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Arabis alpina is a plant species of the Brassicaceae family that include more than 3,000 different species, among them, some economically important crops such are rape (canola), cabbage, mustard, etc. This study reveals the importance of the epigenome in genome evolution.
Researchers from the Center of Biotechnology and Genomics of Plants (CBGP) of the Polytechnic University of Madrid (UPM) have participated in the sequencing of the genome and epigenome of Arabis alpina. Making use of the most advanced techniques of genome and epigenome sequencing and bioinformatics, the authors have demonstrated that the genome of Arabis alpina spans 375 Mbp, almost three times bigger than that of Arabidopsis thaliana, a closely related species and until now the reference model plant of the Brassicaceae.
The reason for the bigger size of this genome is mainly due to the accumulation of transposons (mobile repeated sequences capable of autonomous replication in the genome). Transposons represent close to 50% of the nuclear DNA of Arabis alpina, while in the Arabidopsis thaliana these repeated sequences represent only 25% of this DNA.
Surprisingly, the data have revealed that in Arabis alpina, a perennial plant resistant to extreme temperatures, these transposable elements (DNA sequences that can change positions in the genome) are more abundant in the proximity of the chromosomal centromeres and their activity is determined by epigenetic modifications, such as, methylation of lysines in certain histones or a rare methylation of cytosines in the DNA. All these characteristics, unknown until now, emphasize the importance of the epigenome in the evolution of the Brassicaceae.
“Since Arabis alpina is a perennial species and it is resistant to extreme temperatures, this basic research could help in the future to design crops with these desirable traits that will probably be in high demand in the near future in order to feed an increasing world population (>9,000 million people expected in 2050) under non-optimal conditions due to the climate change”, explains Prof. Pilar Carbonero, principal investigator of the “Biotechnology and Genomic of Seeds” group of the CBGP (UPM).
This research, in which the group of Dr. Paz-Ares of the National Center of Biotechnology (CNB) of the Council for Scientific Research (CSIC), has also participated, has been the task of a trilateral international consortium (Germany, France, Spain) coordinated by Prof. G. Coupland of the Max Planck Institute (IMP) of Cologne (Köln, Germany), and in which other participant groups from the IMP-Tübingen, the INRA (Versailles-Grignon) and the CNRS-Paris have contributed.