MTA, an RNA m6A Methyltransferase, Enhances Drought Tolerance by Regulating the Development of Trichomes and Roots in Poplar

Abstract

N6-methyladenosine (m⁶A) is the most prevalent internal modification present in the mRNAs of all higher eukaryotes, where it is present within both coding and noncoding regions. In mammals, methylation requires the catalysis of a multicomponent m⁶A methyltransferase complex. Proposed biological functions for m⁶A modification include pre-mRNA splicing, RNA stability, cell fate regulation, and embryonic development. However, few studies have been conducted on m⁶A modification in trees. In particular, the regulation mechanism of RNA m⁶A in <i>Populus</i> development remains to be further elucidated. Here, we show that PtrMTA (<i>Populus trichocarpa</i> methyltransferase) was colocalized with PtrFIP37 in the nucleus. Importantly, the <i>PtrMTA</i>-overexpressing plants significantly increased the density of trichomes and exhibited a more developed root system than that of wild-type controls. Moreover, we found that <i>PtrMTA</i>-overexpressing plants had better tolerance to drought stress. We also found <i>PtrMTA</i> was a component of the m⁶A methyltransferase complex, which participated in the formation of m⁶A methylation in poplar. Taken together, these results demonstrate that <i>PtrMTA</i> is involved in drought resistance by affecting the development of trichomes and roots, which will provide new clues for the study of RNA m⁶A modification and expand our understanding of the epigenetic molecular mechanism in woody plants.