In search of the mRNA modification landscape in plants

Precise regulation of gene expression is indispensable for the proper functioning of organisms in both optimal and challenging conditions. The most commonly known regulative mechanisms include the modulation of transcription, translation and adjustment of the transcript, and protein half-life. New players have recently emerged in the arena of gene expression regulators - chemical modifications of mRNAs.

The latest studies show that modified ribonucleotides affect transcript splicing, localization, secondary structures, interaction with other molecules and translation efficiency. Thus far, attention has been focused mostly on the most widespread mRNA modification - adenosine methylation at the N⁶ position (m⁶A). However, initial reports on the formation and possible functions of other modified ribonucleotides, such as cytosine methylated at the 5' position (m⁵C), 8-hydroxyguanosine (8-OHG) and 8-nitroguanosine (8-NO₂G), have started to appear in the literature. Additionally, some reports indicate that pseudouridine (Ψ) is present in mRNAs and might perform important regulatory functions in eukaryotic cells. The present review summarizes current knowledge regarding the above-mentioned modified ribonucleotides (m⁶A, m⁵C, 8-OHG, 8-NO₂G) in transcripts across various plant species, including Arabidopsis, rice, sunflower, wheat, soybean and potato.

Chemical modifications of ribonucleotides affect mRNA stability and translation efficiency. They thus constitute a newly discovered layer of gene expression regulation and have a profound effect on the development and functioning of various organisms, including plants.