Plant Toll/interleukin-1 receptor/resistance protein domains physically associate with enhanced disease susceptibility1 family proteins in immune signaling
Jian Chen, Xiaoxiao Zhang, Maud Bernoux, John P. Rathjen, Peter N. Dodds
Abstract
Plant Toll/interleukin-1 receptor/resistance protein (TIR) type nucleotide-binding and leucine-rich repeat immune receptors (NLRs) require enhanced disease susceptibility 1 (EDS1) family proteins and the helper NLRs NRG1 and ADR1 for immune activation. We show that the Nb EDS1- Nb SAG101b- Nb NRG1 signaling pathway in N. benthamiana is necessary for cell death signaling by TIR-NLRs from a range of plant species, suggesting a universal requirement for this module in TIR-NLR-mediated cell death in N. benthamiana. We also find that TIR domains physically associate with Nb EDS1, Nb PAD4, and Nb SAG101 in planta , independently of each other. Furthermore, Nb NRG1 associates with Nb SAG101b, but not with other EDS1 family members, via its C-terminal EP domain. Physical interaction between activated TIRs and EDS1 signaling complexes may facilitate the transfer of low abundance products of TIR catalytic activity or alter TIR catalytic activity to favor the production of EDS1 heterodimer ligands.