scholarly journals FAR-RED ELONGATED HYPOCOTYL1 and FHY1-LIKE Associate with the Arabidopsis Transcription Factors LAF1 and HFR1 to Transmit Phytochrome A Signals for Inhibition of Hypocotyl Elongation

2009 ◽  
Vol 21 (5) ◽  
pp. 1341-1359 ◽  
Author(s):  
Seong Wook Yang ◽  
In-Cheol Jang ◽  
Rossana Henriques ◽  
Nam-Hai Chua
Keyword(s):  
Transcription Factors ◽  
Hypocotyl Elongation ◽  
Phytochrome A

scholarly journals Guard cells control hypocotyl elongation through HXK1, HY5, and PIF4

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Gilor Kelly ◽  
Danja Brandsma ◽  
Aiman Egbaria ◽  
Ofer Stein ◽  
Adi Doron-Faigenboim ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Blue Light ◽  
Opposite Effect ◽  
Red Light ◽  
Guard Cells ◽  
Cell Types ◽  
Hypocotyl Elongation ◽  
Sugar Production ◽  
Effect Of Light

AbstractThe hypocotyls of germinating seedlings elongate in a search for light to enable autotrophic sugar production. Upon exposure to light, photoreceptors that are activated by blue and red light halt elongation by preventing the degradation of the hypocotyl-elongation inhibitor HY5 and by inhibiting the activity of the elongation-promoting transcription factors PIFs. The question of how sugar affects hypocotyl elongation and which cell types stimulate and stop that elongation remains unresolved. We found that overexpression of a sugar sensor, Arabidopsis hexokinase 1 (HXK1), in guard cells promotes hypocotyl elongation under white and blue light through PIF4. Furthermore, expression of PIF4 in guard cells is sufficient to promote hypocotyl elongation in the light, while expression of HY5 in guard cells is sufficient to inhibit the elongation of the hy5 mutant and the elongation stimulated by HXK1. HY5 exits the guard cells and inhibits hypocotyl elongation, but is degraded in the dark. We also show that the inhibition of hypocotyl elongation by guard cells’ HY5 involves auto-activation of HY5 expression in other tissues. It appears that guard cells are capable of coordinating hypocotyl elongation and that sugar and HXK1 have the opposite effect of light on hypocotyl elongation, converging at PIF4.

scholarly journals Dawn and photoperiod sensing by phytochrome A

2018 ◽  
Vol 115 (41) ◽  
pp. 10523-10528 ◽  
Author(s):  
Daniel D. Seaton ◽  
Gabriela Toledo-Ortiz ◽  
Ashwin Ganpudi ◽  
Akane Kubota ◽  
Takato Imaizumi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Functional Genomic ◽  
Anthocyanin Accumulation ◽  
Sensitive Detector ◽  
Phytochrome A ◽  
Direct Control ◽  
Physiological Processes ◽  
Complex Regulation

In plants, light receptors play a pivotal role in photoperiod sensing, enabling them to track seasonal progression. Photoperiod sensing arises from an interaction between the plant’s endogenous circadian oscillator and external light cues. Here, we characterize the role of phytochrome A (phyA) in photoperiod sensing. Our metaanalysis of functional genomic datasets identified phyA as a principal regulator of morning-activated genes, specifically in short photoperiods. We demonstrate that PHYA expression is under the direct control of the PHYTOCHROME INTERACTING FACTOR transcription factors, PIF4 and PIF5. As a result, phyA protein accumulates during the night, especially in short photoperiods. At dawn, phyA activation by light results in a burst of gene expression, with consequences for physiological processes such as anthocyanin accumulation. The combination of complex regulation of PHYA transcript and the unique molecular properties of phyA protein make this pathway a sensitive detector of both dawn and photoperiod.

scholarly journals Adaptation to plant shade relies on rebalancing the transcriptional activity of the PIF-HFR1 regulatory module

2020 ◽  
Author(s):  
Sandi Paulišić ◽  
Christiane Then ◽  
Benjamin Alary ◽  
Fabien Nogue ◽  
Miltos Tsiantis ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Shade Tolerance ◽  
Transcriptional Activity ◽  
Hypocotyl Elongation ◽  
Phytochrome A ◽  
Warm Temperature ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Regulatory Module ◽  
Induced Genes

ABSTRACTShade 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, contributing to enhance its biological activity. The enhanced HFR1 activity is accompanied by an attenuated PHYTOCHROME INTERACTING FACTOR (PIF) activity in C. hirsuta. As a result, the PIF-HFR1 module is imbalanced, 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.

scholarly journals Shade-induced WRKY transcription factors restrict root growth during the shade avoidance response

2021 ◽  
Author(s):  
Daniele Rosado ◽  
Amanda Ackermann ◽  
Olya Spassibojko ◽  
Magdalena Rossi ◽  
Ullas V Pedmale
Keyword(s):  
Transcription Factors ◽  
Root Growth ◽  
Avoidance Response ◽  
Primary Root ◽  
Hypocotyl Elongation ◽  
Shade Avoidance ◽  
Wrky Transcription Factors ◽  
Tomato Seedlings ◽  
Induced Genes ◽  
Growth Adaptation

Shade-intolerant plants rapidly elongate their stems, branches, and leaf stalks to compete with their neighboring vegetation to maximize sunlight capture for photosynthesis. This rapid growth adaptation, known as the shade avoidance response (SAR), comes at a cost; reduced biomass, crop yield, and root growth. Significant progress has been made on the mechanistic understanding of hypocotyl elongation during SAR; however, the molecular account of how root growth is repressed is not well understood. Here, we explore the mechanisms by which low red:far-red induced SAR restrict the primary and lateral root (LR) growth. By analyzing whole-genome transcriptome, we identified a core set of shade-induced genes in the roots of Arabidopsis and tomato seedlings grown in the shade. Abiotic and biotic stressors also induce many of these shade-induced genes and are predominantly regulated by the WRKY transcription factors. Correspondingly, a majority of the WRKYs were also among the shade-induced genes. Functional analysis using transgenics of these shade-induced WRKYs revealed their role is essentially to restrict primary root and LR growth in the shade, and captivatingly, they did not affect hypocotyl elongation. Similarly, we also show that ethylene hormone signaling is necessary to limit root growth in the shade. Our study proposes that during SAR, shade-induced WRKY26, 45, and 75, and ethylene reprogram gene expression in the root to restrict its growth and development. The reduced growth of root organs helps the plant divert its critical resources to the elongating organs in the shoot to ensure competitiveness under limiting photosynthetic radiation

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