Studies On Secondary Metabolic Regulation Of Endophytic Fungus From Ephedra Sinica Stapf And The Relation With Its Host Plants

There are a variety of endophytic fungi in medicinal plants, and they can not only produce bioactive metabolites with unique composition, but also synthetize secondary metabolites that with the same or similar physiological functions as their host plants. The research on secondary metabolites of endophytic fungus is still in infancy, and the regulaion of secondary metabolites has been rarely reported. The strain Mh5 is an ephedrine-producing endophytic fungus isolated from Ephedra Sinica and it was used to study the regulation of precursors, metal ions and phosphate on its secondary metabolites.In this research, phenylalanine, methionine and tyrosine were used to investigate the regulation of precursors on the yield of ephedrine. And the results showed that the yield of ephedrine would be effectively improved if the suitable concentration of precursors was added at the appropriate time. Phenylalanine and methionine should be added at the initial stage of the stationary phase, and tyrosine should be added at the end of the stationary phase. The appropriate concentrations of them were 7 mg/1,5 mg/1 and 7 mg/1, and the yield of ephedrine increased by 154.81%,183.70% and 84.71%, respectively. Subsequently, different concentrations of metal ions including Mg2+,Mn2+, Fe2+, Zn2+, Co2+, Ca2+ were used to investigate their effect on the yield of ephedrine, and the optimal concentration for the accumulation of ephedrine was selected. The results showed that the yield of ephedrine could be effectively improved by 20 mmol/l Mg2+,0.1 mmol/l Mn2+,0.1 mmol/l Fe2+,0.1 mmol/l Zn2+,0.01 mmol/l Co2+ and 0.5 mmol/l Ca2+, especially Mg2+,Mn2+,Fe2+ can increase it to 119.02%,102.84% and 103.33%, respectively. The yield of ephedrine of Mh5 was increased by 86% by adding phosphate at the concentration of 0.001 mmol/l.To investigate the relationship between endophytic fungus from E. sinica and its host plant, we studied the influence of strain Mh1, Mh2, Mh3, Mh4 and Mh5 for the ephedra seed germination and plant growth, as well as seed extracts for the yield of ephedrine of Mh5. From the results, we can conclude that the germination of ephedra seed could be promoted by the suspension of Mh5, the inactivated hypha of Mh4 and the fermented broth of Mh2, and the germination rate increased by 11.11%,7.78% and 3.34%, respectively. Furthermore, the fermented broth of the five endophytic fungus from E. sinica can facilitate the growth of ephedra plantlets at different extent, and the fermented broth of Mhl increased the fresh weight of ephedra by 51.35%, and that of Mh5 increased ephedra height and root length by 65.38% and 27.59%. Otherwise, the mycelial growth and the production of ephedrine were inhibited by the extract of ephedra seed.