Source metabolism dominates the control of source to sink carbon flux in tuberizing potato plants throughout the diurnal cycle and under a range of environmental conditions

The aim of this work was to investigate the effect of environmental conditions on the control of source to sink carbon flux in potato during tuberization. Top down metabolic control analysis was used to quantitatively determine the extent to which source and sink reactions control the flux from CO₂ to the tuber. Under all conditions investigated (beginning of the dark period, low nitrogen availability, variation in temperature) source metabolism accounts for at least 80% of the control. In plants grown with limiting nitrogen, or when measurements were made at low temperature the extent to which source metabolism controls flux increased to 90%.