RNA from callus cultures and leaves of Nicotiana tabacum

MAK column chromatography has been used to analyse RNA from normal and crown gall callus cultures and leaves of Nicotiana tabacum. To determine the elution behaviour of well-defined DNA-like RNAs with different GC content, complementary RNAs (c-RNA) synthesized on Agrobacterium tumefaciens DNA and crown gall DNA were used. The elution profile of the RNA from all three tissues followed a similar pattern. By salt gradient elution the RNA in the tRNA region showed a remarkably high CMP content which was significantly higher for the normal tissues than for crown gall tissue. RNA from the callus cultures contained more DNA-like RNA (D-RNA) with a higher turnover rate than RNA from leaves. Because of its relatively low poly A content, measured as RNase A + T₁ resistance, as well as its high turnover rate, the salt-eluted D-RNA is thought to be heterogeneous nuclear RNA (Hn-RNA) and not mRNA. RNA molecules that might represent the mRNA population, having intramolecular poly A tracts, were subsequently eluted by a salt gradient, a low salt buffer and with the chaotropic agent guanidine thiocyanate, which removed tenaciously bound (TB-RNA) in two fractions, α and β. Crown gall RNA showed both a different labelling behaviour and a higher poly A content in the α and β fractions compared to the normal tissues. c-RNAs may be eluted at different salt concentrations because of their different GC content. They give rise to a considerable fraction of TB-RNA which in the presence of tobacco leaf RNA was split into fractions similar to α and β. No fraction was found amongst these RNAs which did have intramolecular poly A tracts.