Figure 1.—

Rye-specific DNA sequences in centromeres of wheat and rye chromosomes and their arrangement at early meiosis. (A) Bivalents 2Brc–2Brc and 2B–2Brc at MI with rye centromeres labeled with probe pAWRC.1. Signals of the pSc119.2 probe identify B-genome chromosomes. (B) Rye centromere in univalents 2Brc and 2R at MI; chromosome 2R shows the location of the rye-specific pSc74 DNA repeat. (C) Nuclei at early leptotene (EL), leptotene–zygotene transition (LLEZ), late zygotene (LZ), and pachytene (P) of homozygotes 2Brc–2Brc and double monosomic 2Brc–2R. Homologous centromeres of rye (arrows) are separated in EL and LZ and associated in LLEZ and P, respectively. Wheat centromeres and telomeres were labeled with the 6C6 and pAtT4 DNA probes, respectively. (D) Frequency of associations of homologous rye centromeres in pairs 1Brc–1Brc, 2Brc–2Brc, and 2Brc–2R at EL, LLEZ, mid-zygotene (MZ), LZ, and P stages in Ph1+ and Ph1− wheat lines. Mean number of PMCs, n = 43 ± 3. Bars, 10 μm.