title: Linking photoreceptor excitation to changes in plant architecture.
abstract: Plants sense neighbor proximity as a decrease in the ratio of red to far-red light, which triggers a series of developmental responses. In Arabidopsis, phytochrome B (PHYB) is the major sensor of shade, but PHYB excitation has not been linked directly to a growth response. We show that the basic helix-loop-helix (bHLH) transcription factor PIF7 (phytochrome-interacting factor 7), an interactor of PHYB, accumulates in its dephosphorylated form in shade, allowing it to bind auxin biosynthetic genes and increase their expression. New auxin synthesized through a PIF7-regulated pathway is required for shade-induced growth, linking directly the perception of a light quality signal to a rapid growth response.
authors.affiliation: Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.forename: Karin
authors.initials: K
authors.lastname: Ljung
authors.forename: Ghislain
authors.initials: G
authors.lastname: Breton
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Schmitz
authors.forename: Jose
authors.initials: J
authors.lastname: Pruneda-Paz
authors.forename: Chris
authors.initials: C
authors.lastname: Cowing-Zitron
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Cole
authors.forename: Lauren J
authors.initials: LJ
authors.lastname: Ivans
authors.forename: Ullas V
authors.initials: UV
authors.lastname: Pedmale
authors.forename: Hou-Sung
authors.initials: HS
authors.lastname: Jung
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Ecker
authors.forename: Steve A
authors.initials: SA
authors.lastname: Kay
authors.forename: Joanne
authors.initials: J
authors.lastname: Chory
mesh_terms: D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism* / Q000494:pharmacology; D008027:Light; D009154:Mutation; D051939:Phytochrome B / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D007210:Indoleacetic Acids; C497952:PHYB protein, Arabidopsis; C547219:PIF7 protein, Arabidopsis; D051939:Phytochrome B