title: SHADE AVOIDANCE 4 Is Required for Proper Auxin Distribution in the Hypocotyl.
abstract: The phytohormone auxin is involved in virtually every aspect of plant growth and development. Through polar auxin transport, auxin gradients can be established, which then direct plant differentiation and growth. Shade avoidance responses are well-known processes that require polar auxin transport. In this study, we have identified a mutant, shade avoidance 4 (sav4), defective in shade-induced hypocotyl elongation and basipetal auxin transport. SAV4 encodes an unknown protein with armadillo repeat- and tetratricopeptide repeat-like domains known to provide protein-protein interaction surfaces. C terminally yellow fluorescent protein-tagged SAV4 localizes to both the plasma membrane and the nucleus. Membrane-localized SAV4 displays a polar association with the shootward plasma membrane domain in hypocotyl and root cells, which appears to be necessary for its function in hypocotyl elongation. Cotransfection of SAV4 and ATP-binding cassette B1 (ABCB1) auxin transporter in tobacco (Nicotiana benthamiana) revealed that SAV4 blocks ABCB1-mediated auxin efflux. We thus propose that polarly localized SAV4 acts to inhibit ABCB-mediated auxin efflux toward shoots and facilitates the establishment of proper auxin gradients.
authors.affiliation: School of Life Sciences, Xiamen Plant Genetics Key Laboratory (Y.G., F.Y., M.W., Y.T.), and State Key Laboratory of Cellular Stress Biology (Y.G., Y.T.), Xiamen University, Xiamen 361102, China.|Department of Plant Systems Biology, Technische Universität München, Freising 85354, Germany (M.Z., C.S.).|Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden (K.L.).|Department of Cell Biology and Plant Biochemistry, Universität Regensburg, Regensburg 93047, Germany (A.F., U.Z.H.); and.|Department of Biology-Plant Biology, University of Fribourg, CH-1700 Fribourg, Switzerland (M.D.D., M.G.).
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Ge
authors.affiliation: School of Life Sciences, Xiamen Plant Genetics Key Laboratory (Y.G., F.Y., M.W., Y.T.), and State Key Laboratory of Cellular Stress Biology (Y.G., Y.T.), Xiamen University, Xiamen 361102, China.|Department of Plant Systems Biology, Technische Universität München, Freising 85354, Germany (M.Z., C.S.).|Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden (K.L.).|Department of Cell Biology and Plant Biochemistry, Universität Regensburg, Regensburg 93047, Germany (A.F., U.Z.H.); and.|Department of Biology-Plant Biology, University of Fribourg, CH-1700 Fribourg, Switzerland (M.D.D., M.G.).
authors.forename: Fenglian
authors.initials: F
authors.lastname: Yan
authors.affiliation: School of Life Sciences, Xiamen Plant Genetics Key Laboratory (Y.G., F.Y., M.W., Y.T.), and State Key Laboratory of Cellular Stress Biology (Y.G., Y.T.), Xiamen University, Xiamen 361102, China.|Department of Plant Systems Biology, Technische Universität München, Freising 85354, Germany (M.Z., C.S.).|Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden (K.L.).|Department of Cell Biology and Plant Biochemistry, Universität Regensburg, Regensburg 93047, Germany (A.F., U.Z.H.); and.|Department of Biology-Plant Biology, University of Fribourg, CH-1700 Fribourg, Switzerland (M.D.D., M.G.).
authors.forename: Melina
authors.initials: M
authors.lastname: Zourelidou
authors.affiliation: School of Life Sciences, Xiamen Plant Genetics Key Laboratory (Y.G., F.Y., M.W., Y.T.), and State Key Laboratory of Cellular Stress Biology (Y.G., Y.T.), Xiamen University, Xiamen 361102, China.|Department of Plant Systems Biology, Technische Universität München, Freising 85354, Germany (M.Z., C.S.).|Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden (K.L.).|Department of Cell Biology and Plant Biochemistry, Universität Regensburg, Regensburg 93047, Germany (A.F., U.Z.H.); and.|Department of Biology-Plant Biology, University of Fribourg, CH-1700 Fribourg, Switzerland (M.D.D., M.G.).
authors.forename: Meiling
authors.initials: M
authors.lastname: Wang
authors.affiliation: School of Life Sciences, Xiamen Plant Genetics Key Laboratory (Y.G., F.Y., M.W., Y.T.), and State Key Laboratory of Cellular Stress Biology (Y.G., Y.T.), Xiamen University, Xiamen 361102, China.|Department of Plant Systems Biology, Technische Universität München, Freising 85354, Germany (M.Z., C.S.).|Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden (K.L.).|Department of Cell Biology and Plant Biochemistry, Universität Regensburg, Regensburg 93047, Germany (A.F., U.Z.H.); and.|Department of Biology-Plant Biology, University of Fribourg, CH-1700 Fribourg, Switzerland (M.D.D., M.G.).
