The Japanese Journal of Genetics

The number of chromosomes in Brassica has been reported by several authors. Since 1929 present writers also examined the chromosome number in 13 species of Brassica covering about one hundred cultivated varieties as the aid to the genetical work of the senior author.
The plants that provided the materials were raised from the seeds obtained from home and abroad. The smear method and sometimes the paraffin method were used. In the case of smear methed, the staining of BELLING's iron-aceto-carmine and HEITZ's aceto-carmine with acetic alcohol were used. Staining of the chromosomes was satisfactory with these stains.
For permanent preparations, CARNOY's fluids mostly and in a few cases NAWASCHIN's fluid were used as fixing reagent and HEIDENHAIN's iron-alum haematoxylin as stain.
The different varieties within the same species exhibited invariably an identical chromosome number. The haploid number of chromosomes is given as follows:
Brassica nigra, KOCH 8 Brassica arvensis, RABH. 9
B. oleracea, L. 9 B. campestris, L. 10
B. pekinensis, RUPR. 10 B. chinensis, L. 10
B. narinosa, BAILEY 10 B. rapa, L. 10
B. nipposinica, BAILEY 10 B. alba, RABH. 12
B. juncea, COSS. B. napiformis BAILEY 18
(including B. cernua, HEMSL.) 18
B. Napus, L. 19

View full abstract

Show abstractHide abstract

The somatic number of chromosomes has been determined in root-tip cells of various garden varieties of the polyanthus narcissus. The results obtained (including the results of my previous paper, 1929) are listed in the Japanese text p. 159 (Fig. 1a-g).
For the sake of convenience in description, I have named the four garden varieties of which the original name is doubtful, as follows:-“B₂₀” (the first mentioned variety in the list), “B₂₁” (the third variety in the list), “A₂₂” (the fourth variety) and “B₃₁” (the eighth variety). This nomenclature is based on BAKER'S classification. He has classified the polyanthus narcissus into three groups, “bicolores”, “albae”and “luteae”according to the difference in the colour of the collora (BAILEY 1917, p. 2112). By“B₂₀”is meant here that the plant is one belonging to the“bicolores”type and has 20 chromosomes in its somatic cells. In like manner, the letters A and B in the other cases also indicate that the plant belonging to the group which has the corresponding initial in its name, and the number at the foot of the letters signifies the somatic number of chromosomes which the plant carries.
In the present paper some results of observation of the meiotic phases in the pollen mother cells of the varieties with 20, 22, 30 and 32 chromosomes (2n) respectively are given.

View full abstract

Download PDF (585K)

Register with J-STAGE for free!