title: The time of day effects of warm temperature on flowering time involve PIF4 and PIF5.
abstract: Warm temperature promotes flowering in Arabidopsis thaliana and this response involves multiple signalling pathways. To understand the temporal dynamics of temperature perception, tests were carried out to determine if there was a daily window of enhanced sensitivity to warm temperature (28 °C). Warm temperature applied during daytime, night-time, or continuously elicited earlier flowering, but the effects of each treatment were unequal. Plants exposed to warm night (WN) conditions flowered nearly as early as those in constant warm (CW) conditions, while treatment with warm days (WD) caused later flowering than either WN or CW. Flowering in each condition relied to varying degrees on the activity of CO , FT , PIF4 , and PIF5 , as well as the action of unknown genes. The combination of signalling pathways involved in flowering depended on the time of the temperature cue. WN treatments caused a significant advance in the rhythmic expression waveform of CO, which correlated with pronounced up-regulation of FT expression, while WD caused limited changes in CO expression and no stimulation of FT expression. WN- and WD-induced flowering was partially CO independent and, unexpectedly, dependent on PIF4 and PIF5 . pif4-2, pif5-3, and pif4-2 pif5-3 mutants had delayed flowering under all three warm conditions. The double mutant was also late flowering in control conditions. In addition, WN conditions alone imposed selective changes to PIF4 and PIF5 expression. Thus, the PIF4 and PIF5 transcription factors promote flowering by at least two means: inducing FT expression in WN and acting outside of FT by an unknown mechanism in WD.
authors.affiliation: Department of Plant & Microbial Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Bryan C
authors.initials: BC
authors.lastname: Thines
authors.forename: Youngwon
authors.initials: Y
authors.lastname: Youn
authors.forename: Maritza I
authors.initials: MI
authors.lastname: Duarte
authors.forename: Frank G
authors.initials: FG
authors.lastname: Harmon
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000502:physiology / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism; D057906:Circadian Clocks; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000502:physiology / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant; D018546:Hypocotyl / Q000235:genetics / Q000254:growth & development / Q000502:physiology / Q000528:radiation effects; D008027:Light; D009154:Mutation; D017440:Photoperiod; D030821:Plants, Genetically Modified; D015398:Signal Transduction; D013696:Temperature; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D014157:Transcription Factors; C092776:CONSTANS protein, Arabidopsis; C418905:FT protein, Arabidopsis; C459466:PIF4 protein, Arabidopsis; C497729:PIF5 protein, Arabidopsis
keywords: CONSTANS; Circadian clock; FLOWERING LOCUS T; PHYTOCHROME INTERACTING FACTOR; PIF4; PIF5; flowering; temperature response.