses on Tomato Sugar Metabolism

Tomato(Lycopersicon esculentum Mill.) cultivar 'Liaoyuan Duoli' was used by the method of water culture.It was respectively treated with 50 mmo1.L-1 NaCl and PEG-6000 Iso-osmotic.The contents of soluble sugars and the related enzyme activities of sucrose metabolism were determined.The results showed that NaCl and PEG-6000 Iso-osmotic stresses enhanced the contents of fructose and glucose in tomato leaves,increased the activities of AI and NI,reduced the activities of SS and SPS.The effects of two stresses on sucrose contents were weak.The contents of fructose and glucose and invertase activities were higher under PEG stress than that under NaCl stress.These results suggested that NaCl and PEG stresses enhanced the contents of fructose and glucose in tomato leaves,which is due to changing that the activity of invertase activity affecting sugar accumulation.The contents of soluble sugars were higher under PEG stress than that under NaCl stress.