authors.forename: Karin
authors.identifier: 0000-0003-2901-189X
authors.initials: K
authors.lastname: Ljung
authors.affiliation: School of Life Sciences, Xiamen Plant Genetics Key Laboratory (Y.G., F.Y., M.W., Y.T.), and State Key Laboratory of Cellular Stress Biology (Y.G., Y.T.), Xiamen University, Xiamen 361102, China.|Department of Plant Systems Biology, Technische Universität München, Freising 85354, Germany (M.Z., C.S.).|Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden (K.L.).|Department of Cell Biology and Plant Biochemistry, Universität Regensburg, Regensburg 93047, Germany (A.F., U.Z.H.); and.|Department of Biology-Plant Biology, University of Fribourg, CH-1700 Fribourg, Switzerland (M.D.D., M.G.).
authors.forename: Astrid
authors.initials: A
authors.lastname: Fastner
authors.affiliation: School of Life Sciences, Xiamen Plant Genetics Key Laboratory (Y.G., F.Y., M.W., Y.T.), and State Key Laboratory of Cellular Stress Biology (Y.G., Y.T.), Xiamen University, Xiamen 361102, China.|Department of Plant Systems Biology, Technische Universität München, Freising 85354, Germany (M.Z., C.S.).|Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden (K.L.).|Department of Cell Biology and Plant Biochemistry, Universität Regensburg, Regensburg 93047, Germany (A.F., U.Z.H.); and.|Department of Biology-Plant Biology, University of Fribourg, CH-1700 Fribourg, Switzerland (M.D.D., M.G.).
authors.forename: Ulrich Z
authors.initials: UZ
authors.lastname: Hammes
authors.affiliation: School of Life Sciences, Xiamen Plant Genetics Key Laboratory (Y.G., F.Y., M.W., Y.T.), and State Key Laboratory of Cellular Stress Biology (Y.G., Y.T.), Xiamen University, Xiamen 361102, China.|Department of Plant Systems Biology, Technische Universität München, Freising 85354, Germany (M.Z., C.S.).|Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden (K.L.).|Department of Cell Biology and Plant Biochemistry, Universität Regensburg, Regensburg 93047, Germany (A.F., U.Z.H.); and.|Department of Biology-Plant Biology, University of Fribourg, CH-1700 Fribourg, Switzerland (M.D.D., M.G.).
authors.forename: Martin
authors.identifier: 0000-0002-5642-2523
authors.initials: M
authors.lastname: Di Donato
authors.affiliation: School of Life Sciences, Xiamen Plant Genetics Key Laboratory (Y.G., F.Y., M.W., Y.T.), and State Key Laboratory of Cellular Stress Biology (Y.G., Y.T.), Xiamen University, Xiamen 361102, China.|Department of Plant Systems Biology, Technische Universität München, Freising 85354, Germany (M.Z., C.S.).|Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden (K.L.).|Department of Cell Biology and Plant Biochemistry, Universität Regensburg, Regensburg 93047, Germany (A.F., U.Z.H.); and.|Department of Biology-Plant Biology, University of Fribourg, CH-1700 Fribourg, Switzerland (M.D.D., M.G.).
authors.forename: Markus
authors.identifier: 0000-0002-6641-5810
authors.initials: M
authors.lastname: Geisler
authors.affiliation: School of Life Sciences, Xiamen Plant Genetics Key Laboratory (Y.G., F.Y., M.W., Y.T.), and State Key Laboratory of Cellular Stress Biology (Y.G., Y.T.), Xiamen University, Xiamen 361102, China.|Department of Plant Systems Biology, Technische Universität München, Freising 85354, Germany (M.Z., C.S.).|Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden (K.L.).|Department of Cell Biology and Plant Biochemistry, Universität Regensburg, Regensburg 93047, Germany (A.F., U.Z.H.); and.|Department of Biology-Plant Biology, University of Fribourg, CH-1700 Fribourg, Switzerland (M.D.D., M.G.).
authors.forename: Claus
authors.identifier: 0000-0002-4438-606X
authors.initials: C
authors.lastname: Schwechheimer
authors.affiliation: School of Life Sciences, Xiamen Plant Genetics Key Laboratory (Y.G., F.Y., M.W., Y.T.), and State Key Laboratory of Cellular Stress Biology (Y.G., Y.T.), Xiamen University, Xiamen 361102, China; yitao@xmu.edu.cn.|Department of Plant Systems Biology, Technische Universität München, Freising 85354, Germany (M.Z., C.S.); yitao@xmu.edu.cn.|Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden (K.L.); yitao@xmu.edu.cn.|Department of Cell Biology and Plant Biochemistry, Universität Regensburg, Regensburg 93047, Germany (A.F., U.Z.H.); and yitao@xmu.edu.cn.|Department of Biology-Plant Biology, University of Fribourg, CH-1700 Fribourg, Switzerland (M.D.D., M.G.) yitao@xmu.edu.cn.
authors.forename: Yi
authors.identifier: 0000-0002-7460-7927
authors.initials: Y
authors.lastname: Tao
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D018546:Hypocotyl / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000378:metabolism*; D009154:Mutation; D018517:Plant Roots / Q000166:cytology / Q000378:metabolism; D030821:Plants, Genetically Modified; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; C114215:ATPGP1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; C449300:PIN3 protein, Arabidopsis; C000625000:SAV4 protein, Arabidopsis