低温胁迫对番茄幼苗脯氨酸积累及其代谢关键酶活性的影响

以抗寒性不同的3个番茄品种‘耐运2000’、‘京乐502’和‘O-33-1’为试材，采用常规方法测定不同低温胁迫时间和不同低温胁迫温度下番茄幼苗叶片中脯氨酸含量、吡咯啉-5-羧酸合成酶(P5CS)活性、鸟氨酸转移酶(8-0AT)活性、脯氨酸脱氢酶(ProDH)活性的变化，以期探讨番茄的脯氨酸代谢对低温胁迫的响应机制及其与抗寒性的关系。结果表明：番茄幼苗叶片中的脯氨酸含量随低温胁迫时间的延长和温度的降低均呈先升高后降低的趋势，冷敏感品种‘耐运2000’的平均脯氨酸含量较低，抗寒性越强的品种的脯氨酸保护阈值越大；番茄幼苗叶片中P5CS和8-0AT活性随低温胁迫时间的变化均呈现先升后降的趋势，与脯氨酸积累正相关。在不同低温胁迫温度下，对低温越敏感的品种P5CS和8-0AT活性随温度的变化程度越大；当低温处理1天时，番茄叶片中脯氨酸含量下降，ProDH活性显著增加；随后ProDH活性呈现先降低后升高的趋势，这与脯氨酸的积累呈负相关。在不同低温胁迫下，番茄叶片中ProDH活性在一定低温范围内均出现降低以减少对脯氨酸的降解，增强植株的抗寒能力。

Effect of Low Temperature Stress on Proline Accumulation and the Activities of the Key Enzymes Involved in the Proline Metabolism in Leaves of Tomato Seedling

In order to study the effects of low temperature stress on proline accumulation and the activities of the key enzymes involved in the proline metabolism, explore the relationship between proline metabolism and cold resistance, the experiment focused on determination of free proline content, pyrroline-5-carboxylate synthetase (P5CS) activity, ornithine-oxo-acid transaminase (8-0AT) activity, proline dehydrogenase (ProDH) activity, and analysis of dynamic changes of these indexes. Three tomato varieties, ‘Naiyun 2000’, ‘Jingle 502’, ‘O-33-1’, were used as the experimental materials. The results showed that the free proline accumulation increased and then decreased under low temperature stress, and the average proline content were lower in cold-sensitive ‘Naiyun 2000’, which can reflected the strength of cold resistance of tomato. Along with the increasing time of stress, the changes of P5CS activity and 8-0AT activity showed just same as the tendency of free proline. The ProDH activity increased obviously after one day while the free proline content decreased, and then showed a trend of decreased at first and then decreased which was contrary to the accumulation of free proline.