Structure-function analyses of coiled-coil immune receptors define a hydrophobic module for improving plant virus resistance.

Plant immunity relies on nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) that detect microbial patterns released by pathogens and activate localized cell death to prevent the spread of pathogens. Tsw is the only identified resistance (R) gene encoding an NLR conferring resistance against tomato spotted wilt orthotospovirus (TSWV) in pepper species (Capsicum, Solanaceae). However, molecular and cellular mechanisms of Tsw-mediated resistance are still elusive. Here, we analyzed the structural and cellular-functional features of Tsw protein and defined a hydrophobic module to improve NLR-mediated virus resistance. The plasma-membrane associated N-terminal 137 amino acid in the coiled-coil (CC) domain of Tsw is the minimum fragment sufficient to trigger cell death in Nicotiana benthamiana plant. Transient and transgenic expression assays in plants indicated that the amino acid of the hydrophobic groove (134 th-137 th amino acid) in the CC domain is critical for its full functions and can be modified for enhanced disease resistance. Based on the structural features of Tsw, a super-hydrophobic funnel-like mutant Tsw Y137W was identified to confer higher resistance against TSWV with SGT1-dependent manner. The same point mutation in a tomato Tsw-like NLR protein improved the resistance as well, suggesting a feasible way of structure-assisted improvements of NLR against pathogens.