Sizing the Genetic and Physical Centromere of Barley Chromosomes as a Prerequisite of Understanding Genome Evolution in the Genus Hordeum

Genome characterization of agricultural important species such as barley (Hordeum vulgare), requires knowledge of the correlation between the genetic and physical maps. Genetic maps are based on recombination values and often show different positions of molecular markers in comparison to physical maps, particularly in the centromere that is generally poor in meiotic recombinations.

In order to improve the resolution of the physical map of barley in the centromeric and pericentromeric regions we use fluorescence in situ hybridization (FISH) to order 100 repeat-free BAC-derived single-copy sequences that were genetically assigned to a 10 cM bin around the centromere of 3H of Hordeum vulgare. Single-copy probes have been generated by the Kmasker, a tool for in silico prediction of single-copy sequences for the large genome species using BACs as a template (Schmutzer et al., in press). Fifty contig-specific single-copy probes, with an average length of 7 kb, marked about 54% of chromosome 3H. Furthermore, the established order of these probes on barley chromosome 3H are being used to test their order in related Hordeum species and potentially other Triticeae.

Physical or cytological mapping of predefined sequences emerged as a feasible strategy to correct the discrepancy between physical and genetic centromere of barley chromosomes and will allow us to analyze the synteny of genus Hordeum.

Back to: Plant Cytogenetics

Previous Abstract | Next Abstract >>