Sugar Transporter <i>GmSWEET20</i> Contributes to the Resistance of Soybean to Cyst Nematode

SWEET (Sugars Will Eventually be Exported Transporter) proteins facilitate the movement of sugars through cell membranes and are essential for loading sucrose into phloem. Beyond its role in sugar transport, the SWEET protein also modulates plant resistance to various biotic and abiotic stresses. Among sugar transporter genes, <i>GmSWEET20</i> is a positive regulatory factor involved in soybean cyst nematode (<i>Heterodera glycines</i>) resistance. In this study, susceptible soybean cultivars (Williams 82) were used to conduct a transcriptome analysis to characterize the responses to nematode infection, in which multiple sugar transporter genes were highly expressed. The RT-qPCR analysis confirmed a significant increase in the expression of <i>GmSWEET20</i> in soybean roots with <i>H. glycines</i> infection. Heterologous expression tests indicated that the protein encoded by <i>GmSWEET20</i> does not transport hexose in yeast. Further analysis showed that soybean lines overexpressing <i>GmSWEET20</i> exhibited increased resistance to <i>H. glycines</i> compared with the control. A yeast one-hybrid assay was employed to discover that LOC114390362 binds to the <i>GmSWEET20</i> promoter. Transient expression in tobacco leaf cells revealed nucleus and cytosolic localization of LOC114390362. <i>LOC114390362</i>-overexpressing soybean lines showed a reduced number of nematode infections. Overall, the results indicate that the binding of LOC114390362 to the <i>GmSWEET20</i> promoter plays a positive role in regulating soybean resistance to <i>H. glycines</i>. The <i>GmSWEET20</i> gene has great potential to improve resistance to plant-parasitic nematodes in soybean and other plants.