Differential requirement for the EDS1 catalytic triad in A. thaliana and N. benthamiana

SummaryHeterodimeric complexes incorporating the lipase-like proteins EDS1 with PAD4 or SAG101 are central hubs in plant innate immunity. EDS1 functions encompass signal relay from TIR domain-containing intracellular NLR-type immune receptors (TNLs) towards RPW8-type helper NLRs (RNLs) and, inA. thaliana, bolstering of signaling and resistance mediated by cell-surface pattern recognition receptors (PRRs). Biochemical activities underlying these mechanistic frameworks remain unknown.We used CRISPR/Cas-generated mutant lines and agroinfiltration-based complementation assays to interrogate functions of EDS1 complexes inN. benthamiana.We do not detect impaired PRR signaling inN. benthamianalines deficient in EDS1 complexes or RNLs. Intriguingly, mutations within the catalytic triad ofSolanaceaeEDS1 can abolish or enhance TNL immunity inN. benthamiana. Furthermore, nuclear EDS1 accumulation is sufficient forN. benthamianaTNL (Roq1) immunity.Reinforcing PRR signaling in Arabidopsis might be a derived function of the TNL/EDS1 immune sector. Dependency ofSolanaceaebut notA. thalianaEDS1 on catalytic triad residues raises the possibility that a TNL-derived small molecule binds to theSolanaceaeEDS1 lipase-like domain, and that EDS1 lipase-like domain pocket contributions to TNL immune responses vary between lineages. Whether and how nuclear EDS1 activity connects to membrane pore-forming RNLs remains unknown.