A VIM2/4 deletion, and premature truncations of CMT2 and FBX5, drive DNA methylation changes after colonization of a novel habitat

Abstract

DNA methylation is important to maintain genome stability, but alterations in genome-wide methylation patterns can produce widespread genomic effects, with the potential to facilitate rapid adaptation. Here we investigate DNA methylation evolution in Arabidopsis thaliana during its colonization of the drought-prone Cape Verde Islands (CVI). We identified three high-impact changes in genes linking histone modification to DNA methylation that underlie variation in DNA methylation within CVI. We show that gene body methylation is reduced in CVI relative to the Moroccan outgroup due to a 2.7-kb deletion between two VARIANT IN METHYLATIONgenes (VIM2and VIM4), causing aberrant expression of the VIM2/4 homologues. Disruptions of CHROMOMETHYLASE 2 (CMT2) and a newly identified DNA methylation modulator, F-BOX PROTEIN 5 (FBX5), which we validated using CRISPR mutant analysis, contribute to DNA methylation of transposable elements within CVI. Overall, our results reveal rapid methylome evolution driven largely by high-impact variants in three genes. This study shows that Arabidopsis thaliana colonizing the Cape Verde Islands rapidly evolved altered DNA methylation patterns through high-impact mutations affecting VIM2/4, CMT2 and FBX5, linked to alternative drought adaptation strategies.