Isolation,Screening And Application Potenial Of Endophytes From Dendrobium Officinale

Dendrobium officinale Kimura et Migo,one of the most valuable and rarest traditional Chinese medicine,is honored as the first place of ‘ the nine Chinese herbs’.The main function of D.officinale is nourishing yin and clearing away heat-evil,tonifying the stomach and promoting fluid,moistening lung and lighting eyes,anti-tumor and anti-aging as well.As the increasing demands for D.officinale,the planting area is increasing continuously and the demand for seedlings is large.The universal application of facility cultivation and the increase of cultivation years make the disease of D.officinale become more and more serious which hinder the development of D.officinale industry.Abundant endophytes of D.officinale have been reported in many studies.Some of them have biocontrol activity and can promote growth of plants.In this study,an antagonistic microbe was isolated and screened from D.officinale and the role in biological control and plant growth have analysed.The aim is to provide physial resources for biological control and promotion of growth.The main results are as follow.1 、 24 strains of bacteria and 8 strains of fungi were isolated from wild D.officinale in Longquan.A strain with good antagonism was screened against Colledtrichum gloeosporides and Fusarium oxysporum and named DT-1.The antagonistic strain was identified as Talaromyces by orphological identification and molecular biology identification;2、The antimicrobial spectrum of strain DT-1 showed that strain DT-1 had good antagonism to 7 common pathogens.The fermentation broth of strain DT-1 could effectively inhibit the growth of C.gloeosporides.The growth rate of C.gloeosporides in mixed medium was lower obviously than in ordinary culture medium.Secondary metabolites of strain DT-1 were extracted from the fermentation broth.The production could efficiently inhibit the growth of mycelium and the newborn mycelium was thin and split,disorder and sparse.3、Strain DT-1 fermentation broth could promote the growth of tissue culture seedling of D.officinale.The average number of germination and rooting were up to7.67 and 8.54 respectively which were more than two times as much as the control.HPLC analysis showed that the concentration of auxin in the secondary metabolites of strain DT-1 was 3.23 ng/m L and the zeatin’s was 67.5 μg/m L,the gibberellin’s was 3.42μg/m L.4 、 Antagonistic fungus DT-1 could promote the natural germination of D.officinale seeds.20 mg/m L pectinase and 50 mg/m L snail enzyme were the best methods of enzymatic hydrolysis seed coat.10% DT-1 fermentation broth and 10%MS solution had a good germination effect on the seeds after treating with different incubating liquid.