| Preliminary report on variation of chromosome constitution
in cultured cells of different lines of Chinese Spring wheat H. ASAMI1), T. SHIMADA2), N. INOMATA3) and M. OKAMOTO4) In the tissue culture of higher plants, chromosome constitution of callus cells varies in many species and with cultured conditions (FOX 1963, TORREY 1967). In order to study variation of chromosome constitution, more specifically in order to know whether any chromosome increases or decreases at random or whether a particular chromosome does increase or decrease, telocentric chromosomes (SEARS 1954) are very useful materials, because it is easy to detect the loss or increase of the telocentric chromosomes. The materials used in the experiment were the following five lines: Chinese Spring, nulli-5B tetra-5D, ditelo-5AL, -5BL and -5D, respectively. Sterilized seeds were placed on agar slant in the test tube, each containing 10 ml of the medium. The medium used in this experiment was RM-64 basal medium (LINSMAIER and SKOOG 1965), to which 3.0 mg/l of 2, 4-D (2, 4-dichlorophenoxy acetic acid) was added. Medium was adjusted to pH 5.8 with IN-KOH and IN-HCl before autoclaving. Calluses which were induced on growing roots of germinating seeds were successively subcultured at intervals of two months on the medium mentioned above. After pretreatment in water at 0'C for 24 hours and fixation in Farmer's fluid, microscopical observation of chromosome numbers were made by Feulgen squash method. Growth rate and morphology of calluses were about the same in different lines. Chromosome numbers of callus cells from Chines Spring were almost 2n=42. Nulli-5B tetra-5D and ditelocentric lines produced callus tissues whose chromosome numbers varied greatly from those of Chinese Spring. Chromosome numbers of callus cells from nulli-5B tetra-5D varied from 24. to 86 with the mode at 40 (32%), the majority of the chromosome numbers ranging from 38 to 42 (82%). In the callus cells of ditelo-5AL, their chromosome numbers varied from 27 to 126 with the mode at 42, 52% being 2n= 42. In the callus cells of ditelo-5BL, their chromosome numbers varied from 28 to 84 with the mode at 42, 58% being 2n=42. In the callus cells of ditelo-5D, chromosome numbers varied from 35 to 84, 68% being 2n=42. The fate of the telocentric chromosomes used in the present experiment will be discussed in the separate papers. |
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1) Shiga Agricultural College, Shiga Pref. Japan (Received July 1, 1972) |