New Karyotype of Rumex acetosa L.

抄録

There was found a new karyotype in a diploid female clone of Rumex acetosa collected from Matsuyama city. The 12 autosomes (Fig. 1., I-XII) but two X-chromosomes were classified into five main groups. One consists of a large secondary-constricted chromosome (Ibid. III) by which the new karyotype is readily distinguishable from any other karyotype noted formerly. At prophase (Fig. 3), the outer segment adjacent to the secondary constriction (Ibid. III) is very darkly stained in contrast to the inner segment which is just as light as the short arm of ordinary subterminal-typed chromosome. Another group includes one small median-typed (Fig. 1, XI) and one small submedian-typed chromosome (Ibid. XII). At prophase, the former (Fig. 3, XI) has an outer region stained darkly in one arm, and such a dark region is lacking in the latter (Ibid. XII). It is probable that, as shown in Fig. 4, the secondary-constricted chromosome (Fig. 4, A) has arisen after the short arm of ordinary subterminal-typed chromosome (Ibid. B) had accepted the outer region stained darkly from one (Ibid. C) of two small median-typed chromosomes. The secondary constriction has not yet developed into a nucleolus organizer.