A Metabolomic Study of Epichloë Endophytes for Screening Antifungal Metabolites

Abstract

Epichloë endophytes, fungal endosymbionts of Pooidae grasses, are commonly utilized in forage and turf industries because they produce beneficial metabolites that enhance resistance against environmental stressors such as insect feeding and disease caused by phytopathogen infection. In pastoral agriculture, phytopathogenic diseases impact both pasture quality and animal production. Recently, bioactive endophyte strains have been reported to secrete compounds that significantly inhibit the growth of phytopathogenic fungi in vitro. A screen of previously described Epichloë-produced antifeedant and toxic alkaloids determined that the antifungal bioactivity observed is not due to the production of these known metabolites, and so there is a need for methods to identify new bioactive metabolites. The process described here is applicable more generally for the identification of antifungals in new endophytes. This study aims to characterize the fungicidal potential of novel, ‘animal friendly’ Epichloë endophyte strains NEA12 and NEA23 that exhibit strong antifungal activity using an in vitro assay. Bioassay-guided fractionation, followed by metabolite analysis, identified 61 metabolites that, either singly or in combination, are responsible for the observed bioactivity. Analysis of the perennial ryegrass-endophyte symbiota confirmed that NEA12 and NEA23 produce the prospective antifungal metabolites in symbiotic association and thus are candidates for compounds that promote disease resistance in planta. The “known unknown” suite of antifungal metabolites identified in this study are potential biomarkers for the selection of strains that enhance pasture and turf production through better disease control.

The Impact of Aboveground Epichloë Endophytic Fungi on the Rhizosphere Microbial Functions of the Host Melica transsilvanica

“…The influence of Epichloë on the host in producing specific metabolites to resist pathogen invasion in both aboveground and belowground parts has been extensively studied [47]. In this study, the lower abundance and diversity of virulence factors enriched in the root zone of EI plants further corroborate this finding.…”

Antibacterial and antioxidant activity of endophytic fungi extracts isolated from the petiole of sungkai plant (Peronema canescens)

“…Extraction and isolation of endophytic fungal compounds are efficient due to the short cultivation time (Castro et al 2022;Elfita et al 2023;Oktiansyah et al 2023b;Singh et al 2021). The research results explain that the metabolites of fungal endophyte isolated from medicinal plants show that most of their secondary metabolites have unique chemical structures and can act as antimicrobial and antioxidants (Neamul Kabir Zihad et al 2022;Wen et al 2022;Fernando et al 2022;Tiwari and Bae, 2022;Xu et al 2021;Gautam 2014;Gautam et al 2013). Research on endophytic fungi isolated from the sungkai plant has also been reported, such as leaves, stems and roots.…”

Metabolic Potential of Epichloë Endophytes for Host Grass Fungal Disease Resistance

“…The screening methods are, however, limited to the "known known" alkaloids-the well described Epichloë-derived compounds referred to in Table 1. Of the novel endophytes described on Table 1 only two, Nea 12 and Nea 23, have been investigated for production of antifungal metabolites in vitro and in planta [36,37]. Thus, further research is required to investigate the 'known unknown' metabolites, such as those responsible for disease resistance, that are beneficial to the pasture and turf grass related industries [38].…”

“…With the availability of new high throughput technology, rigorous analytical methods are available to identify and quantify antimicrobial activity and detect the responsible molecules [73][74][75]. Early studies have shown the potential of Epichloë endophytes to inhibit pathogen infections, while more recent studies have focused on isolating and characterising responsible antimicrobial molecules [25,36,72].…”