Epigenetic Modifications, Immune Control Processes, and Plant Responses to Nematodes

Plants adapt to biotic and abiotic stresses through physiological, morphological, and genetic changes. In recent years, the fundamental roles of epigenetic mechanisms as regulators of various immune–biological processes in nematode–plant interactions have been increasingly recognized. Epigenetic control mechanisms include non-coding RNAs (ncRNAs), DNA methylation, and histone modifications. Gene expression and gene silencing play crucial roles in activated induced resistance during pathogen attacks. DNA methylation and histone modifications are linked to defense priming or immune memory, such as systemic acquired resistance (SAR). In addition, epigenetic processes play important roles in long-term defense priming, contributing to the development of immunological memory under future stress conditions. Therefore, advances in understanding epigenetic mechanisms hold considerable potential for future research on plant–nematode interactions. However, further development in the basic understanding of interactions among various stresses, the expansion of markers for epigenetic changes, and the permanence of priming are necessary to optimize its utilization in crop protection programs. In this paper, we focus on the function of epigenetic mechanisms in plant defense responses to nematode infection, specifically root-knot nematodes (RKNs). Understanding the adaptive ability of RKNs is important for developing suitable control methods. Additionally, we explore the role of epigenetic mechanisms in plant interactions with biological control agents.