High levels in roots and not detectable in hypocotyls, cotyledons, stems, leaves and flower buds of untreated plants. After induction, high levels are present in the vascular bundles of leaves. It appears in leaves 3 hours after induction, maximum levels are reached by 24 hours and remain at a high level over a period of at least 72 hours. Upon contact with the plant pathogen Pseudomonas syringae pv pisi and salicylic acid. Belongs to the BetVI family.