The role of epigenetics in shaping plant-mycorrhizal interactions and ecosystem resilience

Plants establish environmental connections through mycorrhizal symbiosis. These relationships enable them to obtain nutrients and cope with stress while simultaneously exchanging information through subterranean networks. A unified understanding of the molecular mechanisms underlying mycorrhizal interactions that drive adaptation and survival has not yet been achieved, in part because research on them stems from diverse fields of research, such as mycorrhizal ecology and plant epigenetics. This review presents recent studies demonstrating that epigenetic control serves as a central system enabling plants to adapt and maintain stable relationships with mycorrhizal fungi. We begin by describing different types of mycorrhizae. We then analyze mycorrhizal symbiosis by integrating plant and fungal genomic data with molecular evidence on DNA methylation, histone modification, chromatin remodeling, and small RNA pathways. We demonstrate that mycorrhizal symbiosis depends on changing chromatin states, which influence the regulation of the establishment, maintenance, and efficiency of symbiotic connections. They also regulate the balance between nutrient uptake and defense. They may underlie mycorrhizal stress and transgenerational "memory." We review studies showing that RNA interference between different species enables reorganization of gene expression between plant and fungal cells. Finally, we identify key knowledge gaps and propose future research directions aimed at discovering reliable markers of mycorrhizal responses for epi-breeding and the development of climate-resilient agroecosystems.