Abstract
Immature soybean seeds accumulate starch as a transient reserve material that declines later in seed development. Phosphorylase activity in cotyledons rapidly increased 40-50 days after flowering (DAF) corresponding to the starch breakdown. Decomposition of starch granules was intracellularly compartmented to arm loplasts which were associated with rough endoplasmic reticulum. Simultaneously with the phosphorylase activation, phytase activity appeared and increased till 45 DAF, and transitory decline of phytic acid was observed at the maximum of phytase activity. These results suggest that phosphorolysis may be involved in starch breakdown, and that phytic acid is mobilized in developing soybean seeds.
