http://ocasapiens-dweb.blogautore.repubblica.it/
orso castano: dunque l'epigenetica coinvolge anche le piante. Questo comporta analisi differenziali metodologiche e comparative, nonche' la costruzione di una visione scientifica sistemica , uomo-piante, tutta da costruire, anche importanti intuizioni in tal senso ci sono gia' state. Colpisce l'assenza di simili importanti considerazioniin chi studia l'epigenetica umana. Ma torneremo spesso su tale confronto/argomento
In Cortijo, S. et al. Mapping the Epigenetic Basis of Complex Traits (2014) Science
Evolution Plant Epigenetics
Express. Researchers from the University of Groningen Bioinformatics center, and their collaborators, have made the exciting discovery that epigenotypes in plants result in complex phenotypes that are stably inherited, and subject to selection.
The team prepared inbred Arabidopsis samples with the same genomes, but differing methylomes. Methyl-seq analysis showed that certain differentially methylated regions (DMRs) behave as quantitative trait loci (QTL epi). These QTL epi were demonstrated to be responsible for 60-90% of two complex traits, flowering time and primary root length. The same QTL epi were also found functioning in wildtype Arabidopsis.
Co-Team leader, Assistant professor Frank Johannes explains ‘We used the same method to locate regions in the DNA, not with different sequences but with different epigenetic marks that contribute to certain traits in the plant. This is a breakthrough, because it changes the way we view genetics. And it may even be of huge economic importance.
Abstract ’Quantifying the impact of heritable epigenetic variation on complex traits is an emerging challenge in population genetics. Here, we analyze a population of isogenic Arabidopsis lines that segregate experimentally induced DNA methylation changes at hundreds of regions across the genome. We demonstrate that several of these differentially methylated regions (DMRs) act as bona fide epigenetic quantitative trait loci (QTLepi), accounting for 60 to 90% of the heritability for two complex traits, flowering time and primary root length. These QTLepi are reproducible and can be subjected to artificial selection. Many of the experimentally induced DMRs are also variable in natural populations of this species and may thus provide an epigenetic basis for Darwinian evolution independently of DNA sequence changes.
From a plant evolution perspective, this new information could answer the controversial “problem of missing heritability”.
Integrative epigenomic mapping defines four main chromatin states in Arabidopsis
Abstract
...............Post-translational modification of histones and DNA methylation are important components of chromatin-level control of genome activity in eukaryotes. However, principles governing the combinatorial association of chromatin marks along the genome remain poorly understood. Here, we have generated epigenomic maps for eight histone modifications (H3K4me2 and 3, H3K27me1 and 2, H3K36me3, H3K56ac, H4K20me1 and H2Bub) in the model plant Arabidopsis and we have combined these maps with others, produced under identical conditions, for H3K9me2, H3K9me3, H3K27me3 and DNA methylation. Integrative analysis indicates that these 12 chromatin marks, which collectively cover ∼90% of the genome, are present at any given position in a very limited number of combinations. Moreover, we show that the distribution of the 12 marks along the genomic sequence defines four main chromatin states, which preferentially index active genes, repressed genes, silent repeat elements and intergenic regions. Given the compact nature of the Arabidopsis genome, these four indexing states typically translate into short chromatin domains interspersed with each other. This first combinatorial view of the Arabidopsis epigenome points to simple principles of organization as in metazoans and provides a framework for further studies of chromatin-based regulatory mechanisms in plants................
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