Our goal is to make the mitochondrial genome (mtDNA) into a platform for synthetic biology by developing mtDNA transgenesis in plants. This may contribute to biotechnology and agriculture in several ways. Because mtDNA is present in many copies per cell, high-level expression of mtDNA-encoded transgenes may be possible. The mitochondrial matrix, wherein mtDNA resides, provides an isolated compartment in which novel products can be synthesized and metabolic engineering carried out. mtDNA gene regulation uses prokaryotic-type machinery. Therefore, it is possible that, as with the chloroplast, transgene expression and translation can be regulated using prokaryotic components, which are well characterized. This, and the operon arrangement of many genes in plant mtDNA, may allow for orthogonal control and stacking of traits and pathways in mtDNA. Finally, mitochondria can migrate through a graft, from one plant to another. This opens up the possibility of moving transgenes and engineered pathways from one plant variety or species to another independent of mating.