烟草愈伤组织继代培养与分化期间核酸代谢的比较研究

A comparative study on the metabolism of nucleic acids during the subculture and differentiation of tobacco callus]

Changes in the contents of DNA and RNA, RNA species, the synthesis rates of DNA and RNA, and the activity of DNase and RNase were investigated in the callus of tobacco (Nicotiana tabacum L. cv. Willow Leaf) during subculture and differentiation. The contents of DNA and RNA were higher in differentiating callus than that in subcultured callus. After day 12, the contents of DNA and RNA in differentiating callus rose continuously while the contents of DNA and RNA in subcultured callus remained constant. Changes in RNA species and its relationship to total RNA level were also analyzed. At the stage of shoot primordium formation in differentiating callus, the activity of RNase increased markedly and the synthesis rate of RNA increased continuously; while the RNase activity and the synthesis rate of RNA in subcultured callus were much lower during the same period. During the period of shoot growth, the synthesis rate of DNA in differentiating callus was elevated compared to that in subcultured callus. The results above suggested that the metabolism of nucleic acids in differentiating callus was more active than that in subcultured callus.