MTA, an RNA m(6)A Methyltransferase, Enhances Drought Tolerance by Regulating the Development of Trichomes and Roots in Poplar

N6-methyladenosine (m(6)A) 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 m(6)A methyltransferase complex. Proposed biological functions for m(6)A modification include pre-mRNA splicing, RNA stability, cell fate regulation, and embryonic development. However, few studies have been conducted on m(6)A modification in trees. In particular, the regulation mechanism of RNA m(6)A in Populus development remains to be further elucidated. Here, we show that PtrMTA (Populus trichocarpa methyltransferase) was colocalized with PtrFIP37 in the nucleus. Importantly, the PtrMTA-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 PtrMTA-overexpressing plants had better tolerance to drought stress. We also found PtrMTA was a component of the m(6)A methyltransferase complex, which participated in the formation of m(6)A methylation in poplar. Taken together, these results demonstrate that PtrMTA is involved in drought resistance by affecting the development of trichomes and roots, which will provide new clues for the study of RNA m(6)A modification and expand our understanding of the epigenetic molecular mechanism in woody plants.