Skip to main content

Main menu

  • Home
  • Content
    • Current Issue
    • Archive
    • Preview Papers
  • About
    • Editorial Board and Staff
    • About the Journal
    • Terms & Privacy
  • More
    • Alerts
    • Contact Us
  • Submit a Manuscript
    • Instructions for Authors
    • Submit a Manuscript
  • Other Publications
    • Plant Physiology
    • The Plant Cell
    • Plant Direct
    • The Arabidopsis Book
    • Teaching Tools in Plant Biology
    • ASPB
    • Plantae

User menu

  • My alerts
  • Log in

Search

  • Advanced search
Plant Cell
  • Other Publications
    • Plant Physiology
    • The Plant Cell
    • Plant Direct
    • The Arabidopsis Book
    • Teaching Tools in Plant Biology
    • ASPB
    • Plantae
  • My alerts
  • Log in
Plant Cell

Advanced Search

  • Home
  • Content
    • Current Issue
    • Archive
    • Preview Papers
  • About
    • Editorial Board and Staff
    • About the Journal
    • Terms & Privacy
  • More
    • Alerts
    • Contact Us
  • Submit a Manuscript
    • Instructions for Authors
    • Submit a Manuscript
  • Follow PlantCell on Twitter
  • Visit PlantCell on Facebook
  • Visit Plantae
In BriefIN BRIEF
Open Access

How COR27 and COR28 Promote Hypocotyl Growth: Bind to COP1 and Suppress HY5 Activity

Hanna Hõrak
Hanna Hõrak
Institute of TechnologyUniversity of Tartu, Estonia
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • ORCID record for Hanna Hõrak

Published October 2020. DOI: https://doi.org/10.1105/tpc.20.00617

  • Article
  • Figures & Data
  • Info & Metrics
  • PDF
Loading
  • © 2020 American Society of Plant Biologists. All rights reserved.

Seedling growth and development rely on the successful integration of information from external signals, such as light and temperature, and endogenous processes, such as the rhythmic ticking of the circadian clock. Together, these signaling pathways tune hypocotyl elongation to allow seedlings to escape from the dark soil and reach the bright soil surface, followed by cotyledon expansion and suppression of hypocotyl growth during photomorphogenesis in the light.

A key signaling hub that regulates photomorphogenesis is the E3 ubiquitin ligase CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) that targets proteins for degradation via the 26S proteasome in the dark, thereby controlling the levels of light signaling proteins (Lau and Deng, 2012). Conversely, light suppresses the activity of COP1 and its partner, SUPPRESSOR OF PHYTOCHROME A1 (SPA1) via multiple regulatory mechanisms, leading to changes in downstream gene expression and appropriate developmental responses.

Light, temperature, and clock signaling pathways share several common nodes. For example, both low temperatures and light regulate the expression of COLD REGULATED GENE27 (COR27) and COR28. Likewise, COR27 and COR28 modulate the pace of the circadian clock (Li et al., 2016). In this issue of The Plant Cell, Li et al. (2020) and Zhu et al. (2020) identify a new role for COR27 and COR28 in promoting hypocotyl growth via their interaction with the COP1-SPA1 complex and regulation of downstream gene expression.

The two independent studies started with yeast two-hybrid screens to identify interaction partners for COR27 and COR28 (Li et al., 2020) or COP1 (Zhu et al., 2020). Both discovered that COR27 and COR28 interacted with COP1 and its partner, SPA1. As the COP1-SPA1 complex is involved in proteasomal degradation, both sets of authors measured COR27 protein levels in light- and dark-grown seedlings, in the wild type, and in weak cop1 mutants. COR27 accumulated in the light but was degraded in the dark, in a COP1- and 26S proteasome–dependent manner.

Analysis of the role of COR27 and COR28 during photomorphogenesis revealed their contributions to hypocotyl elongation: cor27 and cor27 cor28 mutants had shorter hypocotyls, while seedlings overexpressing COR27 or COR28 had longer hypocotyls in all light conditions, defining COR27 and COR28 as negative regulators of light signaling. As ELONGATED HYPOCOTYL5 (HY5) is a major transcriptional regulator of light responses that functions directly downstream of the COP1-SPA1 complex, both sets of authors then tested whether COR27 interacted with HY5; indeed, it did. COR27 inhibited HY5 binding to DNA, thereby suppressing its transcriptional activation activity (Zhu et al., 2020) and highlighting a mechanism by which COR27 and COR28 may affect hypocotyl elongation (see figure). COR27 may also exhibit additional functions in hypocotyl growth besides suppressing HY5 activity, based on hypocotyl length differences between the hy5 mutant and seedlings overexpressing or lacking COR27 in the hy5 background.

Figure1
  • Download figure
  • Open in new tab
  • Download powerpoint

Model for the Role of COR27 and COR28 in Hypocotyl Growth.

Light suppresses COP1 and SPA1 complex activity, preventing dark-induced degradation of COR27, COR28, and HY5. As COR27 and COR28 levels rise, they bind HY5 and suppress its transcriptional activation activity—and may interact with other transcription factors (TF)—to promote hypocotyl growth. (Adapted from Li et al. [2020], Supplemental Figure 6.)

