An isolated peptide that is 12 to 50 amino acids in length, the peptide comprising the amino acid sequence of (i) L-X-X-L-L-L-X-(F/L)-(I/L)-X-X-X-L (SEQ ID NO: 2) wherein X at position 2 is selected from Glu, γ-glutamate, Asp, and isoD; X at position 3 is optional and, when present, is Gln; and each X at positions 7, 10, 11, and 12 is independently selected from Met, Ala, Glu, and γ-glutamate; or (ii) wherein X at position 4 is selected from Glu, γ-glutamate, Asp, and isoD; X at position 5 is optional and, when present, is Gln, and each X at positions 9, 12, 13, and 14 is independently selected from Met, Ala, Glu, and γ-glutamate; or (iii) wherein X at position 2 is selected from Glu, γ-glutamate, Asp, and isoD; X at position 3 is optional and, when present, is Gln, and each X at positions 7, 10, 11, and 12 is independently selected from Met, Ala, Glu, and γ-glutamate; or (iv) wherein X at position 4 is selected from Glu, γ-glutamate, Asp, and isoD; X at position 5 is optional and, when present, is Gln, and each X at positions 9, 12, 13, and 14 is independently selected from Met, Ala, Glu, and γ-glutamate; wherein the peptide induces an active plant response when applied to plant tissue, and optionally induces a hypersensitive response. (i) L-X-X-L-L-L-X-(F/L)-(I/L)-X-X-X-L (SEQ ID NO: 2) wherein X at position 2 is selected from Glu, γ-glutamate, Asp, and isoD; X at position 3 is optional and, when present, is Gln; and each X at positions 7, 10, 11, and 12 is independently selected from Met, Ala, Glu, and γ-glutamate; or X at position 2 is selected from Glu, γ-glutamate, Asp, and isoD; X at position 3 is optional and, when present, is Gln; and each X at positions 7, 10, 11, and 12 is independently selected from Met, Ala, Glu, and γ-glutamate; or (ii) wherein X at position 4 is selected from Glu, γ-glutamate, Asp, and isoD; X at position 5 is optional and, when present, is Gln, and each X at positions 9, 12, 13, and 14 is independently selected from Met, Ala, Glu, and γ-glutamate; or X at position 4 is selected from Glu, γ-glutamate, Asp, and isoD; X at position 5 is optional and, when present, is Gln, and each X at positions 9, 12, 13, and 14 is independently selected from Met, Ala, Glu, and γ-glutamate; or (iii) wherein X at position 2 is selected from Glu, γ-glutamate, Asp, and isoD; X at position 3 is optional and, when present, is Gln, and each X at positions 7, 10, 11, and 12 is independently selected from Met, Ala, Glu, and γ-glutamate; or X at position 2 is selected from Glu, γ-glutamate, Asp, and isoD; X at position 3 is optional and, when present, is Gln, and each X at positions 7, 10, 11, and 12 is independently selected from Met, Ala, Glu, and γ-glutamate; or (iv) wherein X at position 4 is selected from Glu, γ-glutamate, Asp, and isoD; X at position 5 is optional and, when present, is Gln, and each X at positions 9, 12, 13, and 14 is independently selected from Met, Ala, Glu, and γ-glutamate; wherein the peptide induces an active plant response when applied to plant tissue, and optionally induces a hypersensitive response. X at position 4 is selected from Glu, γ-glutamate, Asp, and isoD; X at position 5 is optional and, when present, is Gln, and each X at positions 9, 12, 13, and 14 is independently selected from Met, Ala, Glu, and γ-glutamate; wherein the peptide induces an active plant response when applied to plant tissue, and optionally induces a hypersensitive response.