Substrate specificity and functional conservation of SWEET10 transporter in pineapple

Summary SWEET transporters are a unique class of sugar transporters that play vital roles in various developmental and physiological processes in plants. While the functions of SWEETs have been well established in model plants such as Arabidopsis , their functions in economically important fruit crops like pineapple have not been well studied. This study investigated the substrate specificity of pineapple SWEETs by comparing the protein sequences of known glucose and sucrose transporters in Arabidopsis to those in pineapple. Genome-wide approach and 3D structure comparison showed that the Arabidopsis SWEET8 homolog in pineapple, AcSWEET10, shares similar sequences and protein properties responsible for glucose transport. To determine the functional conservation of AcSWEET10, its ability to complement glucose transport mutants in yeast, its expression in stamens, and its impact on the microspore phenotype and seed set in transgenic Arabidopsis were analyzed. AcSWEET10 was found to be functionally equivalent to AtSWEET8 and plays a critical role in regulating microspore formation through the regulation of CalS5. Manipulating SWEET transporter activity could have important implications for improving fruit crop yield and quality.