The heterotrophic dinoflagellate Crypthecodinium cohnii defines a model genetic system to investigate cytoplasmic starch synthesis.

The nature of the cytoplasmic pathway of starch biosynthesis was investigated in the model heterotrophic dinoflagellate Crypthecodinium cohnii. The storage polysaccharide granules were shown to be composed of both amylose and amylopectin fractions with a chain length distribution and crystalline organization very similar to those of green algae and land plant starch. Preliminary characterization of the starch pathway demonstrated that C.