Molecular cytogenetic identification of a new synthetic amphiploid (Triticum timococcum, A^tA^tGGA^mA^m) with a seed setting rate comparable with that of natural Triticum zhukovskyi

Triticum timopheevii (A(t)A(t)GG) was previously cultivated in western Georgia, and Triticum zhukovskyi (A(t)A(t)GGA(m)A(m)) is a natural allohexaploid originating from hybridization of T. timopheevii and Triticum monococcum (A(m)A(m)). In this study, two synthetic amphiploids (Triticum timococcum, A(t)A(t)GGA(m)A(m)), Syn-A(t)GA(m)-20 and Syn-A(t)GA(m)-21, were developed by chromosome doubling of F-1 hybrids between T. timopheevii and T. monococcum. Chromosomes of these two amphiploids were identified by fluorescence in situ hybridization (FISH) utilizing oligonucleotide probes Oligo-pSc119.2-1, Oligo-pTa535-1, Oligo-pTa71-2 and Oligo-(AAC)(7). Each amphiploid had 42 chromosomes derived from its parents, but the Glu-A1(m)x subunits from einkorn were both not expressed. Syn-A(t)GA(m)-20 had low average seed setting rates of 19.86% and 20.50% in two different years, with abnormal spikes similar to those reported before. Syn-A(t)GA(m)-21 had normal spikes with average seed setting rates of 65.88% and 61.56% in two different years, comparable with those of natural T. zhukovskyi. However, the relationship between Syn-A(t)GA(m)-21 and natural T. zhukovskyi requires further study. This research provides new materials for studying the origin of T. zhukovskyi.