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.
Bibliographical noteFunding Information:
Work in our laboratories on auxin metabolism has been supported by grant DE-A102–94ER20153 from the US Department of Energy, by a USDA National Needs fellowship to A.M.H., the Minnesota Agricultural Experiment Station, the Gordon and Margaret Bailey Endowment for Environmental Horticulture, and by funds from the US Department of Agriculture Agricultural Research Service.