Synthesis of 5S rRNA and putative precursor tRNAs in nuclei isolated from wheat embryos.

Nuclei isolated from wheat embryos synthesize 4.5S precursor tRNAs and 5S rRNA in vitro. The precursor tRNAs can be processed to 4S tRNAs. Transcription of the tRNA and 5S rRNA genes is carried out by endogenous RNA polymerase III, and addition of exogenous wheat RNA polymerase III results in increased transcription on these genes. A number of experimental results suggest that proper initiation and accurate transcription of the tRNA and 5S rRNA genes occurs with isolated wheat nuclei.