Manufacturing pharmaceutical products in plant crops has been one of the promised benefits of plant genetic engineering for the past two decades. This practical application of biotechnology, also termed as “pharming,” “bio-pharming,” or “molecular farming,” has progressed from speculation to the testing phase in fields and greenhouses across the world.

   While short peptide chains containing less than 30 amino acids can be synthesized in the laboratory chemically, larger proteins are best produced by living cells. The DNA that encodes the instructions for producing the desired protein is inserted into cells, and as the cells grow they synthesize the protein, which is subsequently harvested and purified. Of course, plants have always been providing humans with useful molecules since centuries, but only during the past 20 years it has became possible to use plants for the production of specific heterologous....