低温胁迫对番茄幼苗叶片中脯氨酸降解酶的活性及其基因表达量的影响

Effect of Low Temperature Stress on the Expression of ProDH Gene and the Activities of the Proline Dehydrogenase in Leaves of Tomato Seedling

为了探讨脯氨酸代谢与番茄抗寒性之间的关系,采用常规方法测定了低温胁迫不同时间下番茄幼苗叶片中游离脯氨酸含量和脯氨酸脱氢酶活性,采用实时荧光定量PCR法检测了不同处理时间下脯氨酸脱氢酶基因的表达量,并分析了各项指标的动态变化。结果表明,在低温逆境下,耐寒性品种O-33-1中脯氨酸积累量总体呈增加的趋势,而冷敏感品种‘耐运2000’游离脯氨酸积累量下降,说明脯氨酸积累量的变化在一定程度上可以体现番茄抗寒性的强弱;ProDH活性在O-33-1中呈上升趋势,在‘耐运2000’中呈下降趋势,说明脯氨酸的积累受P5CS与ProDH相反方向的共同调节,使植物体内脯氨酸含量保持在适当的水平;2个品种在低温胁迫下ProDH基因表达量都显著降低,说明低温逆境抑制了该基因的表达,使脯氨酸的降解在转录水平上受到调节。

In order to explore the relationship between proline metabolism and cold resistance,the study focused on determination of proline content,proline dehydrogenase activity,the expression of ProDH,and analysis of dynamic changes of these indexes.The results indicated that change of proline accumulation,to a certain extent,reflect the strength of cold resistance of tomato,for that free proline accumulation showed overall an increasing trend in chill-endurance ＇O-33-1 ＇ ,and which was declined in cold-sensitive＇ Naiyun 2000 ＇ under low temperature stress.It explained the accumulation of proline depends on a common regulation of P5CS and ProDH to maintain the proline content in plants at an appropriate level,that ProDH activity increased in the ＇O-33-1＇ ,and discreased in ＇Naiyun 2000＇ .The relative expression of ProDH gene of two varieties was significantly decreased under low temperature stress.Therefore,the expression of the gene was inhibited under low temperature stress,so that the degradation of proline was regulated at the transcriptional level.