The contribution of plastidial phosphoglucomutase to the control of starchsynthesis within the potato tuber

The aim of this work was to evaluate the extent to which plastidial phospho glucomutase (PGM) activity controls starch synthesis within potato (Solanum tuberosum L. cv. Desire) tubers. The reduction in the activity of plastidi al PGM led to both a correlative reduction in starch accumulation and an in creased sucrose accumulation. The control coefficient of plastidial PGM on the accumulation of starch was estimated to approximate 0.24. The fluxes of carbohydrate metabolism were measured by investigating the metabolism of [ U-C-14]glucose in tuber discs from wild-type and transgenic plants. In tube r discs the control coefficient of plastidial PGM over starch synthesis was estimated as 0.36, indicating that this enzyme exerts considerable control over starch synthesis within the potato tuber.