The SWI/SNF subunit SWI3B functions with the m ⁶ A writer complex to establish embryo patterning in Arabidopsis

<jats:p> N <jats:sup>6</jats:sup> -methyladenosine (m <jats:sup>6</jats:sup> A) is the most abundant mRNA modification in eukaryotes and is essential for Arabidopsis embryogenesis. However, how m <jats:sup>6</jats:sup> A mRNA methylation is coordinated with other regulatory pathways during development including embryogenesis remains largely unknown. Here, we report the SWI/SNF chromatin-remodeling subunit SWI3B as a bona fide interactor of the m <jats:sup>6</jats:sup> A methyltransferase MTA. Like m <jats:sup>6</jats:sup> A writer mutants, SWI3B is required for early embryo development. We demonstrate that the interaction between MTA and SWI3B is required for MTA function during embryogenesis. MTA and SWI3B are both required to establish the correct expression pattern of WOX8 and proper auxin maxima during early embryogenesis. Transcriptome analysis of isolated embryos from <jats:italic>mta</jats:italic> , <jats:italic>swi3b</jats:italic> , and <jats:italic>fip37</jats:italic> mutants identified a shared set of upregulated transcripts, including STM as well as several NAC and ERF transcription factors that are normally absent or expressed at very low levels during early embryogenesis. Embryo-specific overexpression of <jats:italic>ANAC087</jats:italic> and <jats:italic>ERF114</jats:italic> genes phenocopied early embryonic defects observed in <jats:italic>mta</jats:italic> and <jats:italic>swi3b</jats:italic> mutants, indicating that their ectopic expression contributes to the observed developmental phenotype. Moreover, SWI3B and MTA are both required for m <jats:sup>6</jats:sup> A deposition on specific developmental transcripts. Together, our findings uncover a mechanism by which chromatin remodeling and m <jats:sup>6</jats:sup> A-mediated RNA regulation cooperate to suppress the precocious stability of key developmental regulators, thereby contributing to the establishment of the transcriptional program required for early embryo patterning in Arabidopsis. </jats:p>