Another master regulator of light signaling and hypocotyl elongation is the basic helix-loop-helix transcription factor PHYTOCHROME-INTERACTING FACTOR4 (PIF4). Both studies set out to test whether impairment of COR27 function affected PIF4 mRNA levels. Zhu et al. (2020) detected reduced PIF4 mRNA levels in the cor27 mutant in the afternoon, but not at other time points over the course of a 12-h-light/12-h-dark diurnal cycle. By contrast, Li et al. (2020) observed lower PIF4 expression in the cor27 cor28 mutant at night in seedlings grown in short days (8-h-light/16-h-dark cycle), but did not test other time points. Addressing the role of photoperiod and light intensity may help clarify the interactions between COR27, COR28, and PIF4 expression.

The studies by Li et al. (2020) and Zhu et al. (2020) present strong evidence for a COP1-dependent role of COR27 and COR28 in the promotion of hypocotyl growth. How this effect is executed through downstream targets, such as HY5 and potentially other transcription factors, will be the next pieces to place in the puzzle of temperature, light, and circadian clock signaling.

Footnotes

  • www.plantcell.org/cgi/doi/10.1105/tpc.20.00617

  • ↵[OPEN] Articles can be viewed without a subscription.

References

  1. ↵
    1. Lau, O.S.,
    2. Deng, X.W.
    (2012). The photomorphogenic repressors COP1 and DET1: 20 years later. Trends Plant Sci. 17: 584–593.
    OpenUrlCrossRefPubMed
  2. ↵
    1. Li, X.,
    2. Ma, D.,
    3. Lu, S.X.,
    4. Hu, X.,
    5. Huang, R.,
    6. Liang, T.,
    7. Xu, T.,
    8. Tobin, E.M.,
    9. Liu, H.
    (2016). Blue light- and low temperature-regulated COR27 and COR28 play roles in the Arabidopsis circadian clock. Plant Cell 28: 2755–2769.
    OpenUrlAbstract/FREE Full Text
  3. ↵
    1. Li, X.,
    2. Liu, C.,
    3. Zhao, Z.,
    4. Ma, D.,
    5. Zhang, J.,
    6. Yang, Y.,
    7. Liu, Y.,
    8. Liu, H.
    (2020). COR27 and COR28 are novel regulators of the COP1–HY5 regulatory hub and photomorphogenesis in Arabidopsis. Plant Cell 32: 3139–3154.
    OpenUrlAbstract/FREE Full Text
  4. ↵
    1. Zhu, W.,
    2. Zhou, H.,
    3. Lin, F.,
    4. Zhao, X.,
    5. Jiang, Y.,
    6. Xu, D.,
    7. Deng, X.W
    (2020). COLD-REGULATED GENE27 integrates signals from light and the circadian clock to promote hypocotyl growth in Arabidopsis. Plant Cell 32: 3155–3169.
    OpenUrlAbstract/FREE Full Text
PreviousNext
Back to top

Table of Contents

Print
Download PDF
Email Article

Thank you for your interest in spreading the word on Plant Cell.

NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.

Enter multiple addresses on separate lines or separate them with commas.
How COR27 and COR28 Promote Hypocotyl Growth: Bind to COP1 and Suppress HY5 Activity
(Your Name) has sent you a message from Plant Cell
(Your Name) thought you would like to see the Plant Cell web site.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Citation Tools
How COR27 and COR28 Promote Hypocotyl Growth: Bind to COP1 and Suppress HY5 Activity
Hanna Hõrak
The Plant Cell Oct 2020, 32 (10) 3045-3046; DOI: 10.1105/tpc.20.00617

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero
Request Permissions
Share
How COR27 and COR28 Promote Hypocotyl Growth: Bind to COP1 and Suppress HY5 Activity
Hanna Hõrak
The Plant Cell Oct 2020, 32 (10) 3045-3046; DOI: 10.1105/tpc.20.00617
del.icio.us logo Digg logo Reddit logo Twitter logo CiteULike logo Facebook logo Google logo Mendeley logo
  • Tweet Widget
  • Facebook Like
  • Google Plus One

Jump to section

  • Article
    • Footnotes
    • References
  • Figures & Data
  • Info & Metrics
  • PDF

In this issue

The Plant Cell: 32 (10)
The Plant Cell
Vol. 32, Issue 10
Oct 2020
  • Table of Contents
  • Table of Contents (PDF)
  • Cover (PDF)
  • About the Cover
  • Index by author
View this article with LENS

More in this TOC Section

  • The Lure of Lignin: Deciphering High-value Lignin Formation in Seed Coats
  • Got Rosettes? Phenotype Them Fast, Accurately, and Easily with ARADEEPOPSIS!
  • Ripe for the Picking: Finding the Gene Behind Variation in Strawberry Fruit Color
Show more IN BRIEF

Similar Articles

Our Content

  • Home
  • Current Issue
  • Plant Cell Preview
  • Archive
  • Teaching Tools in Plant Biology
  • Plant Physiology
  • Plant Direct
  • Plantae
  • ASPB

For Authors

  • Instructions
  • Submit a Manuscript
  • Editorial Board and Staff
  • Policies
  • Recognizing our Authors

For Reviewers

  • Instructions
  • Peer Review Reports
  • Journal Miles
  • Transfer of reviews to Plant Direct
  • Policies

Other Services

  • Permissions
  • Librarian resources
  • Advertise in our journals
  • Alerts
  • RSS Feeds
  • Contact Us

Copyright © 2021 by The American Society of Plant Biologists

Powered by HighWire