Involved in auxin biosynthesis (PubMed:17220367, PubMed:29740464). Converts the indole-3-pyruvic acid (IPA) produced by the TAA family to indole-3-acetic acid (IAA) (Probable). Functions downstream of TAR2 in auxin biosynthesis (PubMed:29740464). Functions upstream of WOX11, a transcription factor that promotes the development of crown roots (PubMed:29740464). H(+) + indole-3-pyruvate + NADPH + O2 = (indol-3-yl)acetate + CO2 + H2O + NADP(+) Expressed in coleoptile tips, root tips, leaf blade tips, shoot apical meristem, vasculature of stems and flowers. Calli overexpressing YUCCA1 exhibit high levels of auxin, low regeneration frequency, overgrowing roots, and abnormal root morphology (PubMed:17220367, PubMed:29740464). Plants silencing YUCCA1 exhibit severe dwarfism, inhibition of shoot elongation and root formation and elongation (PubMed:17220367). Belongs to the FMO family.