RNA N⁶-Methyladenosine Affects Copper-Induced Oxidative Stress Response in Arabidopsis thaliana

Recently, post-transcriptional regulation of mRNA mediated by N⁶-methyladenosine (m⁶A) has been found to have profound effects on transcriptome regulation during plant responses to various abiotic stresses. However, whether this RNA modification can affect an oxidative stress response in plants has not been studied. To assess the role of m⁶A modifications during copper-induced oxidative stress responses, m⁶A-IP-seq was performed in Arabidopsis seedlings exposed to high levels of copper sulfate. This analysis revealed large-scale shifts in this modification on the transcripts most relevant for oxidative stress. This altered epitranscriptomic mark is known to influence transcript abundance and translation; therefore we scrutinized these possibilities. We found an increased abundance of copper-enriched m⁶A-containing transcripts. Similarly, we also found increased ribosome occupancy of copper-enriched m⁶A-containing transcripts, specifically those encoding proteins involved with stress responses relevant to oxidative stressors. Furthermore, the significance of the m⁶A epitranscriptome on plant oxidative stress tolerance was uncovered by assessing germination and seedling development of the mta (N⁶-methyladenosine RNA methyltransferase A mutant complemented with ABI3:MTA) mutant exposed to high copper treatment. These analyses suggested hypersensitivity of the mta mutant compared to the wild-type plants in response to copper-induced oxidative stress. Overall, our findings suggest an important role for m⁶A in the oxidative stress response of Arabidopsis.