Abstract Sugars Will Eventually be Exported Transporters (SWEETs) are the most recently discovered family of plant sugar transporters. Functioning as uniporters and thus facilitating the diffusion of sugars across cell membranes, SWEETs play an important role in various physiological processes such as abiotic stress adaptation. AtSWEET17, a vacuolar fructose facilitator, was shown to be involved in the modulation of the root system during drought. Moreover, overexpression of a homolog from apple results in increased drought tolerance of tomato plants. Therefore, SWEET17 appears to be essential for the plant’s drought response. Nevertheless, the role and function of SWEET17 in aboveground tissues under drought stress to date remains enigmatic. By combining gene expression analysis with analysis of the sugar profile of various aboveground tissues, we uncovered a putative role of SWEET17 in the carbohydrate supply, and thus cauline branch emergence and growth, particularly during periods of carbon limitation as occurs under drought stress. SWEET17 thereby being of critical importance for maintaining efficient reproduction under drought stress. Highlight The fructose transporter SWEET17 supports shoot branching by increasing mobilization of carbohydrates from vacuoles to supply the newly forming inflorescence branch, thereby maintaining efficient reproduction under drought stress.

Carbohydrate distribution via SWEET17 is critical for Arabidopsis inflorescence branching under drought