| Chromosomal aberrations induced by Agropyron
chromosome in common wheat Yasuhiko MUKAI Department of Biology, Osaka Kyoiku University, Ikeda, Osaka 563, Japan Four alloplasmic monosomic addition lines for the Agropyron chromosome were crossed with other common wheat cultivars, Chinese Spring and Salmon. The F1 seeds had poor germination. Some had slow germination and short roots, but the others were inviable. Mitotic cells from these short roots exhibited an extensive chromosomal aberrations, such as chromosomal fragments, telocentric, dicentric and ring chromosomes, translocations and chromosome mosaic (Fig. A). From Giemsa N-banding patterns of metaphase cells showing aberrations, breakage occurred in both eu- and heterochromatic regions, and break points on the chromosomes seem to be random (Fig. B). On the other hand, in metaphase cells from roots of the plants 60 days after germination, most had normal chromosome constitution and did not show any chromosomal aberrations. Cytological results also indicate that chromosomal aberrations occur in embryos and seedlings, and cells with aberrations tend to be selected in the successive nuclear divisions during young plants. Mitotic chromosome pairing data show that the used plants retained one Agropyron chromosome. Therefore, it can be concluded that at least aberrations were induced by gene(s) on the Agropyron chromosome. The chromosome rearrangement gene(s) may be useful for the induction of translocations between non-homologous chromosomes. This work was supported in part by a Grant-in-Aid (No. 59740307) from the Ministry of Education, Science and Culture, Japan. |