Figure 6.

The pathway of starch biosynthesis in leaves.

Carbon assimilated via the Calvin cycle is partitioned with a fraction exported to the cytosol for sucrose synthesis and a fraction retained in the chloroplast for starch synthesis. Redox and allosteric regulation of the enzyme AGPase controls the flux of carbon into starch. Mutants deficient in plastidial PGI, PGM1 and AGPase have major reductions in starch contents, although small amounts remain, suggesting an alternative minor route (see text). Image reprinted from Zeeman et al. (2007) with permission from Portland Press.