Abstract Description

Pathogenic fungi can cause disease, impacting crop yield and quality. Thus, is it essential to understand the mechanisms behind this plant-fungi interaction in search of possible strategies to mitigate and combat fungal pathogens. Marchantia polymorpha is a common liverwort with recent usage as a model species for studying early plant-microbe interactions. It has a short growth cycle and low genetic redundancy. This study is aimed to characterise pathogenic endophytic fungi and investigate the dynamics of infection in M. polymorpha. Endophytic pathogenic fungi were characterized morphologically and molecularly. Possible pathogenicity was determined by substrate range with different nitrogen and carbon sources, production of cell wall degrading enzymes and nutrient solubilisation. Plant-fungal interactions were assessed in M. polymorpha by examining the effects of plant biomass, cell viability, chlorophyll content, redox homeostasis – superoxide (O₂⁻), hydrogen peroxide (H₂O₂), Catalase (CAT), Superoxide dismutase (SOD) and Ascorbate peroxidase (APX), malondialdehyde content (MDA), confirming Koch’s postulates and lactophenol cotton blue staining. Macro, micro and ITS sequencing confirmed three isolates to be Fusarium equiseti, Fusarium foetens and Epiccocum viticis. Growth characterisation revealed that all isolates grew on carbon-rich media, while nitrogen utilisation varied: F. foetens grew on all nitrogen sources, whereas F. equiseti and E. viticis showed inhibited growth on ammonium-based media. Siderophore activity was observed in all isolates, with F. foetens showing the highest production. Enzymatic screening revealed positive amylase activity in E. viticis, while manganese production and tyrosinase activity were negative for all fungi. Infection assays using M. polymorpha confirmed Koch’s postulates, showing successful colonisation and visible disease symptoms. Growth reduction occurred in all treatments, with E. viticis causing the most severe necrosis and cell death. Chlorophyll content decreased globally for all three isolates. Biochemical analyses showed reduced O₂⁻ accumulation, while H₂O₂, MDA, CAT, and SOD remained near basal levels, indicating limited activation of oxidative stress responses. The distinct nutrient utilisation, enzymatic activities, and solubilisation activities observed among the isolates suggest certain metabolites may play a central role in their pathogenicity. Together, this work provides new insights into the functional diversity of endophytic phytopathogens and establishes a foundation for future studies on host defence mechanisms and fungal infection strategies.