Balanced nuclear and cytoplasmic distribution is required for activation of Gpa2-mediated resistance against potato cyst nematode Globodera pallida

The resistance gene Gpa2 encodes a CC-NB-LRR protein in potato and confers resistance to the potato cyst nematode Globodera pallida. Gpa2 is able to recognize specific variants of the secretory effector protein RBP-1 from G. pallida. The activation of Gpa2-mediated cell death requires RanGAP2, which is known as an interactor of the Gpa2 CC domain. RanGAP2 serves as a cytoplasmic retention factor of the close homologue Rx1, which confers resistance to Potato Virus X. However, the effect of RanGAP2 on the nucleocytoplasmic distribution of Gpa2 in plant cells and how this contributes to Gpa2-mediated resistance remains unclear. Here, we show that Gpa2 has a nucleocytoplasmic distribution pattern despite the absence of canonical nuclear localization signals similar to Rx1. Cytoplasmic or nuclear targeted Gpa2 shows a reduced cell death response, suggesting that both the cytoplasmic and nuclear compartment are required for Gpa2-mediated cell death response. Besides, nuclear targeted RBP-1 results in loss of Gpa2-mediated cell death, which indicates that RBP-1 recognition takes place in the cytoplasm. Currently, we are exploring the role of RanGAP2 in the balanced nucleocytoplasmic partitioning of Gpa2 pre- and post activation by RBP-1. Co-localization studies complemented with structure-informed approaches on complex formation among Gpa2, RBP-1 and RanGAP2 will give us more insights about how RanGAP2 is involved in Gpa2-mediated resistance