Supplementary Material for: The Effect of Homoeologous Meiotic Pairing in Tetraploid Hordeum bulbosum L. × H. vulgare L. Hybrids on Alien Introgressions in Offspring

The pairing behaviour of the individual chromosome arms of Hordeum vulgare (Hv) with their homoeologous arms of H. bulbosum (Hb) at metaphase I of meiosis in tetraploid Hb × Hv hybrids and the frequencies of recombined Hv
chromosome arms in selfed offspring were studied on differentially
visualized chromosomes after fluorescent in situ hybridisation. The
frequencies of paired Hv-Hb arms in the F2 and F3 hybrids were correlated with the frequencies of recombined Hv chromosomes in progenies. Self-generation of hybrids, the number of Hv and Hb chromosomes, and the number of recombined Hv chromosomes of the hybrids strongly influenced the Hv-Hb pairing frequency in meiosis. Within the offspring of F2 and F3 hybrids both Hv plants and hybrids were detected. In contrast, all progenies of the F4
hybrid were hybrids which exhibited centromere misdivisions. The
highest frequencies of homoeologous pairing in hybrids and most
recombinants were obtained for the barley chromosome 1HL. Recombinants
for 4HL, 5HS, 6HS, and 7HS were rarely found. Meiotic pairing and
recombinants involving chromosome 1HS were never observed. The results
of this study demonstrate that fertile tetraploid interspecific hybrids
with a high intergenomic pairing at meiosis are valuable basic material
for introgression breeding in barley.