title: Functional profiling identifies genes involved in organ-specific branches of the PIF3 regulatory network in Arabidopsis.
abstract: The phytochrome (phy)-interacting basic helix-loop-helix transcription factors (PIFs) constitutively sustain the etiolated state of dark-germinated seedlings by actively repressing deetiolation in darkness. This action is rapidly reversed upon light exposure by phy-induced proteolytic degradation of the PIFs. Here, we combined a microarray-based approach with a functional profiling strategy and identified four PIF3-regulated genes misexpressed in the dark (MIDAs) that are novel regulators of seedling deetiolation. We provide evidence that each one of these four MIDA genes regulates a specific facet of etiolation (hook maintenance, cotyledon appression, or hypocotyl elongation), indicating that there is branching in the signaling that PIF3 relays. Furthermore, combining inferred MIDA gene function from mutant analyses with their expression profiles in response to light-induced degradation of PIF3 provides evidence consistent with a model where the action of the PIF3/MIDA regulatory network enables an initial fast response to the light and subsequently prevents an overresponse to the initial light trigger, thus optimizing the seedling deetiolation process. Collectively, the data suggest that at least part of the phy/PIF system acts through these four MIDAs to initiate and optimize seedling deetiolation, and that this mechanism might allow the implementation of spatial (i.e., organ-specific) and temporal responses during the photomorphogenic program.
authors: Departament de Genètica Molecular, Center for Research in Agricultural Genomics, Centro Superior de Investigaciones Científicas-Institut de Recerca i Tecnologia Agroalimentàries-Universitat Autònoma de Barcelona-Universitat de Barcelona, 08193 Barcelona, Spain.
authors: Maria
authors: M
authors: Sentandreu
authors: Guiomar
authors: G
authors: Martín
authors: Nahuel
authors: N
authors: González-Schain
authors: Pablo
authors: P
authors: Leivar
authors: Judit
authors: J
authors: Soy
authors: James M
authors: JM
authors: Tepperman
authors: Peter H
authors: PH
authors: Quail
authors: Elena
authors: E
authors: Monte
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D018548:Cotyledon / Q000502:physiology; D003624:Darkness; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D018546:Hypocotyl / Q000502:physiology; D008027:Light; D009154:Mutation; D009928:Organ Specificity; D036226:Seedlings / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; C116162:PIF3 protein, Arabidopsis