Ornithine pathway in proline biosynthesis activated by salt stress in barley seedlings

C-14-glutamate and C-14-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.