title: The epidermis coordinates auxin-induced stem growth in response to shade.
abstract: Growth of a complex multicellular organism requires coordinated changes in diverse cell types. These cellular changes generate organs of the correct size, shape, and functionality. In plants, the growth hormone auxin induces stem elongation in response to shade; however, which cell types of the stem perceive the auxin signal and contribute to organ growth is poorly understood. Here, we blocked the transcriptional response to auxin within specific tissues to show that auxin signaling is required in many cell types for correct hypocotyl growth in shade, with a key role for the epidermis. Combining genetic manipulations in Arabidopsis thaliana with transcriptional profiling of the hypocotyl epidermis from Brassica rapa, we show that auxin acts in the epidermis in part by inducing activity of the locally acting, growth-promoting brassinosteroid pathway. Our findings clarify cell-specific auxin function in the hypocotyl and highlight the complexity of cell type interactions within a growing organ.
authors.affiliation: Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA;
authors.forename: Carl
authors.initials: C
authors.lastname: Procko
authors.affiliation: Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA;
authors.forename: Yogev
authors.initials: Y
authors.lastname: Burko
authors.affiliation: Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA;
authors.forename: Yvon
authors.identifier: 0000-0003-4923-883X
authors.initials: Y
authors.lastname: Jaillais
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: Department of Molecular, Cell, and Developmental Biology, University of California at Los Angeles, Los Angeles, California 90095, USA;
authors.forename: Jeff A
authors.initials: JA
authors.lastname: Long
authors.affiliation: Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA; Howard Hughes Medical Institute, 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; D029681:Arabidopsis Proteins / Q000235:genetics; D029741:Brassica rapa / Q000235:genetics / Q000254:growth & development; D060406:Brassinosteroids / Q000378:metabolism / Q000494:pharmacology; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D018546:Hypocotyl / Q000166:cytology / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects; D007210:Indoleacetic Acids / Q000378:metabolism*; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics; D019441:Plant Epidermis / Q000378:metabolism* / Q000528:radiation effects; D015398:Signal Transduction; D013472:Sunlight; D014157:Transcription Factors
chemical_list: C110728:AXR3 protein, Arabidopsis; D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D007210:Indoleacetic Acids; D009687:Nuclear Proteins; D014157:Transcription Factors
keywords: auxin; brassinosteroid; epidermis; shade avoidance; stem growth