Stripe rust fungi hijack a host transcriptional repressor to induce TaSWEET14d for enhanced sugar uptake in wheat

Biotrophic pathogens rely on host plants for carbon acquisition, making plant sugar transporters, such as Sugars Will Eventually be Exported Transporters (SWEETs), key targets in sugar competition between plants and pathogens. In this study, we identified TaSWEET14d as a Puccinia striiformis f. sp. tritici (Pst)-induced, secretory vesicle-localized SWEET family member that facilitates hexose and sucrose translocation in wheat. Knockout of TaSWEET14d led to enhanced wheat resistance to Pst, while overexpressing TaSWEET14d promoted susceptibility to stripe rust and sugar accumulation in wheat leaves. In addition, wheat transcription factor TaMYB50 contributed to stripe rust resistance by suppressing TaSWEET14d expression through binding directly to the TA-box motif in the promoter region. Furthermore, we found that effector protein Pst15882, required for Pst infection and pathogenicity, interacted with TaMYB50 to prevent this repression, thus revealing a distinctive regulation strategy by Pst to exploit host sugars for fungal invasion.