A truncated CC-NB-ARC gene TaRPP13L1-3D positively regulates powdery mildew resistance in wheat via the RanGAP-WPP complex-mediated nucleocytoplasmic shuttle

Main Conclusion A wheat RPP13-like isoform interacting with WPP1 contributes to quantitative and/or basal resistance to powdery mildew ( Blumeria graminis f. sp. tritici ) by restricting the development of Bgt conidia. Abstract Plant disease resistance ( R ) genes confer an ability to resist infection by pathogens expressing specific avirulence genes. Recognition of Peronospora parasitica 13-like ( RPP13-like ) genes belong to the nucleotide-binding site and leucine-rich repeat (NBS-LRR) superfamily and play important roles in resistance to various plant diseases. Previously, we detected a TaRPP13 -like gene located on chromosome 3D ( TaRPP13L1-3D ) in the TaSpl1 resided region, which is strongly induced by the cell death phenotype (Zhang et al. 2021). Here, we investigated the expression and functional role of TaRPP13L1-3D in wheat responding to fungal stress. TaRPP13L1-3D encoded a typical NB-ARC structure characterized by Rx-N and P-loop NTPase domains. TaRPP13L1-3D transcripts were strongly upregulated in wheat by powdery mildew ( Blumeria graminis f. sp. tritici ; Bgt ) and stripe rust ( Puccinia striiformis f. sp. tritici ; Pst ) infection although opposing expression patterns were observed in response to wheat- Bgt in incompatible and compatible backgrounds. Overexpression of TaRPP13L1-3D enhanced disease resistance to Bgt , accompanied by upregulation of the defense-related marker genes encoding phytoalexin-deficient4 ( PAD4 ), thaumatin-like protein ( TLP ) and chitinase 8-like protein ( Chi8L ), while silencing of TaRPP13L1-3D disrupted the resistance to Bgt infection. Subcellular localization studies showed that TaRPP13L1-3D is located in both the plasma membrane and nucleus, while yeast-two-hybrid (Y2H) assays indicated that TaRPP13L1-3D interacts with WPP domain-containing protein 1 (TaWPP1). This indicates that TaRPP13L1-3D shuttles between the nucleus and cytoplasm membrane via a mechanism that is mediated by the RanGAP-WPP complex in nuclear pores. This insight into TaRPP13L1-3D will be useful in dissecting the mechanism of fungal resistance in wheat, and understanding the interaction between R gene expression and pathogen defense.