摘要:
研究了Pb2+对桐花树幼苗氮代谢关键酶活性及膜脂过氧化的影响。结果表明:0.1～2.0mmol·L-1Pb2+胁迫使营养液中培养的桐花树幼苗根、茎、叶的NADH-GOGAT活性降低,丙二醛含量增加,使根和茎的GS活性降低,而叶的GS在0.1～1.0mmol·L-1Pb2+胁迫下活性增加高于对照,但受2.0mmol·L-1较高浓度Pb2+抑制。无论是否有Pb2+胁迫,叶的GS活性都高于茎和根,而根的NADH-GOGAT活性始终高于茎和叶。根的GS和NADH-GOGAT活性受Pb2+胁迫抑制的程度明显大于茎、叶,Pb2+对根的初级氮代谢影响最大。MDA含量与GS和NADH-GOGAT活性呈负相关关系。
Abstract:
The effect of Pb2+ stress on nitrogen metabolism and membrane lipid peroxidation in Aegiceras corniculatum seedlings was investigated.The activities of NADH-GOGAT and GS,soluble protein,and MDA content in the roots,the stems and the leaves of A.corniculatum seedlings,which were cultivated for 30 days in nutrient solution containing Pb2+,were analyzed.The results showed that the NADH-GOGAT activities in A.corniculatum seedling roots,stems,and leaves decreased under Pb2+ stress,while the contents of soluble proteins and MDA increased.The GS activities in the roots and stems decreased due to Pb2+ treatments with concentrations ranging from 0.1 to 2 mmol·L-1.GS activities in the leaves increased and was higher than that of the control.However,the activity was inhibited by Pb2+ at higher concentration of 2 mmol·L-1.Whether Pb2+ was added to the nutrient solution or not,the GS activity in the leaves was higher than those in the roots and stems.The GOGAT activity in the roots was higher than those in the leaves and stems.GS and NADH-GOGAT in roots were more sensitive to Pb2+ stress than those in stems and leaves.Thus,Pb2+ had the most effect on primary nitrogen metabolism in the root.It was also suggested that there was a negative correlation between the MDA content and the NADH-GOGAT or GS activity.
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