Involved in auxin biosynthesis. Belongs to the set of redundant YUCCA genes probably responsible for auxin biosynthesis in roots. H(+) + indole-3-pyruvate + NADPH + O2 = (indol-3-yl)acetate + CO2 + H2O + NADP(+) Plant hormone metabolism; auxin biosynthesis. Belongs to the FMO family.