The effect of 4-thiouridine (4SU) on metabolic activities of organelles other than plastids was investigated by examining growth parameters, cellular enzyme activities and metabolic behaviors of greening radish seedlings germinated and grown with 4SU. Seedling growth was not severely affected by 4SU culture. Mitochondrial, peroxisomal and microsomal marker enzymes and cytoplasmic enzyme activities were not generally changed in the 4SU-cultured radish cotyledons. The respiration rate of mitochondria isolated from 4SU-cultured cotyledons was also normal. Some soluble enzymes of the isolated plastids had normal or even higher activities. However, chloroplastic pigments and ribulose bisphosphate carboxylase activity decreased with increasing concentration of 4SU in the culture medium. We concluded that the inhibitory effect of 4SU was limited to chloroplast development.
展开▼
