<italic>N</italic><italic>6</italic>-methyl-adenosine level in <italic>Nicotiana tabacum</italic> is associated with tobacco mosaic virus.

Background: <italic>N</italic>^{<italic>6</italic>}-methyl-adenosine (m⁶A) is a prevalent RNA modification in many species. Abnormal m⁶A methylation levels can lead to RNA dysfunction and can cause diseases. Tobacco mosaic virus (TMV) is one of the most devastating viruses for agricultural plants. It has many hosts, particularly including tobacco and other members the family Solanaceae. However, it remains unclear whether the abnormal growth induced by TMV is associated with the m⁶A level. Methods: A rapid and accurate analytical method using ultra-high-performance liquid chromatography coupled with high-resolution tandem mass spectrometry (UHPLC−HR − MS/MS) was developed to analyse the adenosine (A), cytidine (C), guanosine (G), uridine (U), and m⁶A contents in the tobacco leaf, and the m⁶A/G ratio was used to evaluate the m⁶A level. Subsequent protein sequence alignments were used to find the potential methylases and demethylases in <italic>Nicotiana tabacum</italic> (<italic>N. tabacum</italic>)<italic>.</italic> Finally, reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) was used to analyse the gene expression levels of the potential methylases and demethylases in the <italic>N. tabacum</italic> leaf. Results: The results showed that TMV reduced the m⁶A level. Moreover, protein sequence alignments revealed partial homology among human ALKBH5, <italic>Arabidopsis</italic> (NP_001031793), and <italic>Nicotiana sylvestris</italic> (XP_009800010). The gene expression level of the potential demethylase XM_009801708 increased at 14 and 21 days in <italic>N. tabacum</italic> infected with TMV, whereas all of the potential methylases decreased. Conclusions: The reversible m⁶A modification in <italic>N. tabacum</italic> mRNA might represent a novel epigenetic mechanism involved in TMV. [ABSTRACT FROM AUTHOR]