Endogenous secreted peptide that acts as elicitor of immune response and positive regulator of defense response. Amplifies the immune response triggered by flg22, the active epitope of bacterial flagellin. Acts as negative regulator of root growth. Expressed in guard cells, hydathodes, leaf trichomes, and vascular tissues of leaves and roots. Induced by infection with the bacterial pathogen Pseudomonas syringae pv tomato strain DC3000 and the fungal pathogen Fusarium oxysporum conglutinans strain 699. Induced by the flagellin flg22, chitin elicitor and salicylate. Contains 4-hydroxyproline; hydroxylated on Pro-65 and Pro-67. Extended C-terminus. Truncated N-terminus. Truncated N-terminus.