The unicellular alga Chlamydomonas reinhardtii has emerged as a powerful model system for studying chloroplast function, biogenesis and regulation for several reasons [1]. First, its photosynthetic function is dispensable, provided a source of reduced carbon such as acetate is present in the growth medium. It is thus easy to isolate, maintain and study mutants deficient in photosynthetic activity either in the dark (heterotrophic conditions) or in the light(mixotrophic conditions). Second, this alga is able to synthesize chlorophyll in a light-independent manner and can thus accumulate a fully functional photosynthetic apparatus when grown in the dark. This feature is particularly important as mutants deficient in photosynthesis are often light-sensitive and difficult to study in land plants. Third, transformation of this alga is possible for the nuclear, chloroplast and mitochondrial compartments. Finally, the nuclear, chloroplast and mitochondrial genomes have been sequenced and can easily be screened for the presence of specific genes [2–4].