Identification of differentially methylated regions (DMRs) associated
with leaf physiological acclimation to experimental long-term drought in
holm oak ( Quercus ilex L.)
Abstract
Shifts in rainfall patterns and increasing temperatures associated with
climate change are causing widespread forest decline, especially due to
the increase and duration of droughts. Tree species may have to quickly
adapt to these changing conditions, and epigenetic modifications are
expected to play a key role in regulating rapid acclimation responses.
In this study, we measured acclimation physiological responses and
methylome responses in mature holm oak trees ( Quercus ilex L.)
subjected to 15 years of experimental accrued drought (-29% of
rainfall) and their respective controls with ambient rainfall. We
hypothesized that: i) oak trees exposed to long-term drought will
exhibit different foliar traits due to adaptative phenotypic plasticity
to drought, ii) methylation levels will differ between the drought and
control trees allowing the identification of drought-induced
differentially methylated regions (DMRs), and iii) these DMRs correlate
with the differences in foliar traits. Our results confirmed all
hypotheses. The methylome analysis revealed 84 drought-related DMRs
among trees from different precipitation treatments, of which 17 DMRs
were significantly associated with measured phenotypic responses. This
study provides evidence of the role of epigenetic regulation for tree
acclimation responses in natural populations of holm oak facing
increased droughts and identified candidate genes potentially involved
in drought adaptation.