Mediates both low-affinity uptake and efflux of sugar across the plasma membrane. Required for pollen viability. Involved in the transport of copper, in cooperation with COPT1 and COPT2 (PubMed:16648463, PubMed:20852017, PubMed:21107422, PubMed:25988582). Confers sensitivity to bacterial blight mediated by X.oryzae pv. oryzae (Xoo) in its Xa13 allelic form (e.g. cv. IR24), probably by providing the sugar required for the pathogen growth, or by reducing copper contents in xylem. However, a recessive resistance can be associated with the xa13 allele (in which the promoter is mutated leading to reduced induction upon pathogen infection, e.g. cv. IRBB13), specifically toward Xoo Philippine race 6 and Indian race PXO8. Interacts with COPT1 and COPT2 (PubMed:20852017). Interacts with APX8 (PubMed:27185545). Mostly expressed in panicles and anthers. Also detected in leaves (leaf collar, leaf auricle, leaf ligule), roots, sheaths, culms and culm nodes. Accumulates to high levels in pollen grains, tapetal cells, and middle-layer cells of the anther wall. Also detected at high levels in connective tissue cells and the connective vascular element at the unicellular- to-bicellular pollen grain stages. At the tricellular pollen grain stage, confined to the cells of connective vascular elements. By the X.oryzae pv. oryzae (Xoo) transcription activator-like effector (TALe) protein pthXo1 and, possibly, AvrXa7. Reduced starch content in pollen and male sterility. Enhanced resistance against bacterial blight mediated by X.oryzae pv. oryzae (Xoo) strain PXO99(A). Belongs to the SWEET sugar transporter family.