Abstract:The karyotype of the primary wheat-wheatgrass disomic addition line TAI-14 was 2n = 44 in which all of the chromosomes were metacentric and submetacentric. However, in the progeny of the TAI-14, a pair of telocentric chromosomes were observed. In order to clarify whether the telocentric chromosomes were of common wheat or of wheatgrass, the fluorescence in situ hybridization (FISH) technique was employed. It was revealed that the wheat chromosomes exhibited red fluorescence while the ditelocentric chromosomes green fluorescence. Therefore, the primary TAI-14 was conversed from the disomic addition line into the ditelocentrie addition line. The possible explanation for such a variation and the potential significance of the ditelocentric addition line were discussed briefly.