Variability in Complementarity for Chloroplastic and Cytoplasmic Ribosomal Ribonucleic Acid among Plant Nuclear Deoxyribonucleic Acids.

The nuclear DNAs from a number of angiosperm species were tested for hybridization to the RNAs contained in 70 S (chloroplastic) and 80 S (cytoplasmic) ribosomes. All of the DNAs contained regions complementary to RNAs from chloroplastic as well as cytoplasmic ribosomes. DNAs from closely related plants varied widely in their proportion of coding for these RNAs. About 0.15% of the DNAs from a number of different species of Nicotiana were found to be complementary to the RNAs of each kind of ribosome; however, DNAs from some other members of this genus had more than three times this proportion of coding for ribosomal RNAs. These and other data suggest that hybridization percentage for ribosomal RNA is not a familial or generic characteristic.DNAs with high amounts of coding for ribosomal RNAs have thus far been found to contain satellite DNAs of base composition more like ribosomal RNA than the main DNA component. The satellite DNA from pumpkin has been isolated and shown to contain cistrons for both chloroplastic and cytoplasmic ribosomal RNAs.