| Five Dendrobium species are recorded in the Pharmacopoeia of Peoples Republic of China as herba Dendrobii, D. candidum is one of the rarest and the most effective medicinal plants. Owing to the excessive usage and its unique physiological characteristics, the natural resource of D. candidum is on the brink of extinction. So, it is very urgent to meet the needs of D. candidum through culture it artificially in large scale in the room or in the field.The application methods were systematically studied for the interactions between D. candidum protocorms and fungal elicitor MF24 which was isolated from the roots of D. candidum. And the same time, the chemical compositions among D. candidum protocorms induced by the elicitor, the seedlings of D. candidum and D. nobile collected in natural condition were compared by HPLC-MS. The effects of elicitor on the content of compounds of D.candidum protocorms were also studied. The main results are summarized as follows.1. The effects of fungal elicitor in different conditions on the growth and secondary metabolites of D. candidum protocorms were studies such as the optimal treatment method of fungal elicitor, its amount, supplemented time, and its handling time. The results showed that the optimum culture technology is using the fermentation broth of MF24, adding 250mL · L-1 (elicitor · culture medium-1 ), supplementing it sixteen weeks while D. candidum inoculated, handling D. candidum six weeks after fungal elicitor added. In this way, dry weight per bottle of D. candidum protocorms could increase by 28% and the content of total alkaloid could increase by 12% compared with contrast.2. Total ion chromatograms (TIC) of D. candidum protocorms induced by fungal elicitor, contrast protocorms, seedlings of D. candidum and D. nobile wrer obtained by means of HPLC-MS. Extracted ion chromatograms (EIC) are as following.The relative area of alkaloids account for 6.04% and 43.15% in seedlings of D. candidum and D.
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