G C A T T A C G G C A T genes Review The Chloroplast Epitranscriptome: Factors, Sites, Regulation, and Detection Methods Nikolay Manavski 1,† , Alexandre Vicente 1,†, Wei Chi 2 and Jörg Meurer 1,* 1 Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-University Munich, Großhaderner Street 2-4, 82152 Planegg-Martinsried, Germany;
[email protected] (N.M.);
[email protected] (A.V.) 2 Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China;
[email protected] * Correspondence:
[email protected]; Tel.: +49-89-218074556 † Both authors contributed equally to this work. Abstract: Modifications in nucleic acids are present in all three domains of life. More than 170 dis- tinct chemical modifications have been reported in cellular RNAs to date. Collectively termed as epitranscriptome, these RNA modifications are often dynamic and involve distinct regulatory pro- teins that install, remove, and interpret these marks in a site-specific manner. Covalent nucleotide modifications-such as methylations at diverse positions in the bases, polyuridylation, and pseu- douridylation and many others impact various events in the lifecycle of an RNA such as folding, localization, processing, stability, ribosome assembly, and translational processes and are thus cru- cial regulators of the RNA metabolism. In plants, the nuclear/cytoplasmic epitranscriptome plays important roles in a wide range of biological processes, such as organ development, viral infection, and physiological means. Notably, recent transcriptome-wide analyses have also revealed novel dynamic modifications not only in plant nuclear/cytoplasmic RNAs related to photosynthesis but Citation: Manavski, N.; Vicente, A.; especially in chloroplast mRNAs, suggesting important and hitherto undefined regulatory steps in Chi, W.; Meurer, J.