Acta Scientiarum Naturalium Universitatis Pekinensis

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Determination of Nitrogenase Activity of Induced Cucumber Nodules by 15N Trace Method

LI Xinghong1, TIAN Dexiang1, YU Zhongju1, WANG Yongmin1, CHEN Deyuan2   

  1. 1Department of Technical physics, Peking University, Beijing, 100871; 2College of Life Science, Peking University, Beijing, 100871
  • Received:1997-03-07 Online:1997-07-20 Published:1997-07-20


李星洪1, 田德祥1, 禹仲举1, 王永民1, 陈德元2   

  1. 1北京大学技术物理学系,北京,100871; 2北京大学生命科学学院,北京,100871

Abstract: Reports the determination results of nitrogenase activity of induced cucumber root nudules by 15N trace method. The root systems bearing induced nodules of cucumber were exposed to a gas mixture containing 15N2 for 48h and partial root systems soaked in free-nitrgen culture solution simultaneusly. After exposure the 15N content in the modulated root systems of cucumber is 0.431 Atom % 15N by mass spectrometric analysis, whereas in the contrast samples without exposure to 15N is 0.369 Atom % 15N. The statiatical t test for the results of 15N trace experiments is: t=3.15 > t0.01=2.819, It has been demonstrated that the nitrogenase activity in cucumber nudules is at a remarkable level of 99.9%. The nitrogenase activity in detached nodules of cucumber was also determined by conventional acetylene reduction method. In both methods clear evidences of nitrogenase activity were obtained for the induced nodules of cucumber.

Key words: 15N, nitrogenase activity, cucumber, acetylene-reduction method, trace method

摘要: 报道了用15N示踪标记法对人工诱发黄瓜根瘤固氮酶活性的测定结果。将长有人工诱发根瘤的黄瓜根系暴露在15N2的气体中,部分根系浸在无氮培养液内,标记48h后,质谱分析测定结瘤黄瓜根系中15N的丰度为0.431原子%15N,对照样品为0.369原子%15N,对15N示踪标记结果进行了统计学t检验,t=3.15>t0.01=2.819,表明黄瓜根系通过根瘤内细菌固氮作用所提供的氮与对照相比达99.9%极显著性水平,同时用乙炔还原法测定黄瓜离体根瘤的乙炔还原率每克鲜重为(0.299±0.076)μmol/h C2H4。两种方法测定结果表明人工诱发的黄瓜根瘤有显著的固氮活性。

关键词: 15N, 示踪标记, 黄瓜, 固氮活性, 乙炔还原法

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