Ornithine Pathway in Proline Biosynthesis Activated by Salt Stress in Barley Seedlings

C_glutamate and 14 C_arginine were spreaded on leaves of six_day old barley (Hordeum vulgare L.) seedlings that were treated with NaCl 200 mmol/L. The result showed that the pathway of arginine→ornithine→proline existed in the six_day old barley seedlings and was provoked remarkably by NaCl treatment. After seven days, proline accumulation contributed via the arginine→ornithine→proline pathway was 1.0- 1.5 folds of that via the glutamate→proline pathway. The activation of arginine→ornithine→proline pathway by salt stress in the salt_tolerant cultivar “Jian 4 was 1.7-2.0 folds of that in the salt_sensitive cultivar “KP 7, which suggested that the activation of arginine→ornithine→proline pathway in barley seedlings played an important role in improving salt tolerance of plants.