Segmental interchanges in barley

The positions of the breakpoints of 20 translocations in barley involving chromosomes 5 and 6 are proposed. For this work three sets of data were used: diakinesis or metaphase I configurations, stainable pollen of diallel crosses and the karyotype of the translocation heterozygotes. In three translocations the breakpoints are in the short arm of chromosome 5 and in the short arm or the satellite of chromosome 6; in four translocations in the short arm of chromosome 5 and in the long arm of chromosome 6; in three translocations in the long arm of chromosome 5 and in the short arm of chromosome 6; in ten translocations in the long arm of chromosome 5 and in the long arm of chromosome 6. Breakpoints seem to be at random and the frequency depends on the length of the chromosome arms involved. The possible occurrence of breakpoints in the centromere is also discussed.