ABSTRACT
Plants possess three major genomes, carried in nucleus, chloroplast and mitochondrion. This chapter discusses transformations of organellar genomes of chloroplast and mitochondrion. It provides a discussion on the selectable markers for chloroplast transformation. Chloroplast transformation was considered at one stage to be an impossible thing because of double membrane of the organelles acting as a physical barrier. Also there are no viruses or bacteria which could infect chloroplasts and act as vector for gene transfer. However, lately some successes have been achieved in chloroplast transformation. Some of the methods used for gene transfer into plant nuclei can also bring about transformation of chloroplasts. The chapter also describes these chloroplast transformation methods. Stable chloroplast transformation depends on the integration of the foreign DNA into the chloroplast genome by homologous recombination, therefore the foreign gene that is being introduced must be flanked by sequences homologous to the chloroplast genome.
