Variability in Chromomere Pattern in a Specific Chromosome Region at Pachytene

Abstract

The satellite region of maize chromosome 6 was examined for variability of chromomere pattern at pachytene in a large number of microsporocytes. The number of chromomeres visible with the light microscope in this region was found to vary from one to five in different cells from the same plant. The two homologues of the same cell usually, but not always, matched in chromomere pattern. It is emphasized that the common assumption that pachytene chromomeres are genetically constant from cell to cell is not justified and that alternative chromomere patterns may reflect differential aggregation during condensation of subunits.