Non-coding RNAs in Epigenetic Regulation

Although sessile in nature, plants have the flexibility to adapt to varying environmental stimuli. The epigenetic modulations are heritable modifications in gene expression that do not influence the DNA sequence. These reversible changes contribute to plant adaptability to fluctuating environmental conditions. Modifying gene expression in plants facilitates the regulatory mechanisms for stress tolerance. The eukaryotic transcriptome has a considerable portion of the non-coding RNA (ncRNAs). Throughout the life span of plants, various types of ncRNAs play crucial roles in regulating gene expression, thereby aiding plant plasticity. Epigenetic regulation has been linked to various classes of ncRNAs like small ncRNAs – microRNAs and small interfering RNAs, intermediate-sized RNAs like small nucleolar RNAs and small nuclear RNAs, and long ncRNAs. The sequence similarity between the ncRNAs and the transposable elements has been linked to neofunctionalization-mediated increased plasticity. ncRNA-mediated epigenetic silencing has been attributed to initiating various signaling pathways and increased plant stress response. The interaction of ncRNAs with chromatin modulators influences the DNA methylation patterns and histone modifications, inducing controlled gene regulation. The chapter addresses the involvement of significant classes of ncRNAs in the transcriptional processes, gene silencing, interaction with nucleic acid-binding proteins and their effect on epigenetic regulation. Through a systemic review, this chapter intends to unveil the complexity and significance of ncRNAs in determining the epigenetic landscape. Understanding these underlying mechanisms will provide new insights into developing stress-tolerant and nutritionally enhanced plants.