title: Auxin Biosynthesis: Are the Indole-3-Acetic Acid and Phenylacetic Acid Biosynthesis Pathways Mirror Images?
abstract: The biosynthesis of the main auxin in plants (indole-3-acetic acid [IAA]) has been elucidated recently and is thought to involve the sequential conversion of Trp to indole-3-pyruvic acid to IAA However, the pathway leading to a less well studied auxin, phenylacetic acid (PAA), remains unclear. Here, we present evidence from metabolism experiments that PAA is synthesized from the amino acid Phe, via phenylpyruvate. In pea (Pisum sativum), the reverse reaction, phenylpyruvate to Phe, is also demonstrated. However, despite similarities between the pathways leading to IAA and PAA, evidence from mutants in pea and maize (Zea mays) indicate that IAA biosynthetic enzymes are not the main enzymes for PAA biosynthesis. Instead, we identified a putative aromatic aminotransferase (PsArAT) from pea that may function in the PAA synthesis pathway.
authors.affiliation: School of Biological Sciences (S.D.C., E.L.M., L.Q., J.J.R.), Central Science Laboratory (D.S.N.), School of Chemistry (J.S.), University of Tasmania, Sandy Bay, Tasmania, Australia, 7005; and U.S. Department of Agriculture, Agricultural Research Service, Gainesville, Florida 32608 (P.S.C.).
authors.forename: Sam D
authors.identifier: 0000-0003-0950-6131
authors.initials: SD
authors.lastname: Cook
authors.affiliation: School of Biological Sciences (S.D.C., E.L.M., L.Q., J.J.R.), Central Science Laboratory (D.S.N.), School of Chemistry (J.S.), University of Tasmania, Sandy Bay, Tasmania, Australia, 7005; and U.S. Department of Agriculture, Agricultural Research Service, Gainesville, Florida 32608 (P.S.C.).
authors.forename: David S
authors.initials: DS
authors.lastname: Nichols
authors.affiliation: School of Biological Sciences (S.D.C., E.L.M., L.Q., J.J.R.), Central Science Laboratory (D.S.N.), School of Chemistry (J.S.), University of Tasmania, Sandy Bay, Tasmania, Australia, 7005; and U.S. Department of Agriculture, Agricultural Research Service, Gainesville, Florida 32608 (P.S.C.).
authors.forename: Jason
authors.initials: J
authors.lastname: Smith
authors.affiliation: School of Biological Sciences (S.D.C., E.L.M., L.Q., J.J.R.), Central Science Laboratory (D.S.N.), School of Chemistry (J.S.), University of Tasmania, Sandy Bay, Tasmania, Australia, 7005; and U.S. Department of Agriculture, Agricultural Research Service, Gainesville, Florida 32608 (P.S.C.).
authors.forename: Prem S
authors.initials: PS
authors.lastname: Chourey
authors.affiliation: School of Biological Sciences (S.D.C., E.L.M., L.Q., J.J.R.), Central Science Laboratory (D.S.N.), School of Chemistry (J.S.), University of Tasmania, Sandy Bay, Tasmania, Australia, 7005; and U.S. Department of Agriculture, Agricultural Research Service, Gainesville, Florida 32608 (P.S.C.).
authors.forename: Erin L
authors.initials: EL
authors.lastname: McAdam
authors.affiliation: School of Biological Sciences (S.D.C., E.L.M., L.Q., J.J.R.), Central Science Laboratory (D.S.N.), School of Chemistry (J.S.), University of Tasmania, Sandy Bay, Tasmania, Australia, 7005; and U.S. Department of Agriculture, Agricultural Research Service, Gainesville, Florida 32608 (P.S.C.).
authors.forename: Laura
authors.initials: L
authors.lastname: Quittenden
authors.affiliation: School of Biological Sciences (S.D.C., E.L.M., L.Q., J.J.R.), Central Science Laboratory (D.S.N.), School of Chemistry (J.S.), University of Tasmania, Sandy Bay, Tasmania, Australia, 7005; and U.S. Department of Agriculture, Agricultural Research Service, Gainesville, Florida 32608 (P.S.C.) john.ross@utas.edu.au.
authors.forename: John J
authors.identifier: 0000-0003-3665-2062
authors.initials: JJ
authors.lastname: Ross
mesh_terms: D053898:Biosynthetic Pathways; D002851:Chromatography, High Pressure Liquid; D057075:Enzyme Assays; D017343:Genes, Plant; D007210:Indoleacetic Acids / Q000378:metabolism*; D007211:Indoles / Q000378:metabolism; D013058:Mass Spectrometry; D009154:Mutation / Q000235:genetics; D018532:Pisum sativum / Q000235:genetics / Q000378:metabolism; D010648:Phenylacetates / Q000378:metabolism*; D010649:Phenylalanine / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism; D003313:Zea mays / Q000235:genetics / Q000378:metabolism
chemical_list: D007210:Indoleacetic Acids; D007211:Indoles; D010648:Phenylacetates; D010940:Plant Proteins; D010649:Phenylalanine; C008122:indol-3-yl pyruvic acid; C030737:indoleacetic acid; D014364:Tryptophan; C025136:phenylacetic acid