Stability of Repeated Sequence Clusters in Hybrids of Maize as Revealed by FISH
Previous studies of genome size in inbreds and hybrids had revealed that in some combinations the genome size in hybrids deviates from the midparent value of the parents. We examined whether repetitive sequence arrays such as knob heterochromatin, centromere repeats and ribosomal RNAs, as visualized cytologically in root tip chromosome spreads, would reveal any changes in copy number in such hybrids. The results indicate that no obvious changes in copy number are observed. Thus, the mechanisms by which repetitive arrays change copy number seem unrelated to the hybrid effect. Moreover, the hybrid genome effect is not manifested in gross changes in the most common repetitive sequences in the genome as determined in root tip spreads.
KeywordsMaize Repetitive sequences Knobs Heterochromatin rDNA Centromeres Genome size FISH