Salt effects on total and gene-specific in vitro transcriptional activity of isolated plant nuclei.

Nuclei from cell suspension cultures of parsley (Petroselinum crispum L.) were isolated and the effects of salt concentrations on the in vitro transcriptional activity determined. Increasing concentrations of monovalent and divalent cations stimulated α-amanitin sensitive transcriptional activity, whereas α-amanitin insensitive transcriptional activity was not affected. The relative rates of in vitro synthesis of rRNA and four different mRNAs at selected salt concentrations were greatest when the transcription assays were carried out at the lowest salt concentrations tested. Hence, optimal conditions for total RNA synthesis (high salt concentrations) were not necessarily optimal for the run-off transcription of particular genes (low salt concentrations) in isolated nuclei.