PS Seminar Series- Immune signalling transduction from TIR-NLR resistance proteins to helper NLR proteins

Abstract - Plant resistance proteins act as immune receptors to recognise pathogen effectors and activate defense. Most resistance proteins encode intracellular receptors of the nucleotide-binding, leucine-rich repeat (NLR) class. Many NLRs contain a Toll-interleukin-1 receptor (TIR) domain that possess NADase catalytic activity is responsible for downstream signal transduction. Genetic dissection has revealed that these TIR-NLRs require two layers of downstream partners for immune function. The first layer includes three related proteins, the enhanced disease susceptibility 1 (EDS1), senescence associated gene 101 (SAG101) and phytoalexin-deficient 4 (PAD4) proteins, which function as two heterodimeric complexes EDS1/SAG101 and EDS1/PAD4. The second layer includes two helper NLRs, NRG1 and ADR1, which can function as plasma membrane calcium channels when activated. EDS1-SAG101 dimer and EDS1-PAD4 dimer work exclusively with NRG1 and ADR1 respectively and form two different signalling pathways. However, the mechanism of how immune signalling is transduced from TIR-NLRs to EDS1 family dimers and then to helper NLRs remains unclear. In this seminar, I will present that in N. benthamiana, TIR-NLRs only require EDS1-SAG101-NRG1 signalling pathway to mediated immunity. As the central regulator of signalling, the EDS1-SAG101 complex receives signalling directly from upstream TIR-NLRs by associating with the TIR domains through the N-terminal domains of both EDS1 and SAG101. Then signalling can be transferred to the downstream NRG1 by exclusive association of the C-terminal domain of SAG101 with the NB and LRR domain of NRG1.Our research contributes to the elucidation of the molecular mechanisms of TIR-NLRs proteins immunity activation and development of new strategies for crop protection.

Biography - I obtained my Master degree of science (major in biochemistry and molecular biology) in China Agricultural University (CAU). Then I came to Australia and started the PhD study with Prof. John Rathjen, Dr. Peter Dodds and Dr. Xiaoxiao Zhang since October 2017. My research is mainly focused on signalling function of plant disease resistance proteins, and the interaction between resistance proteins and effectors. I think study of the mechanism that underpinning the plant immunity is of great significance for crop protection.