不同真菌对2种药用石斛种子共生萌发的效应

兰科石斛属植物兜唇石斛Dendrobium aphyllum和齿瓣石斛D.devonianum均为传统中药材,有着极高的药用价值。研究利用3种从不同兰科植物中分离得到的内生真菌在不同光照条件下与这2种石斛植物种子在树叶、松树皮和椰糠混合基质上进行共生萌发试验。研究结果表明,胶膜菌属Tulasnella FDaI7菌株及瘤菌根菌属Epulorhiza FDd1菌株分别能有效地促进兜唇石斛和齿瓣石斛种子的萌发及幼苗建成,石斛与真菌存在共生专一性。共生培养60 d,接菌FDaI7的兜唇石斛种子,原球茎或幼苗形成率分别为14.46%,12.07%;接菌FDd1的齿瓣石斛种子,二者形成率分别为44.36%,42.91%。在2种光照条件下,已形成的原球茎均能够进一步发育为幼苗,而持续黑暗条件会导致幼苗白化或畸形。研究结果为2种石斛的野外回归奠定了理论基础,也为这2种药用石斛人工仿生态栽培的种苗扩繁提供了新的方法。

Effects of different fungi on symbiotic seed germination of two Dendrobium species

The epiphytic orchid, Dendrobium aphyllum and D. devonianum are used as traditional Chinese medicine, and became locally endangered in recent years because of over-collection. We test the effect of inoculations of endophytic fungi FDaI7 (Tulasnella sp.), FDd1 (Epulorhiza sp.) and FCb4 (Epulorhiza sp.), which isolated from D. aphyllum, D. denonianum and Cymbidium mannii, respectively, on artificial substrate in these two Dendrobium species. In the symbiotic germination experiment, FDaI7 and FDd1 were effective for protocorm formation and seedling development of D. aphyllum and D. denonianum separately. After 60 days, 14.46% of the D. aphyllum seeds grown to protocorms and 12.07% developed to seedlings inoculated only with FDaI7, while contrasted with 0 when inoculated the other two isolates and non-inoculation treatment. However, in D. denonianum, seeds only grown to protocorms and developed to seedlings when inoculated with FDd1, the percentages were 44.36% and 42.91% distinguishingly. High specificity was shown in symbiotic germination on artificial substrate of Dendrobium. Protocorms could further develop to seedlings within or without light when inoculated the compatible fungi. However, light condition (12/12 h Light/Dark) produced the normal seedlings, while dark condition (0/24 h L/D) produced the abnormal seedlings. These may suggest that the development of young seedlings require light based on the effective symbiotic fungi. These findings will aid in seedling production of simulation-forestry ecology cultivation, conservation and reintroduction of Dendrobium.