Fixation of translocation 2A center dot 4B infers the monophyletic origin of Ethiopian tetraploid wheat

Analysis of structural chromosomal polymorphism revealed the presence of a previously reported 2A.4B translocation common to all 15 strains of Ethiopi an tetraploid wheat examined. Using the C-banding technique, we found two n ew translocations, T1B.6B and T5B.6B, and a pericentric inversion of chromo some 5A. The C-banding pattern indicated that in all three translocations t he breakpoint was located in the centromeric region. Sequential N-banding a nd genomic in situ hybridization (GISH) confirmed the location of the break point of translocation 2A.4B, and revealed that the breakpoint of another k nown translocation, 2A-2B, was in the proximal region of 2BL. The fixation of the 2A.4B translocation indicates the monophyletic origin of Ethiopian t etraploid wheat and the presence of a very severe bottleneck effect during its dispersal.