NUCLEAR AND CHLOROPLAST TRANSFORMATION IN CHLAMYDOMONAS-REINHARDTII -STRATEGIES FOR GENETIC MANIPULATION AND GENE-EXPRESSION

Transformation of the nuclear, chloroplast, and mitochondrial genomes can now be accomplished in Chlamydomonas reinhardtii. Many biosyntheti c pathways are carried out in the chloroplast, and efforts to manipula te these pathways will require that gene products be directed to this compartment. Chloroplast proteins are encoded in either the chloroplas t or nuclear genome. In the latter case they are synthesized in the cy toplasm and imported post-translationally into the chloroplast. Thus, strategies for expressing foreign genes or overexpressing endogenous g enes whose products reside in the chloroplast could involve either gen ome. This paper reviews the present status of transformation methodolo gy for the nuclear and chloroplast genomes in Chlamydomonas. Considera tions for expressing gene products in the chloroplast are discussed. E xperimental evidence for homologous recombination during transformatio n of the nuclear genome is presented.