杜鹃兰种子萌发的限制因子及其作用机理研究

Cremastra appendiculata (D. Don.) Makino (Orchidaceae), a perennial, important and rare medicinal orchid. Its pseudobulbs are used as medicinal materials, an important and shortage medicinal materials for export. The wild resources of C. appendiculata are scarce, and there is an obvious contradiction between the market supply and demand. So, the artificial planting of C. appendiculata is pressing..We found the following issues when last National Natural Science Foundation on the physio-ecological adaptability C. appendiculata and the suitable conditions for artificial cultivation was implemented, namely, C. appendiculata could flowering normally, but its flowers can hardly pollination and fructification in natural condition. Higher seed setting rate could be gained by artificial pollination, but its seeds can hardly germinate naturally, and the seeds germination rate were also low extremely even under the condition of artificial control. So, the pseudobulbs are the only reproductive organs of C. appendiculata plants, and each pseudobulb can only produce a new pseudobulb in annual long-term, result in C. appendiculata can be not implemented large-scale artificial cultivation. Therefore, this study intends to adopt the methods combining the structure development observation of seed, substance metabolism testing in seed development, gene expression analysis of seed symbiotic germination, and ecological factors regulation in seed germination, to research the limiting factors in seed germination of C. appendiculata and expound their mechanism. This study was designed to provide the scientific basis solving finally the problem of the seed breeding technology, and building the technological system of seedlings scale breeding in artificial cultivation of C. appendiculata. It has great significance in theory, resources protection and industrial applications.

杜鹃兰是兰科重要珍稀药用植物，以假鳞茎（毛慈菇）入药，为重要紧缺中药材（重要出口药材）。该物种野生资源匮乏，市场供需矛盾突出，急需进行人工种植。在执行上一个国家自然科学基金项目“杜鹃兰的生理生态适应性与人工种植适宜条件研究”过程中，我们发现杜鹃兰植株能正常开花，但自然条件下几乎不能授粉结实；经人工授粉虽能获得较高结实率，但其种子几乎不能自然萌发，即使在人工控制条件下其萌发率也极低。故假鳞茎是其唯一的繁殖器官，而每个假鳞茎在一年生长期中只能产生1个新的假鳞茎，致使其人工种植不能规模化进行。为此，本项目拟从种子结构发育观测、种子发育物质代谢考查、种子共生萌发基因表达分析及种子萌发生态因子调控等方面，探索杜鹃兰种子萌发的限制因子并阐明其作用机理。本研究旨在为最终解决杜鹃兰种子繁殖技术问题、构建杜鹃兰人工种植中种苗规模化繁育技术体系提供科学依据，在理论、资源保护与产业化应用等方面均具有重要意义。

杜鹃兰为兰科重要珍稀药用植物，其假鳞茎是名贵中药材。杜鹃兰植株能正常开花，但自然条件下几乎不能授粉结实，无性繁殖（假鳞茎繁殖）也极其缓慢，致使其野生资源濒临枯竭。经人工授粉虽能获得较高结实率，但其种子几乎不能自然萌发。为此，课题组从种子结构发育观测、种子发育物质代谢考查、种子萌发生态因子调控、种子共生萌发基因表达分析等方面，系统研究了杜鹃兰种子萌发的限制因子及其作用机理。结果表明，种皮限制、种子无胚乳、种胚发育不良是构成杜鹃兰种子萌发障碍的主要因子；杜鹃兰果实成熟时其种胚处于原胚阶段，种子必须在适宜条件下完成胚后发育才能萌发；促萌发真菌与种子共生互作可有效促进杜鹃兰种胚发育和种子萌发。本研究在理论探索、资源保护与产业化应用等方面均具有重要意义。