Antifungal Activity of Endophytic Fungi Associated with Echinacea purpurea
Endophytic fungi are microorganisms that live in intercellular plant tissue without causing apparent negative effects for the host. These microorganisms are living in association with medicinal plants and have received increasing attention after the discovery that the endophytic fungus Taxomyces andreanae recovered from Taxus brevifolia, produce the anticancer paclitaxel (Taxol®). In addition, recent studies have demonstrated that the endophytic fungal communities living within medicinal plant tissues produce a wide range of metabolites with different biological activities that may be useful as scaffolds for the development of new drugs. E. purpurea is the best known of the species of the genus Echinacea, used mostly to stimulate the immune system. The aim of the present study was to determine whether any of the endophytic fungi associated with E. purpurea produced metabolites with antifungal activity. Fragments of healthy leaves and upright flower stalks of 42 plants of E. purpurea were subjected to surface sterilization and inoculated on potato dextrose agar. A total of 246 endophytic fungal isolates were recovered from 410 fragments of the plant tissues (131 from leaves and 115 from upright flower stalks). Susceptibility testing against phytopathogenic Colletotrichum species was performed using dichloromethane (DCM) crude extracts of each endophytic fungus with a final concentration of 160 µg/mL. The DCM extracts from 103 (41.9%) endophytic fungi isolates displayed moderate antifungal activity against the spore germination of at least one target fungus. While eight (3.2%) extracts displayed clear zones of fungal growth inhibition in all phytopathogenic fungi tested in the direct TLC bioautography system. Our research showed the presence of endophytic fungi associated with the medicinal plant E. purpurea and that are able to produce bioactive compounds that may be useful as sources of novel biopesticides.
Acknowledgements: Funding from Fapemig.