Epitranscriptomics: An Additional Regulatory Layer in Plants' Development and Stress Response.

Epitranscriptomics has added a new layer of regulatory machinery to eukaryotes, and the advancement of sequencing technology has revealed more than 170 post-transcriptional modifications in various types of RNAs, including messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA (rRNA), and long non-coding RNA (lncRNA). Among these, N6-methyladenosine (m 6 A) and N5-methylcytidine (m 5 C) are the most prevalent internal mRNA modifications. These regulate various aspects of RNA metabolism, mainly mRNA degradation and translation. Recent advances have shown that regulation of RNA fate mediated by these epitranscriptomic marks has pervasive effects on a plant's development and responses to various biotic and abiotic stresses. Recently, it was demonstrated that the removal of human-FTO-mediated m 6 A from transcripts in transgenic rice and potatoes caused a dramatic increase in their yield, and that the m 6 A reader protein mediates stress responses in wheat and apple, indicating that regulation of m 6 A levels could be an efficient strategy for crop improvement. However, changing the overall m 6 A levels might have unpredictable effects; therefore, the identification of precise m 6 A levels at a single-base resolution is essential. In this review, we emphasize the roles of epitranscriptomic modifications in modulating molecular, physiological, and stress responses in plants, and provide an outlook on epitranscriptome engineering as a promising tool to ensure food security by editing specific m 6 A and m 5 C sites through robust genome-editing technology.