THE POTATO MITOCHONDRIAL INITIATOR METHIONINE TRANSFER-RNA GENE AND ITS FLANKING REGIONS - AN ILLUSTRATION OF THE DIVERSITY OF MITOCHONDRIAL GENOME REARRANGEMENTS AMONG PLANT-SPECIES

The initiator methionine transfer RNA (tRNAf(Met)) gene was identified on a 347 bp Eco RI-Hind III DNA fragment of the potato mitochondrial (mt) genome. The sequence of this gene shows 1 to 7 nucleotide differe nces with the other plant mt tRNAsf(Met) or tRNAf(Met) genes studied s o far. Whereas the tRNAf(Met) gene is present as a single copy in the potato mt genome, a tRNA 'pseudogene' corresponding to 60% of a comple te tRNA (from the 5' end to the variable region) and located at 105 nu cleotides upstream of the tRNAf(Met) gene on the opposite strand was s hown to be repeated at least three times. Furthermore, the physical en vironment of the tRNAf(Met) gene in the mt genome is very different am ong plants, which suggests that the tRNAf(Met) gene region has often b een implicated in recombination events of plant mt genomes leading to important rearrangements in gene order.