BACKGROUND: The packaging of long chromatin fibres in the nucleus poses a major challenge, as it must fulfil both physical and functional requirements. Until recently, insight into the chromosomal architecture of plants was mainly provided by cytogenetic studies. Complementary to these analyses, chromosome conformation capture technologies promise to refine and improve our view on chromosomal architecture and to provide a more generalized description of nuclear organization.
RESULTS: Employing circular chromosome conformation capture, this study describes chromosomal architecture in Arabidopsis nuclei from a genome-wide perspective. Surprisingly, the linear organisation of chromosomes is reflected in the genome-wide interactome. In addition, we study the interplay of the interactome and epigenetic marks and report that the heterochromatic knob on the short arm of chromosome 4 (hk4s) maintains a pericentromere-like interaction profile and interactome despite its euchromatic surrounding.
CONCLUSION: Despite the extreme condensation that is necessary to pack the chromosomes into the nucleus, the Arabidopsis genome appears to be packed in a predictive manner, according to the following criteria: heterochromatin and euchromatin represent two distinct interactomes; interactions between chromosomes correlate with the linear position on the chromosome arm; and distal chromosome regions have a higher potential to interact with other chromosomes.