Group I, II and III mutants were tested for resistance mediated by the TNL pair RRS1 and RPS4 (TNLRRS1–RPS4) to Pst avrRps4 infection in leaves, measured against wild-type Col-0 (Col, resistant), an rrs1a rrs1b (rrs1ab) mutant defective specifically in TNLRRS1–RPS4 ETI36, as well as eds1 and an a3 n2 ‘helperless’ mutant which are both fully susceptible to Pst avrRps412,19,25,26. This evidence concerns the gene RRS1 and infection.