A CYTOGENETICALLY BASED PHYSICAL MAP OF CHROMOSOME-1B IN COMMON WHEAT

We have constructed a cytogenetically based physical map of chromosome 1B in common wheat by utilizing a total of 18 homozygous deletion sto cks. It was possible to divide chromosome 1B into 17 subregions. Ninet een genetic markers are physically mapped to nine subregions of chromo some 1B. Comparison of the cytological map of chromosome 1B with an RF LP-based genetic linkage map of Triticum tauschii revealed that the li near order of the genetic markers was maintained between chromosome 1B of hexaploid wheat and 1D of T. tauschii. Striking differences were o bserved between the physical and genetic maps in relation to the relat ive distances between the genetic markers. The genetic markers cluster ed in the middle of the genetic map were physically located in the dis tal regions of both arms of chromosome 1B. It is unclear whether the i ncreased recombination in the distal regions of chromosome 1B is due t o specific regions of increased recombination or a more broadly distri buted increase in recombination in the distal regions of Triticeae chr omosomes.