Isolation And Antifungal Activities Of Endophytic Fungi From Ginkgo Biloba L

The plant endophytic fungi metabolize some interesting secondary metabolites with novel structures and distinctive activities, which are important sources of new biopesticide, and have extensive prospects in agricultural application. This research obtains endophytic fungi T-4and T-7from Ginkgo biloba L, which strikingly antagonized kinds of plant pathogens. In this present paper，biological characteristics and antimicrobial activities of the strains were studied. The main results are as follows:1. Twenty-six endophyte isolates were obtained from healthy roots, stems and leaves of Ginkgo biloba L. The results of the preliminary experiments exhibited that17endophyte isolates strong antagonized six plant pathogens, Phytophthora capsici(PC), Fusarium oxysporum(FO), Cytospora mandshurica(CM), Colletotrichum gloeosporioides(CG), Venturia pirina(VP) and Fusarium graminearum(FG). Especially, the endophyte T-4and T-7strain. The values of inhibitory rate of both strains against the six test pathogens were over50%. Especially, against CM were over90%, respectively. T-7strain against PC inhibitory rate was more than90%. T-4strain rate was85%against FO.2. The T-4and T-7strain were identified as Fusarium sp., T-7strain was identified as Fusarium solani based on ITS rDNA sequence analysis. Biological characteristics researched different conditions in temperature, light, pH value, carbon and nitrogen sources, cultural media. The results are as followed: The proper growth temperature of the two strains was28℃-32℃. Strain T-4grew well in the scope of pH7-9, while the value of pH was6-10in strain T-7. In addition, the optimal carbon source of T-4growth was maltose and glucose while the optimal nitrogen source was tryptone the great carbon source of T-7was lactose while the nitrogen source was NaNO3. Strain T-4grew well on PDA and PSA medium, and T-7in NA medium. Nevertheless, the growths of T-4and T-7were neither affected in light conditions.3. By flask fermentation, the mycelia and fermented broths were isolated and the assessments of antifungal activities of the26strains’ metabolites were carried out, respectively. The results showed that the ethyl acetate extracts had weak affections against the six test plant pathogenic fungi at the concentration of200mg/l. Furthermore, the fermented broths of strain T-4and T-7could strong inhibit the mycelial growths of CM, CG, VP, FG and FO. And the values of inhibitory rate against CM were more than90%and85%, respective. By potting experiment, the results showed that the therapeutic and protective effects of T-7fermented broth against PC were15.43%and23.17%, respectively. Unfortunately, the effects of T-4were not observed.