The R protein Roq1 mediates recognition of Xanthomonas and Pseudomonas effector proteins XopQ and HopQ1 in the Nicotiana genus (Schultink et al., 2017), whereas in Arabidopsis, a genetic interaction between Qpm3.1 and hopW1-1 determines resistance to bacterial infection (Luo et al., 2017). Here, PROS1 is linked to bacterial infectious disease.