Inhibitory effect of streptomycin on rice tissue cultures and the selection of resistant callus clones

Summary Callus tissues were initiated from seed, radicle and anther cultures of rice (Oryza sativa L.) in order to study the effect of streptomycin on callus growth. Our results showed that the addition of 250 g/ml or more streptomycin to the culture medium caused a significant inhibition of callus proliferation. The degree of inhibition depended upon the genotype, the drug concentration and the tissue source of callus. Selection of resistant cell lines began with seed and immature embryo cultures grown on various levels of streptomycin. The fastest growing sectors of callus were subcultured for additional selection. In this way, a total of 11 comparatively vigorous callus clones were isolated after 7 or 12 subcultures. Some of these clones exhibited a significant increase of resistance index when compared with unselected starting material. After 5 or 6 selection cycles, 79 plantlets were regenerated from resistant callus, but none grew to maturity because all were white (albino).