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Summary: Although the 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.Transcriptome‐wide m6A methylome profiling revealed that m6A is mainly enriched in the coding sequence and 3′ untranslated region in response to drought stress in apple, by recognizing the plant‐specific sequence motif UGUAH (H=A, U or C). We identified a catalytically active component of the m6A methyltransferase complex, MdMTA. An in vitro methyl transfer assay, dot blot, LC‐MS/MS and m6A‐sequencing (m6A‐seq) suggested that MdMTA is an m6A writer and essential for m6A mRNA modification.Further studies revealed that MdMTA is required for apple drought tolerance. m6A‐seq and RNA‐seq analyses under drought conditions showed that MdMTA mediates m6A modification and transcripts of mRNAs involved in oxidative stress and lignin deposition. Moreover, m6A modification promotes mRNA stability and the translation efficiency of these genes in response to drought stress. Consistently, MdMTA enhances lignin deposition and scavenging of reactive oxygen species under drought conditions.Our results reveal the global involvement of m6A modification in the drought response of perennial apple trees and illustrate its molecular mechanisms, thereby providing candidate genes for the breeding of stress‐tolerant apple cultivars. [ABSTRACT FROM AUTHOR]

Although the N 6 -methyladenosine (m 6 A) modification is the most prevalent RNA modification in eukaryotes, the global m 6 A modification landscape and its molecular regulatory mechanism in response to drought stress remain unclear. Transcriptome-wide m 6 A methylome profiling revealed that m 6 A is mainly enriched in the coding sequence and 3' untranslated region in response to drought stress in apple, by recognizing the plant-specific sequence motif UGUAH (H=A, U or C). We identified a catalytically active component of the m 6 A methyltransferase complex, MdMTA. An in vitro methyl transfer assay, dot blot, LC-MS/MS and m 6 A-sequencing (m 6 A-seq) suggested that MdMTA is an m 6 A writer and essential for m 6 A mRNA modification. Further studies revealed that MdMTA is required for apple drought tolerance. m 6 A-seq and RNA-seq analyses under drought conditions showed that MdMTA mediates m 6 A modification and transcripts of mRNAs involved in oxidative stress and lignin deposition. Moreover, m 6 A modification promotes mRNA stability and the translation efficiency of these genes in response to drought stress. Consistently, MdMTA enhances lignin deposition and scavenging of reactive oxygen species under drought conditions. Our results reveal the global involvement of m 6 A modification in the drought response of perennial apple trees and illustrate its molecular mechanisms, thereby providing candidate genes for the breeding of stress-tolerant apple cultivars., (© 2022 The Authors. New Phytologist © 2022 New Phytologist Foundation.)