Induction of DNA synthesis and callus formation from tuber tissue of Jerusalem artichoke by 2,4-dichlorophenoxyacetic acid

摘要

Cellus induction was observed from Jerusalem artichoke tuber tissue on a synthetic medium containing 2,4-D at 10−6, 10−5(optimum conc.) and 10−4M. The first DNA synthesis (thymidine incorporation) was observed only at 2,4-D concentrations of 10−5to 10−4M. In 10−5M2,4-D treated tissue, DNA synthesis increased after a 20 hr lag and reached a maximum at 36 hr, after which it decreased. Actinomycin D and 8-aza-guanine; inhibitors of RNA synthesis, inhibited DNA synthesis completely. 2,4-D caused the characteristic changes in RNA and protein syntheses. In comparison with the control, RNA and protein syntheses were first repressed then induced before the peak of DNA synthesis. Treatment with cycloheximide (10−4M) for one hour before inoculation inhibited protein synthesis completely for 12 hr; consequently DNA synthesis was also delayed. The results suggest that RNA and protein syntheses needed for callus induction are regulated by 2,4-D in the first