Diversity, Phylogeny, anticancer and antimicrobial potential of fungal endophytes associated with Monarda citriodora L

Abstract

Background: Present study focuses on diversity and distribution analysis of endophytic fungi associated with different tissues of the Monarda citriodora Cerv. ex Lag. (Lamiaceae/Labiatae). Anticancer and antimicrobial potential of isolated endophytes have also been investigated.

Results: A total of twenty eight fungal endophytes belonging to 11 different genera were isolated from this plant. All the endophytic fungi belonged to the Ascomycota phylum. The leaves were immensely rich in fungal species, while roots showed the highest tissue specific fungal dominance. Out of 28 fungal species, 72% endophytic extracts were found cytotoxic against one or more human cancer cell lines. The most prominent anticancer activity (IC₅₀ value <10 μg/mL) was shown by MC-14 L (Fusarium oxysporum), MC-14 F (F. oxysporum), MC-18 L (Aspergillus fumigatus), MC-24 L (Cladosporium tenuissimum), MC-25 L (Fusarium sp.), MC-26 F (F. oxysporum) extracts. 75% of the extracts showed antimicrobial activities in agar disc-diffusion assay and 27% in the tube dilution method (MIC <100 μg/mL) respectively against the tested pathogens. Extracts of MC-14 L (F. oxysporum) and MC-18 L (A. fumigatus) displayed broad spectrum antimicrobial activity.

Conclusions: These results indicated that M. citriodora harbors a rich fungal endophytic community with anticancer and antimicrobial activities. The isolated endophyte MC-24 L (C. tenuissimum) has the potential to be a source of novel cytotoxic/antimicrobial compounds. This is the first report of diversity of fungal endophytes isolated from M. citriodora.

Keywords: Antimicrobial activity; Cytotoxicity; Endophytic fungi; MTT assay; Monarda citriodora; Tube dilution method.

Fig. 1

Phylogenetic position of the endophytic fungal isolates obtained from different tissues of the M. citriodora. The evolutionary history was inferred using neighbor-joining method [30]. The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (1000 replicates) is shown next to branches [32]. The evolutionary distances were computed using the maximum composite likelihood method [31]. Phylogenetic analyses were conducted in MEGA4 [28]