Plant endophytic fungi against plant-parasitic nematodes: from direct antagonism to plant-mediated biocontrol

Abstract

Plants have evolved sophisticated and tightly regulated immune systems to defend themselves against pathogen, whereas pathogens have developed diverse strategies to evade or manipulate host defenses. Plant-parasitic nematodes pose a particular challenge because of their intimate and prolonged interactions with host tissues, during which they actively manipulate plant physiology and immune responses. The limitations of conventional nematode control strategies have increased interest in plant-associated microorganisms as sustainable alternatives. Among these, endophytic fungi are emerging as promising allies because they can act through complementary mechanisms, combining direct antagonism of nematodes with the ability to modulate and prime plant immunity. This review integrates current knowledge on plant-nematode interactions with emerging insights into the role of endophytic fungi as modulators of plant defense. We examine how fungal endophytes influence hormone signaling, defense-related pathways, systemic resistance, and other components of plant immunity, while also considering their direct effects on nematode survival, development, and reproduction. We demonstrate that the protective potential of endophytic fungi extends beyond direct biocontrol and involves a broader reprogramming of plant responses that can enhance resistance to nematode attack. Finally, we discuss the factors that determine the consistency of these interactions, including fungal and plant genotype, environmental conditions, and the physiological and ecological context of the plant–fungus–nematode interaction. Understanding these mechanisms will be critical for translating endophyte-mediated plant protection into reliable and sustainable strategies for nematode management.