Cytomolecular Analyses in Brachypodium and Their Role in Sequencing of B. stacei and B. hybridum Genomes

Cytomolecular analyses allow the study of nuclear genomes at the microscopic level. Together with resources developed during the Brachypodium distachyon genome sequencing project, such as deep and ordered BAC libraries, molecular cytogenetics provided an unprecedented opportunity to study the structure and evolution of grass genomes. Techniques, such as multicolour ‘barcoding’ of selected regions of individual chromosomes using BAC-FISH and specific painting of entire chromosomes, enabled not only precise identification and pattern of reorganisation of the chromosomes of various members of Brachypodium genus but even allowed detailed analyses of their arrangement during interphase. B. stacei (2n=20) and B. hybridum (2n=30) are two newly named species within the Brachypodium genus. Though previously considered to be autotetraploid and autohexaploid cytotypes of B. distachyon, respectively, in fact the former represents a distinct diploid species, and the latter is the allotetraploid hybrid between B. distachyon and B. stacei, with the chromosome number, genome size and many other features a combination of those seen in the two progenitors. This presentation outlines identification of B. stacei and B. hybridum chromosomes, which is a prerequisite to cytogenetically check the contigs constructed for those species in the future and their positioning along individual chromosomes using anchoring markers. Various current projects and future prospects for research are also briefly discussed. The authors acknowledge financial support from Polish Ministry of Science and Higher Education (grant N N303 570738). AB, NB and EB acknowledge scholarships from the UPGOW project co-financed by the European Social Fund.