Genome-Wide Identification, Plasma Membrane Localization, and Functional Validation of the SUT Gene Family in Yam (Dioscorea cayennensis subsp. rotundata)

Yam (<i>Dioscorea cayennensis subsp. rotundata</i>,hereafter referred to as <i>Dioscorea rotundata</i>) is a staple tropical tuber crop with notable nutritional and economic value. Its development and yield depend on efficient sucrose allocation from source tissues. Sucrose transporters (SUTs), a conserved family of membrane proteins, mediate sucrose loading, translocation, and unloading. Although well-studied in model plants and cereals, SUTs in yam remain largely uncharacterized. This study aims to identify and characterize the <i>SUT</i> gene family in yam and explore their roles in sucrose transport and tuber development. We conducted a genome-wide analysis of yam <i>SUT</i> genes, including gene structure, subcellular localization, and phylogeny. Molecular docking was used to predict sucrose-binding residues, and qRT-PCR assessed gene expression across tissues and tuber developmental stages. Eight <i>SUT</i> genes were identified and classified based on sequence similarity and domain structure. Docking analysis revealed key residues involved in sucrose binding and possible conformational shifts influencing transport. Expression profiling showed that most <i>SUT</i> genes, especially in the tuber apex, were progressively upregulated during development, suggesting roles in sucrose unloading and cell expansion. Additionally, functional validation of <i>DrSUT1</i> in Arabidopsis thaliana confirmed its involvement in sucrose transport, supporting its role in yam sucrose partitioning. Yam <i>SUT</i> genes, especially those highly expressed in sink tissues, are involved in sucrose partitioning and tuber development. These findings provide structural and functional insights into SUT-mediated sugar transport and lay a foundation for improving sucrose utilization and yield in yam and other tuber crops.