title: Phytochrome interacting factors 4 and 5 control seedling growth in changing light conditions by directly controlling auxin signaling.
abstract: Plant growth is strongly influenced by the presence of neighbors that compete for light resources. In response to vegetational shading shade-intolerant plants such as Arabidopsis display a suite of developmental responses known as the shade-avoidance syndrome (SAS). The phytochrome B (phyB) photoreceptor is the major light sensor to mediate this adaptive response. Control of the SAS occurs in part with phyB, which controls protein abundance of phytochrome-interacting factors 4 and 5 (PIF4 and PIF5) directly. The shade-avoidance response also requires rapid biosynthesis of auxin and its transport to promote elongation growth. The identification of genome-wide PIF5-binding sites during shade avoidance revealed that this bHLH transcription factor regulates the expression of a subset of previously identified SAS genes. Moreover our study suggests that PIF4 and PIF5 regulate elongation growth by controlling directly the expression of genes that code for auxin biosynthesis and auxin signaling components.
authors.affiliation: Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Patricia
authors.initials: P
authors.lastname: Hornitschek
authors.forename: Markus V
authors.initials: MV
authors.lastname: Kohnen
authors.forename: Séverine
authors.initials: S
authors.lastname: Lorrain
authors.forename: Jacques
authors.initials: J
authors.lastname: Rougemont
authors.forename: Karin
authors.initials: K
authors.lastname: Ljung
authors.forename: Irene
authors.initials: I
authors.lastname: López-Vidriero
authors.forename: José M
authors.initials: JM
authors.lastname: Franco-Zorrilla
authors.forename: Roberto
authors.initials: R
authors.lastname: Solano
authors.forename: Martine
authors.initials: M
authors.lastname: Trevisan
authors.forename: Sylvain
authors.initials: S
authors.lastname: Pradervand
authors.forename: Ioannis
authors.initials: I
authors.lastname: Xenarios
authors.forename: Christian
authors.initials: C
authors.lastname: Fankhauser
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D007210:Indoleacetic Acids / Q000378:metabolism*; D008027:Light; D036226:Seedlings / Q000254:growth & development / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D007210:Indoleacetic Acids; C459466:PIF4 protein, Arabidopsis; C497729:PIF5 protein, Arabidopsis