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 <i>Hordeum vulgare </i>(<i>Hv</i>) with their homoeologous arms of <i>H. bulbosum </i>(<i>Hb</i>) at metaphase I of meiosis in tetraploid <i>Hb </i>× <i>Hv </i>hybrids and the frequencies of recombined <i>Hv</i> chromosome arms in selfed offspring were studied on differentially visualized chromosomes after fluorescent in situ hybridisation. The frequencies of paired <i>Hv-Hb</i> arms in the F₂ and F₃ hybrids were correlated with the frequencies of recombined <i>Hv</i> chromosomes in progenies. Self-generation of hybrids, the number of <i>Hv</i> and <i>Hb</i> chromosomes, and the number of recombined <i>Hv</i> chromosomes of the hybrids strongly influenced the <i>Hv</i>-<i>Hb</i> pairing frequency in meiosis. Within the offspring of F₂ and F₃ hybrids both <i>Hv</i> 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.