title: Local auxin metabolism regulates environment-induced hypocotyl elongation.
abstract: A hallmark of plants is their adaptability of size and form in response to widely fluctuating environments. The metabolism and redistribution of the phytohormone auxin play pivotal roles in establishing active auxin gradients and resulting cellular differentiation. In Arabidopsis thaliana, cotyledons and leaves synthesize indole-3-acetic acid (IAA) from tryptophan through indole-3-pyruvic acid (3-IPA) in response to vegetational shade. This newly synthesized auxin moves to the hypocotyl where it induces elongation of hypocotyl cells. Here we show that loss of function of VAS2 (IAA-amido synthetase Gretchen Hagen 3 (GH3).17) leads to increases in free IAA at the expense of IAA-Glu (IAA-glutamate) in the hypocotyl epidermis. This active IAA elicits shade- and high temperature-induced hypocotyl elongation largely independently of 3-IPA-mediated IAA biosynthesis in cotyledons. Our results reveal an unexpected capacity of local auxin metabolism to modulate the homeostasis and spatial distribution of free auxin in specialized organs such as hypocotyls in response to shade and high temperature.
authors.affiliation: Howard Hughes Medical Institute and Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA.
authors.forename: Zuyu
authors.initials: Z
authors.lastname: Zheng
authors.affiliation: The Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA.
authors.forename: Yongxia
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.|Laboratory of Growth Regulators, Faculty of Science, Palacký University and Institute of Experimental Botany ASCR, Šlechtielů 11, 783 71 Olomouc, Czech Republic.
authors.forename: Ondřej
authors.initials: O
authors.lastname: Novák
authors.affiliation: Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA.
authors.forename: William
authors.initials: W
authors.lastname: Chen
authors.affiliation: Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.
authors.forename: Karin
authors.identifier: 0000-0003-2901-189X
authors.initials: K
authors.lastname: Ljung
authors.affiliation: Howard Hughes Medical Institute and The Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA, Czech Republic.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Noel
authors.affiliation: Howard Hughes Medical Institute and Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA.
authors.forename: Joanne
authors.initials: J
authors.lastname: Chory
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D001692:Biological Transport; D053898:Biosynthetic Pathways / Q000235:genetics; D018548:Cotyledon / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics; D004777:Environment; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005966:Glucuronidase / Q000378:metabolism; D018546:Hypocotyl / Q000254:growth & development* / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D019441:Plant Epidermis / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D013696:Temperature
chemical_list: D007210:Indoleacetic Acids; D018749:RNA, Plant; D005966:Glucuronidase