New insights into the interaction network of plant sugar transporters

Plant sucrose transporters of the SUT and SWEET family are essential for phloem loading and unloading in higher plants. Members of both families are able to form homo- and hetero-oligomers, thereby changing their subcellular localization and functionality. Not only oligomerization, but also interaction with other proteinaceous interaction partners might affect the subcellular localization and thereby the functionality of plant sucrose and glucose transporters. Identification of individual interactomes of different sucrose or glucose transporters helped to assign different functions to each of the transporters since the population of protein-protein interaction partners varies considerably. Nevertheless, several common interaction partners could be identified for SUT1, SUT2, and SUT4 from Solanaceae, suggesting common regulatory mechanisms, although individual physiological functions are fulfilled. This review will focus on recent advances in the field of sugar transporter dynamics within and between cells, their targeting, and their functional regulation by direct physical contact with other proteins. Elucidation of the individual interactomes of sugar transporters of the SUT or SWEET family will help to understand their regulatory network and impact on the whole plant physiology, thereby opening up new strategies for crop plant adaptation to appropriate environmental conditions or climate change.