Identification of an aromatic aldehyde synthase involved in indole-3-acetic acid biosynthesis in the galling sawfly (Pontania sp.) and screening of an inhibitor

Indole-3-acetic acid (IAA), a phytohormone auxin, may be involved in insect gall induction. We previously proposed that the IAA biosynthetic pathway is Trp → indole-3-acetaldoxime indole-3-acetaldehyde (IAAld) or IAAld IAA. In this study, we surveyed galling sawfly enzymes responsible for rate-limiting steps using heterologous protein expression system and identified PonAAS2, an aromatic aldehyde synthase, catalyzed conversion of to IAAld. The PonAAS2 gene was highly expressed early- mid-stage larvae contained high concentrations IAA, but level almost negligible had escaped from their autumn very low An inhibitor obtained by screening chemical library, inhibited production enzyme solution 80%, suggesting important role biosynthesis sawfly.