Fig. 1. Somatic prometaphase chromosomes of plants with 2n=13 (left) and 2n= 26 (right) regenerated from trisomic type H. Arrows show the satellite chromosomes.
Faculty of Agriculture, Kyushu University, Hakozaki, Fukuoka, 812 Japan
In order to obtain X+1 plants of rice, we carried out anther culture of the trisomic plants of Japonica variety, Nippoiibare. In 1988, 19,700 anthers from six types of trisomics (Table 1; Iwata and Omura 1984) were cultured on N6 medium supplemented with 2 mg/l 2,4-D. A total of 3,204 calli were obtained with an average induction frequency of 15.4% (Table 1). The callus induction frequency varied among trisomic types from the lowest (3.9%) for type A to the highest (32.6%) for type D. Of the calli, 2,670 were transferred onto MS+ 1 mg/l IAA regeneration media and 483 green plants were obtained. The regeneration frequency varied from the lowest (6.5%) for type A to the highest (24.9%) for type C (Table 1).
Table 1. Frequency of callus production and plant regeneration
in anther culture of different trisomics
________________________________________________________________
Trisomic type Anthers Callus Callus Plants
plated induced transferred regenerated
________________________________________________________________
A (Pale) 1700 66(3.9%) 61 4 (6.5%)
B (Awned) 4000 353(8.8%) 307 69 (22.5%)
C(Small grain) 4000 469(11.7%) 422 105 (24.9%)
D (Erectoides) 4000 1303(32.6/5) 1168 197 (16.9%)
E (Spreading) 1000 42(4.2%) 38 8 (21.1%)
H(Large grain) 5000 791(15.8%) 674 100 (14.8%)
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Total 19700 3024(15.4%) 2670 483 (18.1%)
The regenerated plants were grown in pots under good management in
greenhouse. When they reached the 5-leaf stage, their morphological
features and root-tip chrornosomes were examined. A total of 131 plants
which were examined showed chromosome numbers ranging from 13 to 73
(Table 2). Plants with 2n= 13, called "disomic haploid", were detected in
four trisomics, e.g., A, B, C and H. Plants with 2n= 26 were found in
types B, C, D and H, which might have resulted from chromosome doubling in
cells with 2n= 13. A few other aneuploids including a monosomic and 2n =
73 plant were also obtained (Table 2).The plants with 2n = 13 and 2n = 26 regenerated from the same trisomic type were morphologically similar to each other, but those from different types showed different features. The prometaphase chromosomes of plants with 2n = 13 and 2n = 26 derived from trisomic type H are shown in Fig. 1. The extra chromosomes all had a satellite, which were the extra chromosome of the trisomic used as donor, corresponding to Nishimura's chromosome 1. These observations suggest that the
Table 2. Chromosome numbers of plants regenerated from trisomics
________________________________________________________________
Trisomic Numbers of plants with
type _______________________________________________ Total
2n=12 2n=13 2n=23 2n=24 2n=25 2n=26 2n=48 2n=73
________________________________________________________________
A 1 1
B 1 6 2 8 17
C 21 1 8 1 3 1 35
D 38 13 1 2 54
E 3 3
H 6 5 1 4 1 3 1 21
________________________________________________________________
Total 69 13 1 27 3 16 1 1 131
extra chromosomes of plants with 2n- 13 and 2n=26 do not come from random
chromosomal variations during culture, but are derived from pollen grains
with n = 13 of the trisomic plant. The present study shows that X + 1 plants
can be obtained from anther culture of trisomics in rice in the same manner
as were obtained in tobacco (Niizeki et al. 1984).
Fig. 1. Somatic prometaphase chromosomes of plants with 2n=13 (left) and 2n=
26 (right) regenerated from trisomic type H. Arrows show the satellite
chromosomes.
References
Iwata, N. and T. Omura, 1984. Studies on the trisomics in rice plants (Oryza sativa L.) VI. An accomplishment of a trisomic series in japonica rice plants. Jpn. J. Genet. 59: 199-204.
Niizeki, M., Hayashi, H. and K. Saito, 1984. Production of disomic haploids by anther culture of a series of trisomic plants in Nicotiana sylvestris. Jpn. J. Breed. 34: 1-8.