Differential import of nuclear-encoded tRNAGly isoacceptors into Solanum tuberosum mitochondria

In potato (Solanum tuberosum) mitochondria, about two-thirds of the tRNAs are encoded by the mitochondrial genome and one-third is imported from the cytosol. In the case of tRNA(Gly) isoacceptors, a mitochondrial-encoded tRNA((GCC))(Gly) was found in potato mitochondria, but this is likely to be insufficient to decode the four GGN glycine codons. In this work, we identified a cytosolic tRNA((UCC))(Gly), which was found to be present in S.tuberosum mitochondria. The cytosolic tRNA((CCC))(Gly) was also present in mitochondria, but to a lesser extent. By contrast, the cytosolic tRNA((GCC))(Gly) could not be detected in mitochondria. This selective Import of tRNA(Gly) isoacceptors into S.tuberosum mitochondria raises further questions about the mechanism underlying the specificity of the import process.