Many crops—including potatoes, bananas, and breadfruit—rely on starch as a long‑term energy reserve. This carbohydrate is stored in dedicated organelles called amyloplasts.
During photosynthesis, plants synthesize glucose. Because free glucose is hard to store, it is either converted into sucrose for transport or polymerised into starch. Polymerisation links glucose units into long chains that can be safely stored inside cells.
Amyloplasts are non‑pigmented plastids that specialize in starch biosynthesis. They take glucose, assemble it into starch granules, and relocate these granules to the stroma—the spacious, colourless matrix within the organelle.
The stroma provides a supportive environment for starch granules. In storage tissues such as tubers and rhizomes, it acts as a reservoir, allowing the plant to mobilise glucose when energy is needed.
When the plant requires energy, the starch is enzymatically broken down back into glucose, fueling growth, metabolism, and reproduction.
