Patterns of nucleic acids synthesis in normal and crown gall tumor tissue cultures of tobacco

Abstract

The bacteria-free crown gall tumor tissue cultures of tobacco were 40–90% higher in nucleic acid content and up to 10–15 times higher in the capacity to incorporate 32P into RNA than the normal tissue cultures. Examination of the 32P sedimentation profile of rapidly labeled nucleic acids from normal and tumor tissue cultures (12–42 days old) suggested some differences between the normal tissue and the tumor tissue, although the profiles also changed with the culture age. Since the 32P nucleotide composition (AMP + UMP = 54–58%) of total RNA and of different RNA fractions, obtained by density gradient centhfugation, was similar to DNA (A + T = 61%) rather than ribosomal RNA (AMP + UMP = 44%), the RNA labeled with 32P was considered to represent principally mRNA. Both the absorbance and the 32P nucleotide compositions of total RNA from normal tissue were similar to those from tumor tissue, and, except for fraction “C,” consistent differences in the 32P nucleotide compositions of different RNA fractions from normal and tumor tissue were not very apparent.