Transcriptome-wide m⁶A methylation profile reveals tissue specific regulatory networks in switchgrass (Panicum...

The heavy metal cadmium (Cd), known for its high toxicity, poses a grave threat to human health through the food chain. N⁶-methyladenosine (m⁶A), the most abundant internal modification, regulates plant adaptation to various adversities, yet the panorama of m⁶A modifications in switchgrass under cadmium stress remains elusive. This study examines the physiological responses of switchgrass roots and shoots exposed to 50 μM CdCl₂, alongside an overview of transcriptome-wide m⁶A methylation patterns. After cadmium treatment, methylation modifications are primarily enriched near stop codons and the 3'UTR region, with a negative correlation between m⁶A modification and gene expression levels. In shoots, approximately 58 % of DEGs with m⁶A modifications show upregulation in expression and decrease in m⁶A peaks, including zinc transporter 4-like (ZIP4). In roots, about 43 % of DEGs with m⁶A modifications exhibit downregulation in expression and increase in m⁶A peaks, such as the ABC transporter family member (ABCG25). We further validate the m⁶A enrichment, gene expression and mRNA stability of ZIP4 in response to Cd treatment. The results suggest that the negative correlation of m⁶A enrichment and gene expression is due to altered mRNA stability. Our study establishes an m⁶A regulatory network governing cadmium transport in switchgrass roots and shoots, offering new avenues for candidate gene manipulation in phytoremediation applications of heavy metal pollution.