外源H2O2处理对唐古特白刺愈伤组织脯氨酸代谢的影响

以唐古特白刺（Nitraria tangutorum Bobr.）愈伤组织为材料，研究外源H₂O₂（2和10 μmol·L^-1）处理下其脯氨酸含量及相关代谢酶活性的变化，试图从细胞水平揭示H₂O₂影响脯氨酸代谢的生理机制。结果显示，2和10 μmol·L^-1 H₂O₂处理24 h使唐古特白刺愈伤组织脯氨酸含量分别变为对照的112%和92%，而处理72 h后，脯氨酸含量增加为对照的141%和119%；与对照相比，外源H₂O₂处理诱导愈伤组织脯氨酸脱氢酶活性降低，而谷氨酸激酶活性升高，但鸟氨酸转氨酶活性无显著变化；此外，H₂O₂处理使唐古特白刺愈伤组织内源性H₂O₂含量升高。结果表明，外源H₂O₂诱导了唐古特白刺愈伤组织H₂O₂含量的增高和脯氨酸的积累，且H₂O₂处理下脯氨酸脱氢酶活性的降低及谷氨酸激酶的升高与愈伤组织脯氨酸的积累有关。

Effect of Exogenous Hydrogen Peroxide on the Proline Metabolism in Nitraria tangutorum Bobr.Callus

In order to understand the regulatory mechanism of proline metabolism at the cellular level, Nitraria tangutorum Bobr. callus was used to investigate the effects of exogenous hydrogen peroxide (H₂O₂) treatment on the proline content and the activities of proline-related metabolism enzymes. After treatment with 2 and 10 μmol·L^-1 H₂O₂ for 24 h, proline content was about 112% and 92% of the control value in N.tangutorum Bobr. callus, respectively; at 72 h treatment, the amount of proline increased about 41% and 19% in comparison with the control. Analysis of enzyme activities showed that exogenous H₂O₂ induced remarkable decrease in proline dehydrogenase (ProDH) activity and significant increase in glutamyl kinase (GK) activity, but no significant changes in ornithine aminotransferase activity. In addition, the endogenous H₂O₂ level was increased in exogenous H₂O₂ treated callus. In conclusion, our results indicated that exogenous H₂O₂ treatment resulted in the significant increase of endogenous H₂O₂ content in N.tangutorum Bobr. callus. Here it was also indicated that H₂O₂ induced proline accumulation, which was associated with the reduction of ProDH activity and the elevation of GK activity in N.tangutorum Bobr. callus.