The endophytic continuum

Area of Science:

• Plant Pathology
• Mycology
• Symbiotic Interactions

Background:

• The term 'endophyte' broadly covers plant-associated organisms, while 'fungal endophyte' specifically denotes fungi colonizing plants asymptomatically.
• Current understanding often captures a snapshot of the interaction, overlooking the dynamic nature of fungal endophyte-host relationships.

Purpose of the Study:

• To review literature on non-balansiaceous fungal endophytes colonizing plants without visible disease.
• To explore the continuum of physiological, developmental, and evolutionary aspects of fungal endophytes.
• To examine the nature of endophyte-host interactions, hypothesizing a balance of antagonisms.

Main Methods:

• Literature review of non-balansiaceous fungi involved in asymptomatic plant colonization.
• Analysis of fungal endophyte characteristics including infection, colonization, metabolism, and life-history strategies.
• Examination of fungal and host taxa involved in these symbioses.

Main Results:

• Fungal endophytes display a wide range of characteristics, forming a continuum in their interactions with host plants.
• Endophyte-host interactions are characterized by a balance of antagonisms, involving fungal virulence and host defense mechanisms.
• Fungal endophytes exhibit greater phenotypic plasticity than pathogens, allowing for diverse interaction outcomes.

Conclusions:

• All endophyte-host interactions involve a degree of antagonism, challenging the notion of neutral relationships.
• Fungal endophytes possess remarkable phenotypic plasticity, enabling varied strategies from colonization to pathogen-like behavior.
• This phenotypic plasticity is a key driver of fungal endophyte evolution.