| Sumario: | The frequencies and lengths of drought periods are increasing in subtropical and tem-perate regions worldwide. Epigenetic responses to water stress could be key for plantresilience to these largely unpredictable challenges. Experimental DNA demethylation,together with application of a stress factor is an appropriate strategy to reveal the con-tribution of epigenetics to plant responses to stress.• We analysed leaf cytosine methylation changes in adult plants of the annual Mediterra-nean herb, Erodium cicutarium, in a greenhouse, after seed demethylation with5-Azacytidine and/or recurrent water stress. We used bisulfite RADseq (BsRADseq)and a newly reported reference genome for E. cicutarium to characterize methylationchanges in a 2 9 2 factorial design, controlling for plant relatedness.• In the long term, 5-Azacytidine treatment alone caused both hypo- andhyper-methylation at individual cytosines, with substantial hypomethylation in CGcontexts. In control conditions, drought resulted in a decrease in methylation in all butCHH contexts. In contrast, the genome of plants that experienced recurrent waterstress and had been treated with 5-Azacytidine increased DNA methylation level by ca.5%.• Seed demethylation and recurrent drought produced a highly significant interaction interms of global and context-specific cytosine methylation. Most methylation changesoccurred around genic regions and within Transposable Elements. The annotation ofthese Differentially Methylated Regions associated with genes included several with apotential role in stress responses (e.g., PAL, CDKC, and ABCF), confirming an epige-netic contribution in response to stress at the molecular level
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