Schematic model of the cellular route of sugar transport from the endosperm to the sieve element in germinating wheat seeds, highlighting the potential location of sugar transporters and symplasmic transport. TaSUT1 is represented by a larger circle, Glc transporters by a rectangle, and a putative Suc effluxer by a smaller circle. SPS, Suc phosphate synthase; hexose-P, hexose phosphate.