Plant ecological epigenetics
The
DNA sequence does not carry all the information required to determine
the phenotype of an organism. Epigenetics studies phenotypic variation
that is not accompanied by changes in DNA sequence, but involves a
variety of reversible chemical modifications that occur on the DNA and
on its interacting proteins, and impinge on chromatin structure. Such
epigenetic mechanisms contribute to complex traits and proper organism's
development.
In plants, DNA cytosine methylation is an important and complexly
regulated epigenetic mechanism involved in the response to several
environmental factors. Our understanding of its role in ecological
adaptation and evolutionary change is still vague and Ecological
Epigenetics studies should merge ecological experimental design with
appropriate molecular analyses to elucidate the contribution of
epigenetics to both phenotypic variation of wild plants and their
functional responses to rapid environmental changes (see Richards et al. 2017 for a review).
Along this line, our studies have contributed to illustrate extensive
variation in global methylation level across plant species, and
significant variation in methylation patterns of wild plant
populations, frequently exceeding genetic variation (Herrera & Bazaga 2010, Medrano et al. 2020).
Across species, global methylation spanned a 10-fold range (4 and 40 %,
aprox.) and is evolutionary related to monoploid genome size (Alonso et al. 2016).
Further, our studies suggested that the genomes of tropical species are
on average less methylated than those of Mediterranean ones, and woody
plants have genomes with lower methylation than perennial herbs (link
to Alonso et al. 2019).
At intraspecific level, we have related the extensive natural
epigenetic variation to impact of biotic stress imposed by herbivores (Herrera & Bazaga 2011, Herrera & Bazaga 2013) and abiotic factors such as drought (Medrano et al. 2014; see also Alonso et al. 2016 for a literature review).
Heritability across generations of such epigenetic marks (Herrera et al 2013, Herrera et al. 2018) and the strength of the relationship between genetic and epigenetic variation of wild populations (Herrera et al. 2016)
are two key issues that should be analysed more deeply in order to
better calibrating the impact of epigenetics in adaptation of wild
plant populations (Herrera et al. 2017).
Most recently, we have also documented the relevance of within-plant
epigenetic mosaicism and its relationship with reproductive output (Alonso et al 2018, Herrera et al. 2019), and plant-animal interactions (Herrera et al. 2019).
We take part of EPIDIVERSE (www.epidiverse.eu),
a Marie Skłodowska-Curie Innovative Training Network joining academic
groups from plant ecology, molecular (epi)genetics and bioinformatics
with life science companies to explore epigenetic mechanisms and their
adaptive relevance in natural plant populations of species with
different life-histories. We focused on epigenetic changes associated
to herbivory.
Our current projects seek to understand the links between genetic,
epigenetic and phenotypic variation in plants growing in harsh and
unpredictable environments like Mediterranean mountains (Balao et al. 2018 , Medrano et al. 2020) and their relevance for plant-animal interactions.