Fig. 1

Dynamic amyloplast morphogenesis during pollen germination. Lily pollen grains underwent germination in a culture medium with either 290 mM sucrose (A-D) or 290 mM pentaerythritol (E-G) for varying time intervals: 0 min (A), 30 min (B and E), 60 min (C and F), and 90 min (D and G). The samples were rigorously fixed and subsequently embedded in Spurr’s resin to facilitate high-resolution ultrastructural analysis. In the initial stage, mature lily pollen grains exhibited minimal to no presence of starch granules or amyloplasts (A). However, as the process of pollen germination advanced, starch granules commenced accumulating within amyloplasts (B-D). Simultaneously, the quantity of starch granules increased proportionally with the expansion of amyloplasts. Notably, this pattern of amyloplast development persisted even when pollen grains were germinated without sucrose (E-G). In panels (B-D), solid arrows denote double-membrane structures enveloping differentiating amyloplasts, whereas open arrows indicate those enclosing lipid bodies. Key cellular components are appropriately labeled: a (amyloplast), g (Golgi apparatus), l (lipid body), m (mitochondria), v (vacuole). The Scale bars represent 1 μm, ensuring precise measurement in the ultrastructural analysis