Uncovering the Host Range-Lifestyle Relationship in the Endophytic and Anthracnose Pathogenic Genus <i>Colletotrichum</i>

Colletotrichum includes agriculturally and scientifically important pathogens that infect numerous plants. They can also adopt an endophytic lifestyle, refraining from causing disease and/or even promoting plant growth when inoculated on a non-susceptible host. In this manner, the host range of a Colletotrichum fungus can shift, depending on whether it exhibits endophytic or pathogenic lifestyles. Here, we aim to disentangle the relationship between lifestyle and host range in Colletotrichum. We discuss the ways in which pathogenic Colletotrichum species may act endophytically on alternative hosts, the molecular mechanisms underlying lifestyle, and the merits of using endophytic fungi alongside pathogenic fungi in research. In particular, we reference the Arabidopsis thaliana-Colletotrichum tofieldiae study system as a potential model for elucidating the dual roles of plant-fungus interactions, both beneficial and pathogenic, through integrative omics approaches and reverse genetics. This approach could identify key molecular targets for effective pathogen management in agriculture. Lastly, we propose an idea in which pathogenic lifestyle occupies a different host range than the endophytic lifestyle. This will enhance our understanding of pathogenicity and endophytism in a globally significant fungal genus and lays the groundwork for future research examining molecular determinants of lifestyle in plant-associated fungi.