Wang et al. [3] also discussed applying plastid transformation for metabolic pathway engineering in plants, the production of biopharmaceuticals, and marker gene excision system and how plastid transformation can be applied to study RNA editing. Similarly, Hefferon [67] , considers plastid engineering as a valuable tool that gives enormous promise for the production of biopharmaceuticals and vaccines, because higher level of the protein expressed by the transgene inserted into the plastid genome can be achieved. Many vaccine antigens, which played a key role for the prevention of infectious diseases, and biopharmaceutical proteins, have been expressed at high levels via the chloroplast genome [108] and they proved to be functional using in vitro assays in cell cultures. [109] stated that production of therapeutic proteins in plastids eliminates the expensive fermentation technology, and that the oral delivery of plastid-derived therapeutic proteins eliminates cold storage, cold transportation, expensive purification steps, and delivery via sterile needles, and hence decrease their cost. The main goal for applications of plastid transformation by the biotech industry is molecular pharming, and food production is considered as only a secondary target [80] .