MdMTA-mediated m6A modification enhances drought tolerance by promoting mRNA stability and translation efficiency of genes involved in lignin deposition and oxidative stress

Background: Although N6-methyladenosine (m6A) modification is the most prevalent RNA modification in eukaryotes, the global m6A modification landscape and its molecular regulatory mechanism in response to drought stress remain unclear. Results: Here, we found that m6A was mainly enriched in the CDS, stop codon, and 3′ UTR regions in response to drought stress in apple. We identified a catalytic active component of the m6A methyltransferase complex, MdMTA, that positively regulates drought tolerance in apple. In MdMTA RNAi plants, mRNA showed a global transcriptome-wide loss of m6A modification. Further study revealed that MdMTA mediated m6A modification of mRNAs that encode genes involved in oxidative stress and lignin synthesis. Moreover, m6A modification promoted the transcription of these genes in response to drought stress by positively regulating their mRNA stability. Meanwhile, m6A modification enhanced the translation efficiency of several genes, which m6A residues located near start codon. Consistently, MdMTA positively regulated ROS scavenging and lignin deposition under drought stress conditions. Conclusion: Our results reveal the involvement of m6A modification in drought tolerance of perennial apple trees and illustrate its molecular mechanisms, thereby providing candidate genes for the breeding of stress-tolerant apple cultivars.