Effect of the ph1b mutant on chromosome pairing in hybrids between Dasypyrum villosum and Triticum aestivum

Chromosome pairing was analysed in F-1 hybrids of the wheat cultivar 'Chinese Spring' (CS) and its ph1b mutant (CS ph1b) with Dasypyrum villosum. On average, 1.61 chromosomes per cell paired in the hybrid CS x D. Villosum, but 14.43 in the hybrid CS ph1b x D. villosum. Genomic fluorescence in situ hybridization (GISH) revealed three types of homoeologous association between wheat (W) and D. villosum (D) chromosomes (W-D, D-W-W and D-W-D) in pollen mother cells of the CS ph1b x D. villosum hybrid, and only one type (W-W), in the CS x D. villosum hybrid. Both F-1 hybrids were self-sterile. The seed set of the backcross of CS x D. villosum with CS was 6.67% and that of CS ph1b x D. villosum with CS or CS ph1b was only 0.45%. The chromosome number of BC, plants varied from 48 to 72. Translocations of chromosome segments or entire arms between wheat and D. villosum chromosomes were detected by GISH in the BC, plants from the backcross of CS ph1b x D. villosum to CS ph1b