Identification and breeding significance of translocated chromosomes in a Japanese common wheat [Triticum aestivum] variety Eshimashinriki

Translocated chromosomes in the common wheat variety Eshimashinriki were identified, and their transmission to Japanese varieties were investigated to evaluate their breeding significance. Pairing configurations were ex-amined at the first metaphase in monotelodisomic hybrids of Eshhnashinriki with Chinese Spring ditelosomics. Eshimashinriki was confirmed to contain two independent reciprocal translocations relative to Chinese Spring, one between chromosomes 4B and 6B and another of small segments between 3B and probably 7B. According to C-banding and pairing frequencies, the breakpoints in the translocation between 4B and 6B were identified to be within the centromeric regions, giving rise to T4BS · 6BL and T4BL· 6BS. The translocation between 4B and 6B originated in the local variety Shinriki and transmitted to Eshimashinriki in the course of its breeding. Furthermore, this translocation was transmitted from Eshimashinriki to 81 % of the tested 16 varieties. Among these varieties, Saikai 102 and 12 of Norin varieties had inherited this translocation through nine different breeding cross combinations. These results indicate that the translocation between 4B and 6B of Eshimashinriki has important breeding potential resulting in its preferential transmission and maintenance in different breeding crosses. Based on the information on these varieties, yellow rust resistance, and probably adaptability and yield-improvement genes are the most possible reasons for the wide spread of this translocation. Location of these genes at the proximal region of one or both arms of the translocated chromosomes, where recombination is very rare, would insure their segregation and selection as a block with the translocated chromosomes