Adjustment of the PIF7-HFR1 transcriptional module activity controls plant shade adaptation

EMBO J. 2021 Jan 4;40(1):e104273. doi: 10.15252/embj.2019104273. Epub 2020 Dec 2.


Shade caused by the proximity of neighboring vegetation triggers a set of acclimation responses to either avoid or tolerate shade. Comparative analyses between the shade-avoider Arabidopsis thaliana and the shade-tolerant Cardamine hirsuta revealed a role for the atypical basic-helix-loop-helix LONG HYPOCOTYL IN FR 1 (HFR1) in maintaining the shade tolerance in C. hirsuta, inhibiting hypocotyl elongation in shade and constraining expression profile of shade-induced genes. We showed that C. hirsuta HFR1 protein is more stable than its A. thaliana counterpart, likely due to its lower binding affinity to CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), contributing to enhance its biological activity. The enhanced HFR1 total activity is accompanied by an attenuated PHYTOCHROME INTERACTING FACTOR (PIF) activity in C. hirsuta. As a result, the PIF-HFR1 module is differently balanced, causing a reduced PIF activity and attenuating other PIF-mediated responses such as warm temperature-induced hypocotyl elongation (thermomorphogenesis) and dark-induced senescence. By this mechanism and that of the already-known of phytochrome A photoreceptor, plants might ensure to properly adapt and thrive in habitats with disparate light amounts.

Keywords: Cardamine hirsuta; HFR1; PIFs; shade avoidance; shade tolerance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acclimatization / genetics*
  • Arabidopsis / genetics*
  • Arabidopsis Proteins / genetics*
  • Base Sequence
  • Basic Helix-Loop-Helix Transcription Factors / genetics
  • DNA-Binding Proteins / genetics*
  • Gene Expression Regulation, Plant / genetics*
  • Hypocotyl / genetics
  • Phytochrome / genetics
  • Transcription, Genetic / genetics*


  • Arabidopsis Proteins
  • Basic Helix-Loop-Helix Transcription Factors
  • DNA-Binding Proteins
  • HFR1 protein, Arabidopsis
  • PIF7 protein, Arabidopsis
  • Phytochrome