In spite of this huge success in applying plastid engineering for molecular pharming, Ho & Cummins [73] referred to several risks of plastid engineering in producing GM pharmaceuticals that are associated with its advantages. For more details on the use of plastid engineering for biotechnology applications, see review by Verma & Daniell [5] . Other valuable reviews are available on (a) generation of plants with transgenic plastids, summary of our current understanding of the transformation process and highlights on selected applications of transplastomic technologies in basic and applied research [124] , (b) Progress in expressing proteins that are biomedically relevant, in engineering metabolic pathways, and in manipulating photosynthesis and agronomic traits and the problems of implementing the technology in crops [125] , (c) plastid transformation in higher plants [56] , (d) the characteristics, applications of chloroplast genetic engineering and its promising prospects, [126] , (e) Engineering the chloroplast genome [127] (f) exciting developments in this field and offers directions for further research and development, [128] (g) the expression of resistance traits, the production of biopharmaceuticals and metabolic pathway engineering in plants [27] , (h) chloroplasts as bioreactors, and whether we can replace plants with plants [129] , (i) how plastid transformation played an important role in understanding the RNA editing [3] and (j) comparison of opportunities and challenges between nuclear and plastid genetic engineering of plants [130] .