Dissecting Gpa2-mediated immune signaling pathways involved in resistance to the potato cyst nematode Globodera pallida

Potato resistance gene Gpa2 encodes a CC-NB-LRR protein, which confers resistance against potato cyst nematodes G. pallida. Gpa2 recognize variants of secretory protein RBP-1 from G. pallida. It is revealed that RBP-1 recognition is determined by C-terminus of LRR domain of Gpa2. However, there is no physical interaction between LRR domain and RBP-1. It is assumed that an indirect recognition model is applied in which Gpa2 may perceive RBP-1 within the help of other cellular host factors. As the close homologue of Gpa2, Rx1 confers resistance to Potato Virus X (PVX). Although they show high sequence similarity, they confer resistance to two distinct pathogens, which provides a model to study mechanism involves in pathogen recognition and NB-LRR immune activation. The fact that a close cooperation between NB-ARC and N-terminal of LRR domains in controlling activity of immune receptor is found by extensive sequence exchange. The CC domain of NB-LRR immune receptors is considered to be involved in indirect pathogen recognition and induction of downstream signaling. The LRR domain is thought to be involved in pathogen detection and controlling resting state of protein. Although basic structural function is known about Gpa2, molecular mechanism and pathways involved in Gpa2-mediated resistance still remains vague. The aim of this project is to dissect Gpa2-mediated activation mechanism and immune signaling pathways involved in plant resistance against potato cyst nematode G. pallida.