Dynamic changes in the morphology of barley chromosomes during the mitotic metaphase stage

Dynamic changes in the morphology of barley chromosomes during the mitotic metaphase stage were observed and attributed to the differential condensation of the chromosome arms. The mitotic stage of the 250 metaphase spreads was classified into five sub-stages from early metaphase to late metaphase. At each sub-stage, the relative length (RL) and the arm ratio (AR) of the chromosomes were examined and the ranking of the chromosomes for the two parameters was also determined for the respective chromosomal spreads. As a result, the RL and AR values of some of the chromosomes as well as their ranking for the two parameters were found to vary with the progression of the metaphase stage. The dynamic changes in the RL and AR values were closely related to the differences in the condensation rate of the chromosome arm. Factors involved in the differential chromosome condensation are discussed.