Epigenetic Regulation in Plant–Microbe Interaction and Plant Immunity

Interactions among organisms revolve around plants. Plants constantly interact with bacteria, nematodes, fungi, oomycetes, insects and other plants, either cooperatively or competitively. Plants are typically susceptible to a variety of harmful microorganisms since they are sessile. Over the course of the dynamic plant–pathogen interactions, pathogen effectors force plant mechanisms to evolve in a way that minimizes fitness costs by connecting pathogen detection to quick and efficient defense activation. In plants, histone modifications are one of the important markers for epigenetic regulation. The transcriptional reprogramming of plant immunity, microbial pathogenicity and their interactions are regulated by a variety of intricately linked changes. Noncoding small RNAs, DNA methylation, histone modification and chromatin remodelers are some of the regulatory elements involved in epigenetic regulation. The interaction among these elements and gene expression is precisely tuned, enabling plants to withstand harsh environmental changes and resist infection. In response to viral attack, plants generate small RNAs that silence the invading genome and establish intricate epigenetic regulatory systems, including chromatin remodeling, histone modifications and DNA methylation, to safeguard plants against infections. Certain plant recognition patterns enable plants to identify the microbial diseases, which in turn trigger a defense response. Recent research supports the significance of epigenetic modifications in plant immunity, particularly in the process of immunogenic memory development. In this chapter, we highlight the latest insights of epigenetic regulation in plant–microbe interaction and plant immunity. Moreover, we address certain new technologies that have the potential to significantly improve our understanding of these mechanisms in the future.