Molecular identification of three endophytic fungi from eucalyptus leaves and their pathogenicity

Abstract

Eucalyptus leaves have antibacterial, antiviral, and antifungal components and have been use to treat colds, influenza, rhinitis, sinusitis, and other respiratory infections. Endophytic fungi can produce secondary metabolites similar to their hosts. The research was performed to assess the pathogenicity of species-specific endophytic fungi isolated from Eucalyptus leaves on Eucalyptus citriodora plantlets through in vitro inoculation and molecular identification. This research was conducted at the Indonesian Spice and Medicinal Crop Research Institute, Plant Protection Laboratory, from July 2020 – May 2021. Isolation of endophytic fungi was done by direct planting method, whereas purification and characterization of fifty isolates were conducted on Potato Dextrose Agar (PDA) media for their activity as antimicrobial. Based on ITS sequence analysis, the DNA sequences of isolate A-TKR1 were identical to Aspergillus flavus, isolate E-TKR3 to Penicillium citrinum, and isolate ECT- TKR7 to Neofusicoccum parvum. The similarity of those isolates was 100%, 99.81%, 99.82%, respectively. The re-isolation analysis of infected tissues showed that A. flavus, P. citrinum, and N. parvum matched Koch’s postulates and confirmed endophytes’ presence within living tissues.