beginning of the pathway results in a phenotype that is
much less severe. This is the case in sex4 plants missing the
phosphoglucan phosphatase; these plants accumulate 50%
of the starch of sex1 plants and the diel synthesis and
degradation of starch is still observed (Zeeman et al., 1998).
These sex4 plants have a phenotype almost indistinguishable
from that of the wild type (see Supplementary Movie
S1). The phenotype of other starch-accumulating mutants
such as mex1, which lacks the maltose transporter in the
plastid inner envelope, and dpe2, which lacks the cytosolic