Mechanisms of NRC immune receptor network modulation by an atypical NLR protein

• Applicant: Dr. Daniel Lüdke
• Subject Area: Plant Breeding and Plant Pathology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 464864389

The induction of a programmed cell death, termed hypersensitive response (HR), is a major defense mechanism of plants to confer pathogen resistance. HR can be induced by intracellular nucleotide-binding leucine-rich repeat (NLR) receptors upon detection of pathogen secreted molecules, known as effectors. The NLR-REQUIRED FOR CELL DEATH (NRC) superclade in Solanaceae plant species forms extensive networks of functionally dependent NLRs. NRCs either function in effector sensing (NRC-sensors) or cell death execution (NRC-helpers) and confer robust HR-based resistance against multiple pathogens that challenge diverse plant tissues. Plants require tight transcriptional regulation and homeostasis between NLR receptors to prevent inadvertent activation that comes with high fitness costs. Previous analyses identified NRCX as an atypical NRC family member that contributes to network homeostasis by modulating the functionality of other NRC-helpers during plant growth and immunity. NRCX appears to have specialized in this regulatory function and has lost the capacity of executing the HR. The transcriptional regulation and the mechanism by which the NRC network components are modulated by NRCX to maintain network homeostasis are unknown. I propose the hypothesis that NRCs and NRCX are transcriptionally co-regulated in a tissue-specific manner to allow for the formation of robust sub-networks, and that homeostasis is maintained by direct interaction of NRCX with network components required for the induction of a cell death response. To identify NRCX interactors, I will employ proximity-labeling approaches coupled to mass spectrometry. This will also help to elucidate NRC network components that might be required for HR induction. To explore the tissue-specific transcriptional regulation of NRCX and NRC sub-networks, tissue-specific expression datasets of pathogen challenged and unchallenged leaves and roots will be generated using a transcriptomics approach. The proposed project will advance our knowledge of plant innate immunity and contribute to the development of effective breeding strategies of disease resistance traits in crop plants.

• DFG Programme: WBP Fellowship
• International Connection: United Kingdom
• Host: Professor Sophien Kamoun, Ph.D.