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. Contains 4-hydroxyproline; hydroxylated on Pro-77 and Pro-79. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus.