The Behavior of an X-Ray-Induced Ring Chromosome in Maize

Abstract

The behavior of an X-ray-induced ring chromosome in maize involving almost the whole of chromosome 6 is described. By crossing over in ring-rod heterozygotes and breakage of the resultant anaphase bridges, the ring is frequently converted into a rod chromosome. Some of the rods carry a duplication and are transformed back to rings in subsequent meiotic divisions. The inclusion of the nucleolar organizer in the anaphase bridge results in a high frequency of aberrant spore quartet types.