Figure 1.

Schematic repersentation of chromatin organization in Arabidopsis thaliana. Chromosomes territories are repersented with different colors, being two of chromosomes showed in detailed with the most relevant interactions, observed in previous 3C-derived analyses. Pericentromeric regions are recognized for establishing strong intra-and inter-chromosomal intreraction between them. Intreractive Heterochromatic Island (IHIs) can be found in different region along the five chromosomes arms and coverge in the three dimensional space, where they from a KNOT, or a superstructure that consist of inter and intra-chromosomal interaction of both long and short-range. Regulatory elements and genes belonging to the same chromosomes are comonly connected by the formation of loops or higher order chromatin structures. For instance, FLC expression is activated by the formation a gene loop between its 3′ and 5′ flanking region and H3K4 trimethylation along the locus. Moreover, chromatin loops encompassing different genes have also been involved in gene expression fine-tuning; the ragulation of the PID gene by the formation of a loop between PID and APOLO loci is a clear example of these structures. Ploidy level of the cell and genemic position of the intrective region shown above are not considerd.