ABSTRACT
Leaf starch degradation is initiated by phosphorylation of amylopectin via glucan, water dikinases (GWD and PWD). Dephosphorylation of the phosphoglucans by glucan phosphatases (SEX4 and LSF2) presumably occurs concurrently. Debranching of the starch polymers at the granule surface is mainly via isoamylase 3 (ISA3), and linear glucans are metabolized via β-amylase (BAM) to yield maltose as the main product. Maltose is exported from the chloroplast to the cytosol where it is converted to sucrose.
