Two genetically discrete pathways convert tryptophan to auxin: more redundancy in auxin biosynthesis

The answer to the simple question of how plants make auxin has proven to be inordinately complex. Recent in planta studies in Arabidopsis have uncovered additional complexity in auxin biosynthesis. Two distinct pathways from tryptophan to the intermediate indole-acetaldoxime were identified. Genic, as well as functional redundancy, appear to be characteristic for auxin biosynthesis and plants might have evolved many different solutions for making and regulating auxin.