The gene encoding Arabidopsis thaliana mitochondrial ribosomal protein S13 is a recent duplication of the gene encoding plastid S13

A gene encoding mitochondrial S13 is generally present in the mitochondrial genome of higher plants. but is lacking from the Arabidopsis thaliana mitochondrial genome. Previous research has failed to identify a nuclear gene capable of encoding a mitochondrial S13 protein or the protein itself. Doubts have even been raised as to whether a mitochondrial S13 exists in Arabidopsis. Here, we show that the nuclear gone encoding the plastid S 13 has been partially duplicated in A. thaliana. such that the copy has lost the exon encoding the plastic. transit peptide and acquired a sequence capable of encoding a mitochondrial targeting sequence. The two S13 sequences were fused to green fluorescent protein and shown to be targeted to plastids and mitochondria respectively.