# Genome-Wide Identification and Expression Profiling of Plasma Membrane-Localized SWEET Gene Family Associated with Sugar Transport During Yam Tuber Development

## TL;DR

This study identifies and characterizes SWEET genes in yam, revealing their role in sugar transport and tuber development.

## Contribution

The first genome-wide analysis of SWEET genes in yam, linking their function to sucrose transport and tuber growth.

## Key findings

- Nineteen SWEET genes were identified and predicted to localize to the plasma membrane in yam.
- DrSWEET6 and DrSWEET12 transport both hexose and sucrose, with high expression in tubers.
- SWEET gene expression increases during tuber development, supporting roles in sucrose unloading and biomass accumulation.

## Abstract

This study provides the first comprehensive genome-wide identification and characterization of the SWEET gene family in yam (Dioscorea rotundata), integrating structural bioinformatics, gene expression profiling, and functional validation to explore its roles in sucrose transport and tuber development. A total of 19 SWEET genes were identified and predicted to localize to the plasma membrane, and they showed high phylogenetic conservation with Arabidopsis thaliana, suggesting conserved functions in sugar distribution. Yeast substrate assays revealed that DrSWEET6 and DrSWEET12 are capable of transporting both hexose and sucrose across the plasma membrane, with their expression predominantly observed in the tuber, implicating their involvement in sucrose unloading. Expression profiling indicated high expression levels of the SWEET genes at the tuber apex, which progressively increased during tuber development, underscoring their critical roles in sucrose unloading, cell expansion, and biomass accumulation. These findings provide novel insights into the structural and functional mechanisms of the SWEET-mediated sucrose transport in yam, laying a solid foundation for future crop improvement strategies aiming to optimize sucrose distribution and enhance tuber yield and quality.