RanGAP1 and RanGAP2 are common virulence targets of two independently evolved effectors from the potato cyst nematode Globodera pallida and Potato Virus X

The closely related potato resistance genes Gpa2 and Rx1 encode canonical intracellular CC-NB-LRR immune receptors. They belong to the same R gene cluster, but evolved to defend against two unrelated pathogens. Gpa2 detects specific GpRbp-1 effector variants secreted by the potato cyst nematode Globodera pallida, whereas Rx1 recognizes the viral coat protein (CP) of Potato Virus X. How effector recognition by these receptors occurs has yet to be demonstrated. However, artificial tethering studies suggest that recognition may occur indirectly through the shared co-factor, Ran GTPase Activating Protein 2 (RanGAP2). Using a combination of Co-IP and cellular imaging studies, we could show that both the eliciting and non-eliciting variants of GpRbp-1 and PVX-CP can interact with RanGAP2 in planta through its WPP domain. Moreover, we could show that the RanGAP1 homolog can also associate with these effectors in the cell. From these data, we conclude that RanGAP1 and RanGAP2 are a common host target for two distinct pathogen effectors with a possible role in virulence. Interestingly, infection assays on mutants and TRV-VIGS silenced plants could show that RanGAP2 and RanGAP1 contribute to the pathogenicity of both cyst nematodes in Arabidopsis and PVX in N. benthamiana. From these data, a picture emerges that RanGAP1 and RanGAP2 are shared virulence targets of two evolutionary distinct pathogens, which are guarded by two closely related CC-NB-LRR immune receptors in potato.