The most common method for plastid transformations is biolistics: Small gold or tungsten particles are coated with the plasmid vector and shot into young plant cells or plant embryos, penetrating multiple cell layers and into the plastid.[1] There will then be a homologous recombination event between the shot plasmid vector and the plastid's genome, hopefully resulting in a stable insertion of the gene cassette into the plastid.[8] Whilst the transformation efficiency is lower than in agrobacterial mediated transformation, which is also common in plant genetic engineering, particle bombardment is especially suitable for chloroplast transformation.