Starch granules come in all different shapes and sizes depending on botanical origin.
There is also substantial variation in the ratio of amylopectin and amylose in starch.
However, many questions about starch granule assembly and morphogenesis remain unanswered:
- How do the starch polymers assemble to form the semi-crystalline starch granule – is it self-assembly, or do specific proteins catalyse the process?
- How is granule growth directed to form different shapes – such as spheres, discs, or ovoids?
- What are the key determinants of granule size?
- What determines how much amylose is made into the granule, relative to the amount of amylopectin?
We have been investigating natural variation in starch granule shape, size and composition in order to identify key genetic differences that underpin the diversity.
Figure 1: We have also recently revealed the important role of the amyloplast (the plastid in which starch is made) in determining the shape of starch granules in wheat. This is described in Esch et al. (2023), which was featured on the cover of New Phytologist (https://doi.org/10.1111/nph.19118)