47

    Trisomics have been reported in the regenerates of anther culture in rice by a few investigators (Oono 1975; Chu et al. 1985). However, there is no report on morphological identification of such trisomics. In our experiment for producing aneuhaploids and tetrasomics in rice by means of anther culture of trisomics, we have also obtained a number of other aneuploids, such as trisomics and monosomics, other than the expected aneuhaploids and tetrasomics (Wang and Iwata 1991). We report here the results of morphological identification of these trisomics.
    Sixty-seven trisomics were detected in 2,606 regenerates derived from anther culture of eleven types of trisomics in the japonica variety "Nipponbare" (Table 1). Chromosome number of some trisomics was confirmed cytologically to be 25. Morphological identification of these trisomics was done using the mature plants, according to the method of lwata and Omura (1984). The resluts are shown in Table 1. The sixty-seven trisomics were divided into eleven groups. Among them, Fifty-five trisomics were found to be identical to their parent trisomics from which they were derived (Table 1 ). These trisomics obviously originated from the calli of somatic cells of anthers of the trisomics. The other twelve trisomics were grouped into six types: one Triplo 4 plant in the regenerates from Triplo 12; three Triplo 5 plants in the regenerates from Triplo 1 and 8: two Triplo 6 plants in the regenerates from Triplo 11 and 12; two Triplo 8 plants in the regenerates from Triplo 7 and 10; two Triplo 10 plants in the regenerates from Triplo 1 and 2; and two Triplo 12 plants in the regenerates from Triplo 2 and 5 (Table 1 ). These trisomics, differing from their parent trisomics, should be from the somaclonal variations induced during the culture. The frequency (0.46%: 12/2,606) of trisomic induction observed in this experiment was much lower than that reported by Chu et al. (1985)(5.4-6.7%). This is probably because of the short period of culture in the present experiment (about one month). We designed the experiment with the aim to reduce the somaclonal variation during the culture. A higher frequency of aneuploids including trisomics could be expected from the generates of anther culture if the incubation period were increased.
    In this study, we have detected six types of rice trisomics. Triple 4,5,6,8, 10, and 12, which should be from the somaclonal variation, induced during the anther culture. Our results provide more conclusive evidence for the method to get trisomics by means of anther culture in rice.

Table 1. Morphological identification of trisomics detected in the regenerates
from anther culture of trisomic plants in rice

Chu, Q., Z. Zhang and Y. Gao, 1985. Cytogenetical analysis on aneuploids obtained from pollenclones of rice
        (Oryza sativa L.). Theor. Appl. Genet. 71: 506-512.
Iwata, N. and T. Omura, 1984. Studies on the trisomics in rice plants (Oryza sativa L..). VI. An accomplishment
        of trisomic series in japonica rice plants. Jpn. J. Genet. 59: 199-204.
Oono, K., 1975. Production of haploid plants of rice (Oryza sativa L.) by anther culture and their use for
        breeding. Bull. Natl. Inst. Agric. Sci. Ser. D 26: 139-222. (in Japanese with English summary)
Wang, Z. X. and N. Iwata, 1991. Production of n+l plants and tetrasomics by means of anther culture of
        trisomic plants in rice (Oryza sativa L.). Theor. Appl. Genet. 83: 12-16.

Triple anther cultured	No. of regenerated � plants	No. of Triple plants detected										Total
Triple anther cultured	No. of regenerated � plants	1 2	4	5	6	7	8	9	10	11	12	Total
1	204	1		2					1			4
2	477	2							1		1	4
4	313		1									1
5	176			27							1	28
6	138				14							14
7	95					2	1					3
8	215			1			1					2
9	84							1				1
10	424						1		2			3
11	228				1					3		4
12	252		1		1						1	3
Total	2,606	1	2	30	16	2	3	1	4	3	3	67