Mechanisms of phloem unloading: shaped by cellular pathways, their conductances and sink function.

•Mechanisms of phloem unloading are set by the cellular pathway followed.•SWEET uniporters are key mediators of apoplasmic phloem unloading of sugars.•Symplasmic unloading by bulk flow is regulated by plasmodesmal conductances.•Aquaporin activities could constrain apoplasmic and symplasmic unloading rates.