title: Current aspects of auxin biosynthesis in plants.
abstract: Auxin is an important plant hormone essential for many aspects of plant growth and development. Indole-3-acetic acid (IAA) is the most studied auxin in plants, and its biosynthesis pathway has been investigated for over 70 years. Although the complete picture of auxin biosynthesis remains to be elucidated, remarkable progress has been made recently in understanding the mechanism of IAA biosynthesis. Genetic and biochemical studies demonstrate that IAA is mainly synthesized from l-tryptophan (Trp) via indole-3-pyruvate by two-step reactions in Arabidopsis. While IAA is also produced from Trp via indole-3-acetaldoxime in Arabidopsis, this pathway likely plays an auxiliary role in plants of the family Brassicaceae. Recent studies suggest that the Trp-independent pathway is not a major route for IAA biosynthesis, but they reveal an important role for a cytosolic indole synthase in this pathway. In this review, I summarize current views and future prospects of IAA biosynthesis research in plants.
authors.affiliation: a RIKEN Center for Sustainable Resource Science , Yokohama , Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kasahara
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D053898:Biosynthetic Pathways / Q000235:genetics; D019607:Brassicaceae / Q000235:genetics / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism*; D007211:Indoles / Q000378:metabolism; D008025:Ligases / Q000235:genetics / Q000378:metabolism; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism; D010091:Oximes / Q000378:metabolism; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism; D063245:Plant Development / Q000235:genetics*; D010937:Plant Growth Regulators / Q000378:metabolism*; D011773:Pyruvates / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D007211:Indoles; D010091:Oximes; D010937:Plant Growth Regulators; D011773:Pyruvates; C467098:indole-3-acetaldoxime; C030737:indoleacetic acid; D014364:Tryptophan; D003577:Cytochrome P-450 Enzyme System; C530432:cytochrome P-450 79B2 protein, Arabidopsis; D010105:Oxygenases; C422746:YUC protein, Arabidopsis; C507996:IAMT1 protein, Arabidopsis; D008780:Methyltransferases; C525277:GH3.5 protein, Arabidopsis; D008025:Ligases
keywords: TAA; YUCCA; auxin; biosynthesis; indole-3-acetic acid