7. An observation of chromosome 1-4 interchange in Nishimura's RT 3-11a

Institute of Botany, Academia Sinica, Nankang, Taipei, Taiwan 11529, ROC

The translocation series developed by Nishimura (1961) has been used extensively for genetic analysis in rice. Its relationship with chromosomes has been figured out by crossing each with trisomics, and the chromosomes were numbered arbitrarily (Nishimura 1961). By 1984, the interrelationships among trisomics, translocation and linkage groups have been worked out (Iwata and Omura 1975, 1984; Iwata et al. 1984). Cytological observations of chromosomes involved in the translocations would now be desired.

The seeds heterozygous for Nishimura's translocation series were made available through the courtesy of Drs. Iwata and Omura in 1985, and their cytological identification was initiated in our laboratory. In RT 3-11a, we found a ring of four at diakinesis and a cross configuration involving chromosomes 1 and 4 at pachytene. Observing its somatic prometaphase chromosomes, we could identify normal chromosomes 1 and 4 and those with translocation clearly, as shown Fig. 1. This agrees well with the result of trisomic analysis reported by Iwata and Omura (1984b, Table 3).

Fig. 1. Somatic prometaphase chromosomes observed in a heterozygote for RT 3-11a, in which chromosomes 1 and 4 are involved in translocations.


References

Iwata, N. and T. Omura, 1975. Studies on the trisomics in rice plants, III. Relation between trisomics and genetic linkage groups. Jpn. J. Breed. 25: 363- 368.

Iwata, N., H. Satoh and T. Omura, 1984. Studies on the trisomics in rice plants, V. Relationship between the twelve chromosomes and the linkage groups. Jpn. J. Breed. 3: 314-321.

Iwata, N. and T. Omura, 1984. Studies on the trisomics in rice plants, VI. An accomplishment of a trisomic series in japonica rice plants. Jpn. J. Genet. 59: 199-204.

Nishimura, Y., 1961. Studies on the reciprocal translocation in rice and barley. Bull. Nat. Inst. Agr. Sci., Japan, D9: 171-235. (Japanese/English)