Studies on Chromosome Arrangement in Some Higher Plants

I. Interphase chromosomes in three liliaceous plants

Abstract

1.The mode of the chromosomal arrangement in interphase nuclei was investigated in the root tips of three liliaceous plants; Polygonatum lasianthum with large-, or medium-sized chromosomes (2n=20), Dianella ensifolia with relatively small-sized chromosomes (2n=32), and Tofieldia coccinea var. kondoi with smallsized chromosomes (2n=30). Both the C-banded and the unpressed preparations stained with aceto-orcein were used for this study.
2. After C-banding treatment, the centromeric regions of all the mitotic chromosomes and the regions of the secondary constriction were deeply stained. Most of these C-banded segments also appeared in interphase nuclei.
3. The centromeric regions tended to be located close to the inner surface of the nuclear envelope during the period from telophase to prophase.
4. The relative extent of the distributional range of the centromeric regions in the nucleus, which was considered to extend from the center of the polar region of the nucleus, was found to be nearly constant for each species but different distinctly among the three species examined: That is, the relative extent of the distributional range was the smallest in P. lasianthum, and the largest in T coccinea var. kondoi.
5. The mode of the chromosomal arrangement at telophase tended to be maintained during interphase and prophase.
6. The relationship between the relative extent of the distributional range of the centromeric regions in the nucleus and the variability of the relative positions of chromosomes during the mitotic cycle was discussed.