title: High temperature-mediated adaptations in plant architecture require the bHLH transcription factor PIF4.
abstract: Exposure of Arabidopsis plants to high temperature (28 degrees C) results in a dramatic change in plant development. Responses to high temperature include rapid extension of plant axes, leaf hyponasty, and early flowering. These phenotypes parallel plant responses to the threat of vegetational shade and have been shown to involve the hormone auxin. In this work, we demonstrate that high temperature-induced architectural adaptations are mediated through the bHLH transcriptional regulator PHYTOCHROME INTERACTING FACTOR 4 (PIF4). Roles for PIF4 have previously been established in both light and gibberellin (GA) signaling, through interactions with phytochromes and DELLA proteins, respectively. Mutants deficient in PIF4 do not display elongation responses or leaf hyponasty upon transfer to high temperature. High temperature-mediated induction of the auxin-responsive gene IAA29 is also abolished in these plants. An early flowering response to high temperature is maintained in pif4 mutants, suggesting that architectural and flowering responses operate via separate signaling pathways. The role of PIF4 in temperature signaling does not, however, appear to operate through interaction with either phytochrome or DELLA proteins, suggesting the existence of a novel regulatory mechanism. We conclude that PIF4 is an important component of plant high temperature signaling and integrates multiple environmental cues during plant development.
authors.affiliation: Department of Biology, University of Leicester, University Road, Leicester LE1 7RH, UK.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Koini
authors.forename: Liz
authors.initials: L
authors.lastname: Alvey
authors.forename: Trudie
authors.initials: T
authors.lastname: Allen
authors.forename: Ceinwen A
authors.initials: CA
authors.lastname: Tilley
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Harberd
authors.forename: Garry C
authors.initials: GC
authors.lastname: Whitelam
authors.forename: Keara A
authors.initials: KA
authors.lastname: Franklin
mesh_terms: D000220:Adaptation, Biological; D017360:Arabidopsis / Q000033:anatomy & histology / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018257:Helix-Loop-Helix Motifs; D006358:Hot Temperature; D010834:Phytochrome / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D010834:Phytochrome; C459466:PIF4 protein, Arabidopsis