Roles and mechanisms of helper NLR phosphorylation in plant immunity

Plant diseases caused by microbes result in considerable yield losses in agricultural production systems worldwide, thereby endangering food security. To combat invading microbes, plants have evolved a two-layered innate immune detection system: cell-surface receptor-initiated pattern-triggered immunity (PTI) and intracellular nucleotide-binding leucine-rich repeat receptor (NLR)-initiated effector-triggered immunity (ETI). Interestingly, cell-surface receptors are required for full NLR-mediated plant immunity. NLRs are classified as sensor NLRs, involved in effector detection, or helper NLRs, required for sensor NLR signalling. Our preliminary data demonstrate that in Arabidopsis thaliana the helper NLR N REQUIREMENT GENE 1 (NRG1) undergoes PTI-dependent phosphorylation, which plays an important role in NRG1-mediated programmed cell death. This suggests that helper NLR phosphorylation may be a crucial checkpoint for PTI/ETI mutual potentiation. This project aims to unravel the molecular mechanisms by which NRG1 is phosphorylated and how its phosphorylation potentiates NLR-initiated immune signalling. My host institute, the Sainsbury Laboratory (TSL), has all the resources to carry out this research. During my work supported by this fellowship, I will be trained in molecular biology, biochemistry, genetics, proteomics and bioinformatics, which will lay the foundation for my future career as an independent researcher. In turn, I will bring my specific expertise in phosphorylation-based activation of cell-surface receptor complexes in Nicotiana benthamiana and tomato, which is not currently available in my host lab. The findings of this project will advance the understanding of plant-microbe interactions and should provide new strategies for crop protection and plant breeding. Furthermore, I will be equipped with the skills and experience necessary to position myself as a leading independent researcher.