Acetyltransferase that converts ornithine to N5-acetylornithine, which is likely used in plant defense. By methyl jasmonate, and wounding by the aphid M.persicae, and the lepidopteran herbivores P.rapae (white cabbage butterfly) and P.xylostella (diamondback moth). No visible phenotype under normal growth conditions, but mutant plants are unable to produce N5-acetylornithine in response to methyl jasmonate. Belongs to the acetyltransferase family.