Evolution of the RNA N 6-Methyladenosine Methylome Mediated by Genomic Duplication.

RNA N 6-methyladenosine (m6A) modification is the most abundant form of RNA epigenetic modification in eukaryotes. Given that m6A evolution is associated with the selective constraints of nucleotide sequences in mammalian genomes, we hypothesize that m6A evolution can be linked, at least in part, to genomic duplication events in complex polyploid plant genomes. To test this hypothesis, we presented the maize (Zea mays) m6A modification landscape in a transcriptome-wide manner and identified 11,968 m6A peaks carried by 5,893 and 3,811 genes from two subgenomes (maize1 and maize2, respectively). Each of these subgenomes covered over 2,200 duplicate genes. Within these duplicate genes, those carrying m6A peaks exhibited significant differences in retention rate. This biased subgenome fractionation of m6A-methylated genes is associated with multiple sequence features and is influenced by asymmetric evolutionary rates. We also characterized the coevolutionary patterns of m6A-methylated genes and transposable elements, which can be mediated by whole genome duplication and tandem duplication. We revealed the evolutionary conservation and divergence of duplicated m6A functional factors and the potential role of m6A modification in maize responses to drought stress. This study highlights complex interplays between m6A modification and gene duplication, providing a reference for understanding the mechanisms underlying m6A evolution mediated by genome duplication events.