This necrosis-inducing peptide induces a hypersensitive response on Cf-9 tomato genotypes. Race-specific elicitors are compounds which only induce defense responses in genotypes of host plants which are resistant to the pathogenic race that produces the elicitor, but not in susceptible genotypes. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin.