【作者】 唐中华；

【导师】 祖元刚；

【作者基本信息】 东北林业大学 ， 植物学， 2002， 硕士

【摘要】 应用高效液相色谱技术对我国特有树种——喜树(Camptotheca acuminata)在种子形成、成熟、萌发、幼苗生长及高温胁迫过程中喜树碱和10-羟基喜树碱的代谢动态进行了详尽的研究。结果发现，喜树碱和10-羟基喜树碱像大多数其它生物碱一样，特异性地受到组织发育程度和环境因子的调控，特别是10-羟基喜树碱趋向于在成熟过程中的种子中、吸胀第12～13天的种芽中、新出现的子叶中、幼嫩叶片中和高温胁迫后的幼嫩组织中大量积累，这些幼嫩的和受到生理胁迫的组织也是植物必须特别保护的部位，这也从另一个侧面说明10-羟基喜树碱肯定直接参与了喜树化学防御的过程，而喜树碱主要充当贮藏库和提供代谢源的任务，是一个常规的防御措施，所以它受发育和环境因子调控的程度也就比10-羟基喜树碱低：在高温胁迫条件下，喜树碱和10-羟基喜树碱分别在38℃和40℃度达到各自的峰值，比以丙二醛和叶绿素为指标的致死温度低了2～4℃，说明喜树碱和10-羟基喜树碱作为喜树的化学防御手段在喜树受到生理胁迫的最前期就已被启动，对于缓解喜树的生理胁迫起到了积极的作用，其作用机制可能是10-羟基喜树碱通过中和由胁迫诱导的酸性物质，从而稳定细胞质中的在生理活性范围内而缓解植物生理胁迫；关于喜树碱和10-羟基喜树碱之间的关系，我们认为喜树碱羟基化形成10-羟基喜树碱的反应可能不是单向的，而是可逆的，后者去羟基化后可以转化为喜树碱，这是处于生长和防御两难境地的植物充分利用有限量的氮资源必然的要求。更多还原

【Abstract】 Camptotheca acuminata is a tree unique to China, producing terpenoid indole alkaloid (TIA) 10-Hydroxycamptothecin (HCPT) and camptothecin (CPT), which possess strong anti-cancer bioactivity. The dynamics of HCPT and CPT during seed maturation, seed germination, post-germinative development and daily growth were measured by HPLC (High Performance Liquid Chromatography). This paper provides some evidence for presenting the theory that each characteristic of HCPT and CPT accumulation is under developmental regulation and then attempt to elucidate the metabolic relationships between them. The results revealed that HCPT accumulates particularly in young tissues and organs and is relatively unstable, while the distribution of CPT is more ubiquitous and stable. Their different distribution properties suggest that HCPT and CPT were differentially regulated during development and HCPT is the special defensive strategy for Camptotheca. CPT, however, is a universal tactic.Plants interact with their environment by producing a diverse array of secondary metabolites, one of which is alkaloid. In this paper, alkaloid, including Camptothecin (CPT) and 10-hydroxycamptothecin (HCPT), malondialdehyde (MDA) and chlorophyll contents were measured during heat shock in Camptotheca acuminate seedlings. Responses of different tissues, including young leaves, old leaves, shoots and barks, to heat shock were examined in alkaloid changes. CPT and HCPT concentrations reached to their peak values separately at 38癈 and 40癈 , which were before the lethal heat-shock temperature indicated by MDA and chlorophyll, and their great changes took place in young leaves. These results indicated that CPT and HCPT are involved in the C. acuminata resistance against heat shock from its environment. Furthermore, plant rigidly observed the cost-benefit principle and mobilized and allocated limited alkaloid sources to young and reproductive tissues preferentially. In addition, HCPT displayed well-regulated changes during incubation at sublethal temperature and this indicated that HCPT may play a more positive defensive role in enhance of plant thermotolerance than CPT does.更多还原