Callus formation of somatic hybrid of rice and soybean and characteristics of the hybrid callus

抄録

Induction of calli from rice (strain A-58) and soybean (cv. Harosoy) protoplast mixtures treated by polyethyleneglycol (PEG) was successful and hybrid calli were able to be identified and selected by the observation of a blackish purple pigment of fravonoids in the rice calli and a softness in the soybean calli. However, the blackish purple pigment of hybrid calli disappeared rapidly after one or two subcultures. The peroxidase and esterase isozyme band patterns of all hybrid calli after several subcultures were that of soybean callus. From these results, it can be supposed that rice chromosomes are rapidly eliminated, while soybean nuclear genome may be retained in the hybrid calli. During subcultures of the hybrid calli, yellow, green and white calli have been segregated. The soybean calli were usually yellow, but sometimes turned green. The rice calli were a blackish purple which was so unstable that whitish yellow calli were often obtained. When all these calli were transferred onto the medium containing 1-naphthaleneacetic acid (NAA) and kinetin, the whitish yellow calli of rice and the white calli segregated from the hybrids did not usually turn green. Nevertheless the segregated white calli occasionally produced green parts in a mosaic pattern during long term cultures. On the other hand, soybean calli, and yellow and green calli segregated from the hybrids became green or remained green. Analysis of Fraction I protein showed that the segregated green calli have soybean chloroplasts, while the white calli have both of rice and soybean chloroplasts. Therefore, it may be considered that the segregated green calli have mainly soybean nuclei and soybean chloroplasts, while the white calli have soybean nuclei, and rice and soybean chloroplasts in a mosaic pattern.