Since plastids are transferred mostly through the "maternal inheritance" as identical copies, and hence a female plant transfers identical copies to all the seeds it produces without changes from one generation to the next, an important promise for applying plastid transformation for industry is the stable passing on to the next generation of the foreign DNA [80] . Therefore, the plastid genome has also been utilized for metabolic pathway engineering and in the field of molecular farming (the production of drugs and chemicals through engineered crops) [27, 68] for the expression and production of biomaterials and biopharmaceuticals in plants, human therapeutic proteins, and vaccines for use in humans or animals (reviewed in [26, 27, 50] . Singh et al. [26] believe that for such applications, plastid transformation technology offers solutions to the ecological and technical problems associated with conventional transgenic technologies such as outcrossing and transgene silencing.