ABSTRACT
31Chloroplasts are subcellular organelles (plastids) of plant cells generally considered to be derived from the prokaryotes, that is, probably from endosymbiotic cyanobacterium that was taken up by eukaryotic cells in symbiotic associations very early during the course of evolution. Chloroplasts have their own genome, and it resembles that of bacteria not that of the nuclear genome. There are no histones associated with the DNA. Chloroplasts have their own protein-synthesizing machinery, and it more closely resembles that of bacteria than that found in the cytoplasm of eukaryotes. Till date, genetic engineering has been experienced mostly in the nuclear genome. However, inserting transgene(s) into the nuclear genome has led to an increasing public concern of the possibility of escape of the transgene through pollen to wild or weedy relatives of the transgenic crops. Scientists suggested that since plastids are compared with prokaryotes, they can take up DNA as in bacterial transformation using naked DNA. Therefore, during the past few years, researchers have begun to evaluate application of plastid transformation in plant biotechnology as a viable alternative to conventional technologies for transformation of the nuclear DNA.
