Synaptic abnormalities in spread nuclei of Secale. I. Inbred lines

The meiotic behaviour at metaphase I of two inbred lines of Secale cereale showed a decrease in the frequency of bound arms and the presence of univalents. The study of synaptonemal complex formation revealed that these inbred lines had asynapsis and many nuclei did not complete the pairing process. Synaptic abnormalities such as fold-back loops, short pairing partner switches, interstitial nonhomologous pairing regions, and asynchrony between bivalents were associated and correlated with interlocking. It is suggested that the asynapsis is due to a failure in the interlocking repair. All these abnormalities could affect the formation and maintenance of chiasmata and so could explain the metaphase I behaviour of these inbred lines and the differences between them.