Plants with Transgenic Plastids

Plant genetic engineering will likely contribute to the required continued increase in agricultural productivity during the coming decades. Moreover, plants can potentially provide inexpensive production platforms for pharmaceuticals and nutraceuticals. With the advent of technologies to alter the genetic information inside plastids (chloroplasts), a new attractive target for genetic engineering has become available to biotechnologists. There are considerable attractions of the plastid genome as a target for the expression of foreign genes. These include (i) the plastids’ potential for high-level foreign protein expression, (ii) the possibility of transgene stacking through expression of multiple genes from operons, and (iii) the absence of position effects and epigenetic gene silencing mechanisms (Bock, 2001; Khan and Bock, 2004). From the biosafety perspective, the major attraction is the exclusively or predominantly maternal inheritance of the plastid genome in most crop plants, greatly reducing the risk of uncontrolled pollen spread of transgenes and thus allaying concerns over environmental consequences of GM crop cultivation.