Leaf endophytic fungi of Cymbidium aloifolium L. produces antimicrobials and indole-3-acetic acid

Abstract

Endophytic fungi associated with healthy leaf tissues of Cymbidium aloifolium was investigated for their antimicrobial and indole acetic acid (IAA) production potential. Altogether, 39 endophytic fungal isolates were obtained from the 150 surfaced sterilized inoculated leaf fragments. The dominant endophytic fungal genera were Colletotrichum, Rhizoctonia and Fusarium. Non-sporulating endophytic fungi were also isolated and categorized as morphotype. Among the fungi, the colonization frequency (CF%) of the genus Colletotrichum was found to be the highest. All the isolates were determined for antimicrobial and IAA activity. Amongst the isolates, an endophytic fungus, identified as Colletotrichum gleosporioides showed promising antimicrobial and IAA producing activity. The crude metabolite obtained from the fungus was characterized by GCMS and HPLC analyzes. GCMS chromatogram revealed presence of squalene, farnesol, indole-acetic acid, tryptophan and benzene-ethanol-4-hydroxy as major components. These compounds were reported to have significant bioactive properties. HPLC study revealed presence of IAA in the crude fungal extract. Our findings indicated that orchid endophytic fungi are capable of producing bioactive secondary metabolites with antimicrobial and plant growth promoting potential which can be explored for application in medicine and agriculture.