N6-adenosine methylation of mRNA integrates multilevel auxin response and ground tissue development in Arabidopsis

Abstract

N6-methyl adenosine (m6A) is a widespread internal mRNA modification impacting the expression of numerous genes. Here we characterize the auxin-related defects among the pleiotropic phenotypes of the hypomorphic Arabidopsis thaliana mutants with the impaired status of m6A and present that they show strong resistance to exogenously applied auxin. By compiling major published m6A datasets, we propose that among the high-confidence target transcripts emerge those encoding the main components required for auxin signaling, including the auxin receptors TIR1/AFBs and ARF transcriptional regulators. We also observe subtle changes in endogenous levels of indole-3-acetic acid (IAA) metabolites in these hypomorphic lines, which correlate with the methylation status of the IAA amidohydrolase transcripts. In addition, we reveal that the reduced m6A levels lead to defects in the endodermal patterning in the primary root arising from the impaired timing of the periclinal cell divisions. These defects can be reverted by inhibition of auxin signaling. Together, our data underline that m6A likely affects the auxin-dependent processes at multiple levels.