The Japanese common wheat cultivar Shirodaruma, a descendant from the landrace Daruma, is the ancestor of the donor of the semidwarfing genes, Norin 10. Breakpoints of translocations and translocated chromosomes were identified in Shirodaruma and Daruma, respectively. An amphihaploid plant containing telosome 4BS and the translocated chromosome 6B was isolated from the progeny of the cross
Shirodaruma/Chinese Spring ditelosomic 4BS//rye cv. At the first metaphase of this plant, the telosome 4BS was paired with the long arm of chromosome 6B forming a heteromorphic bivalent in 70.0% of the pollen mother cells. This indicates that the reciprocal translocation in Shirodaruma involved 4BS and 6BL. Southern hybridization of digested DNA from the isolated amphihaploid plant with probes having RFLP markers Xglk 661d and the centromere on 4BS and between Xglk 582 and 736 on 6BL, thus, gave rise to translocation chromosomes T4BL · 4BS: 6BL and T6BS · 6BL: 4BS. On the other hand, the isolated amphihaploid plant showed significantly high frequency of meiotic pairing between homoeologous chromosomes that was probably atributed to inhibition or imbalance in the normal Ph system of wheat. Telosomics and chromosomal banding analyses indicated that Daruma has translocation chromosomes T3AS · 7AS and T3AL · 7AL. Thus, Shirodaruma and ancestor Daruma carry different chromosomal translocations. This suggests that either the translocation in Daruma was restructured and a new one between 4B and 6B was formed in Shirodaruma or it is likely that the existing stock of Daruma and Shirodaruma were selected from an old landrace Daruma that was heterogeneous for both of these translocations.