Microalgae are able to efficiently convert sunlight, water, and CO2 into a variety of products suitable for renewable energy applications, including H2, carbohydrates, and lipids . The unicellular green alga Chlamydomonas reinhardtii has emerged as a model organism for studying algal physiology, photosynthesis, metabolism, nutrient stress, and the synthesis of bioenergy carriers . During acclimation to nitrogen deprivation, C. reinhardtii cells accumulate significant quantities of starch and form lipid bodies . Despite the significance of these products in algal physiology and in biofuels applications, the metabolic, enzymatic, and regulatory mechanisms controlling the partitioning of metabolites into these distinct carbon stores in algae are poorly understood. Several C. reinhardtii starch mutants with various phenotypic changes in starch content and structure have been isolated (2,–4). Two of these, the sta6 and sta7 mutants, contain single-gene disruptions that result in “starchless” phenotypes with severely attenuated levels of starch granule accumulation