Synaptonemal complex formation in rye (Secale cereale) heterozygous for telomeric C-bands

Zygotene–pachytene nuclei from a rye line heterozygous for most terminal C-bands were found by electron microscopic spreading analysis to have unequal lateral elements at most synaptonemal complex telomeres. An unpaired lateral element protruded beyond the end of the synaptonemal complex at each such telomere. Another rye line with only one C-band heterozygous telomere had only one uneven synaptonemal complex telomere. The length differences between paired lateral elements in heterozygotes (both total complement and individual synaptonemal complexes) was considerably less than the difference in DNA content or somatic metaphase chromosome size between C-band positive and C-band negative lines. There was no evidence of a synaptic adjustment effect reducing the telomere length differences in later pachytene–diplotene stage nuclei. Heterozygosity for the 1RL terminal C-band resulted in a slight reduction in chiasma frequency in that arm but no shift in chiasma position.Key words: rye, C-bands, telomeres, chromosome pairing, synaptonemal complex.