MEIOTIC ERRORS IN RYE RELATED TO CHIASMA FORMATION

Bridges and fragments at meiotic anaphase stages resulting from the spontaneous breakage and reunion of chromatids are common in genotypes of rye which are genetically unbalanced as a result of inbreeding or hybridisation. Similar configurations have been described in a variety of other plant and animal species, and ascribed to the same cause. Attention is drawn to the many similarities of the postulated breakage-reunion event to the exchange process involved in meiotic crossing-over, and the question is asked whether this anomalous behaviour could result from errors in crossing-over. Previous work employing different species having characteristically different and localised patterns of chiasma distribution has suggested the presence of a correlation between the distribution of chiasmata and the distribution of breakage-reunion events within bivalents. In the present investigation this approach has been followed, and extended, by comparing the distributions of breakage-reunion events in rye genotypes which have very different patterns of chiasma distribution. The results obtained indicate a marked similarity in the distribution patterns of these two events, suggesting that they are causally related and that they may therefore represent different manifestations of the same basic process. © 1968.