ABSTRACT
One of the most promising plant expression systems for protein production stems from the engineering of chloroplasts via plastid transformation. Chloroplast engineering involves the introduction of thousands of copies of a foreign gene of interest per cell, and, as a consequence, the production of the foreign protein may reach levels as great as 46% of total soluble protein (TSP) (Daniell, 1999; Daniell et al., 2002; Daniell and Dhingra, 2002). This feature gives chloroplast engineering enormous promise for the production of vaccine proteins and biopharmaceuticals. In addition, plastid transformation is a more environmentally friendly approach to plant engineering because it both minimizes outcrossing of transgenes to weedy relatives and eliminates the possibility of transferring potentially toxic transgenic pollen to nontarget insects, as will be discussed in more depth in the following text.
