Endophytic fungi from the medicinal herb Euphorbia geniculata as a potential source for bioactive metabolites.

Abstract

Many researchers proved that plant endophytes manage successful issues to synthesize active chemicals within plant cells. These bioactive compounds might support a range of plant defense mechanism against many pathogenic microorganisms. In this study, a total of 22 isolates representing 21 fungal species belonging to 15 fungal genera in addition to one variety were isolated and identified for the first time from Euphorbia geniculate plants. The genus Aspergillus was the most common fungus isolated from the studied plant. The fungus Isaria feline was recorded in both leaves and stem, while Aspergillus flavus, A. ochraceus, A. terreus var. terreus, Emercilla nidulans var. acristata, Macrophomina phaseolina colonized both stem and root. The isolated fungi showed antagonistic activities against six strains of plant pathogenic fungi viz., Eupenicillium brefeldianum, Penicillium echinulatum, Alternaria phragmospora, Fusarium oxysporum, Fusarium verticilloid, and Alternaria alternata in dual culture assay. The highest antagonistic activity fungal species (Aspergillus flavus, A. fumigatus, and Fusarium lateritium) and the lowest (Cladosprium herbarum, F. culomrum, and Sporotrichum thermophile) showed twining in their secondary metabolites especially terpens and alkaloids with that of their host E. geniculata. Three concentrations of (0.5, 1.0, and 2.0mg/ml) of these secondary metabolites extracted by ethyl acetate and n-butanol from the above six endophytic fungal species were tested against three pathogenic fungi isolated from infected tomato plant (E. brefeldianum-EBT-1, P. echinulatum-PET-2, and A. phragmospora-APT-3), whereas these pathogens showed promising sensitivity to these fungal secondary metabolites. In conclusion, this is the first report on the isolation of endophytic fungi from E. geniculata and evaluation of their antifungal activity.