Unravelling novel mechanisms of starch granule biogenesis in potato

Starch is a unique biopolymer in that it forms semi-crystalline starch granules. The aim of this work is to investigate mechanisms of starch granule formation in potato tubers. Potato starch is widely consumed as a dietary carbohydrate in many parts of the world and consists of distinctive large ellipsoid starch granules. However, little is known about how these granules are formed during tuber development, and the mechanisms underpinning their unique size and shape. In this project, we will explore starch granule initiation and morphogenesis in developing potato tubers. Using a series of gene-edited potato mutants, we will study how the unique complement of granule initiation proteins expressed in the tuber influences the number and size of starch granules. We will also explore the process of granule morphogenesis, based on exciting preliminary data that this could be an active process requiring a specific initiation protein homolog. We will examine the links between new granule formation and new amyloplast formation during potato tuber development, and study the structure of amyloplasts in unprecedented detail using 3D electron microscopy. Since starch granule morphology is thought to be a major determinant of starch quality in foods, we will also use the unique material generated within this project to test the impact of granule size and shape on starch functionality, digestibility and potato food quality, together with the industrial partner, Simplot. This work will lead to exciting fundamental mechanisms of granule biogenesis in an important crop, which will have major implications on potato quality.