喜树幼苗中喜树碱及其代谢相关酶类的分布

Distribution of camptothecin and its metabolism-related enzymes in Camptotheca acuminata seedlings

目的分析当年生喜树Camptotheca acuminata幼苗各部位中喜树碱的量及其生物合成途径中色氨酸合酶(TSB)和色氨酸脱羧酶(TDC)的活性。方法用HPLC检测温室内不同氮素形态下砂培喜树幼苗各部位中喜树碱的量及TSB和TDC活性。结果不同氮素形态下喜树幼苗幼叶中喜树碱量明显高于其他器官(P<0.01),其次为茎皮和成叶,根中的最低。TSB活性在不同氮素形态下以幼叶最高,茎皮、成叶和根依次减弱,与喜树碱量呈现良好的器官对应性。不同氮素形态下TDC活性的最高部位为茎皮,其次为幼叶,成叶和根很低,与喜树碱的量缺乏器官对应性。结论当年生喜树幼苗喜树碱量以及TSB和TDC活性存在明显的组织器官特异性,喜树碱的量和TSB活性最高部位为幼叶,茎皮中TDC活性最大。

Objective To investigate the distribution of camptothecin （CPT）, tryptophan synthase （TSB）, and tryptophan decarboxylase （TDC） in Carnptotheca acurninata seedlings. Methods The CPT content, TSB and TDC activities in different organs of C. acurninata seedlings subjected to different nitrogen forms treatments by sand culture in greenhouse were determined by HPLC. Results The CPT content in the young leaves of C. acurninata seedlings with different N-forms was significantly higher than that in other organs （P〈0. 01）, then in the stem barks and the mature leaves, and the lowest in the roots. Under different N-forms, TSB activity was the highest in the young leaves, and decreased sequentially in the stem barks, the mature leaves, and the roots, which paralleled to CPT content. TDC activity was the highest in the stem barks of the seedlings with different N-forms, then in the young leaves, and the lowest in the mature leaves and the roots, which didn＇t parallel to CPT content. Conclusion CPT Content, TSB and TDC activities present differently in various organs of C. acurninata seedlings. CPT Content and TSB activity are the highest in the young leaves, TDC activity is the highest in the stem barks among the organs.