Twin-arginine translocation pathways have been well characterized in bacteria and chloroplasts. However, genes encoding for a TatC protein are found in almost all plant mitochondrial genomes. For the first time it could be demonstrated that this mitochondrial encoded TatC is a functional gene which is translated into a protein in the model plant Arabidopsis thaliana. An inner membrane localized TatB like subunit was also identified, which is nuclear encoded, and is essential for plant growth and development. Indicating that plants potentially require a Tat pathway for mitochondrial biogenesis.