The Arabidopsis thaliana AGRAVITROPIC 1 gene encodes a component of the polar-auxin-transport efflux carrier

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 95; no. 25; pp. 15112 - 15117
• Main Authors: Chen, R. (University of Wisconsin, Madison.), Hilson, P, Sedbrook, J, Rosen, E, Caspar, T, Masson, P.H
• Format: Journal Article
• Language: English
• Published: Legacy CDMS National Academy of Sciences of the United States of America 08-12-1998; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences
• Subjects: AGR1 GENE; AIA; Alleles; Amino Acid Sequence; AMINO ACID SEQUENCES; Arabidopsis - genetics; Arabidopsis Proteins; ARABIDOPSIS THALIANA; ARN MENSAJERO; ARN MESSAGER; Auxins; Biological Sciences; Botany; Carrier Proteins - genetics; CARTE GENETIQUE; CELL MEMBRANES; CHEMICAL COMPOSITION; CHROMOSOME MAPS; Complementary DNA; COMPOSICION QUIMICA; COMPOSITION CHIMIQUE; EXPRESION GENICA; EXPRESSION DES GENES; FISIOLOGIA VEGETAL; Flowers & plants; GENBANK/AF087459; GENE; GENE EXPRESSION; GENES; Genes, Plant; GENETIC MAPPING; GENETIC MAPS; Genetic mutation; Genomics; Hormones; IAA; Life Sciences; Life Sciences (General); MAPAS GENETICOS; MEMBRANAS CELULARES; MEMBRANE CELLULAIRE; MESSENGER RNA; MOLECULAR SEQUENCE DATA; MUTANT; MUTANTES; MUTANTS; Mutation; NUCLEOTIDE SEQUENCE; Physical growth; PHYSIOLOGIE VEGETALE; PLANT PHYSIOLOGY; PLANT PROTEINS; Plant Proteins - genetics; Plant roots; Plants; PLASMA MEMBRANES; PROTEINAS; PROTEINE; PROTEINS; RACINE; RAICES; ROOT DISTAL ELONGATION ZONE; Root growth; ROOT TIPS; ROOTS; SACCHAROMYCES CEREVISIAE; SECUENCIA NUCLEOTIDICA; Seedlings; SEQUENCE NUCLEOTIDIQUE; STRUCTURAL GENES; Nasa Discipline Plant Biology; Non-Nasa Center; NASA Discipline Plant Biology; Non-NASA Center
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.95.25.15112

Auxins are plant hormones that mediate many aspects of plant growth and development. In higher plants, auxins are polarly transported from sites of synthesis in the shoot apex to their sites of action in the basal regions of shoots and in roots. Polar auxin transport is an important aspect of auxin functions and is mediated by cellular influx and efflux carriers. Little is known about the molecular identity of its regulatory component, the efflux carrier [Estelle, M. (1996) Current Biol. 6, 1589-1591]. Here we show that mutations in the Arabidopsis thaliana AGRAVITROPIC 1 (AGR1) gene involved in root gravitropism confer increased root-growth sensitivity to auxin and decreased sensitivity to ethylene and an auxin transport inhibitor, and cause retention of exogenously added auxin in root tip cells. We used positional cloning to show that AGR1 encodes a putative transmembrane protein whose amino acid sequence shares homologies with bacterial transporters. When expressed in Saccharomyces cerevisiae, AGR1 promotes an increased efflux of radiolabeled IAA from the cells and confers increased resistance to fluoro-IAA, a toxic IAA-derived compound. AGR1 transcripts were localized to the root distal elongation zone, a region undergoing a curvature response upon gravistimulation. We have identified several AGR1-related genes in Arabidopsis, suggesting a global role of this gene family in the control of auxin-regulated growth and developmental processes.