ABSTRACT
The transfer ribonucleic acid (tRNA) population of animal and fungal mitochondria is usually different from that of the nucleus. The evolutionary pathway of plant mitochondria (mt) has been different from that of animal and fungal mitochondria: on the one hand plant mt genomes have inserted "promiscuous" cp DNA sequences containing tRNA genes and, on the other hand, plant mitochondria import tRNAs from the cytosol. The chapter shows that the potato mt genome contains at least 15 "native" and 5 "chloroplast-like" tRNA genes and that 11 potato mt tRNAs are coded for by the nuclear (nu) genome and imported from the cytosol. Import of nu-encoded tRNAs must occur in protozoan mitochondria, as Tetrahymena and Paramecium mt genomes contain only eight and three tRNA genes, respectively. The folded structures of most metazoan mt tRNAs resemble those of prokaryotic tRNAs and eukaryotic nu-encoded tRNAs. The complete set of tRNA species of Mycoplasma capricolum, a derivative of Gram-positive eubacteria, has been sequenced.
