FAR-RED INSENSITIVE219 Modulates CONSTITUTIVE PHOTOMORPHOGENIC1 Activity via Physical Interaction to Regulate Hypocotyl Elongation in Arabidopsis

Jhy-Gong Wang,Chih-Hao Chen,Hsu-Liang Hsieh,Ching-Te Chien

doi:10.1104/pp.111.177667

Jhy-Gong Wang, Chih-Hao Chen + Show 2 more

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https://doi.org/10.1104/pp.111.177667

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Journal: Plant Physiology	Publication Date: Apr 27, 2011
Citations: 35	License type: CC BY 4.0

Affiliation: Taiwan Forestry Research Institute

Abstract

FAR-RED INSENSITIVE219 (FIN219) in Arabidopsis (Arabidopsis thaliana) is involved in phytochrome A-mediated far-red (FR) light signaling. Previous genetic studies revealed that FIN219 acts as an extragenic suppressor of CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1). However, the molecular mechanism underlying the suppression of COP1 remains unknown. Here, we used a transgenic approach to study the regulation of COP1 by FIN219. Transgenic seedlings containing ectopic expression of the FIN219 amino (N)-terminal domain in wild-type Columbia (named NCox for the expression of the N-terminal coiled-coil domain and NTox for the N-terminal 300-amino acid region) exhibited a dominant-negative long-hypocotyl phenotype under FR light, reflected as reduced photomorphogenic responses and altered levels of COP1 and ELONGATED HYPOCOTYL5 (HY5). Yeast two-hybrid, pull-down, and bimolecular fluorescence complementation assays revealed that FIN219 could interact with the WD-40 domain of COP1 and with its N-terminal coiled-coil domain through its carboxyl-terminal domain. Further in vivo coimmunoprecipitation study confirms that FIN219 interacts with COP1 under continuous FR light. Studies of the double mutant fin219-2/cop1-6 indicated that HY5 stability requires FIN219 under darkness and FR light. Moreover, FIN219 levels positively regulated by phytochrome A can modulate the subcellular location of COP1 and are differentially regulated by various fluence rates of FR light. We conclude that the dominant-negative long-hypocotyl phenotype conferred by NCox and NTox in a wild-type background was caused by the misregulation of COP1 binding with the carboxyl terminus of FIN219. Our data provide a critical mechanism controlling the key repressor COP1 in response to FR light.

Highlights

FAR-RED INSENSITIVE219 (FIN219) in Arabidopsis (Arabidopsis thaliana) is involved in phytochrome A-mediated far-red (FR) light signaling
We demonstrate that FIN219/JASMONATE RESISTANT1 (JAR1) negatively regulates CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) levels through physical interaction under continuous farred (cFR) light and can modulate the subcellular location of COP1 even in the dark
Our data reveal a new finding that FIN219/JAR1 functions as a positive regulator of phytochrome A (phyA)-mediated FR light signaling by controlling the levels of COP1 and HY5 to modulate photomorphogenic development in Arabidopsis

Summary

Introduction

FAR-RED INSENSITIVE219 (FIN219) in Arabidopsis (Arabidopsis thaliana) is involved in phytochrome A-mediated far-red (FR) light signaling. Genetic and molecular studies of Arabidopsis (Arabidopsis thaliana) have identified numerous light-signaling intermediates, including positive and negative regulators (Ni et al, 1998; Soh et al, 1998, 2000; Hoecker et al, 1999; Hudson et al, 1999; Bolle et al, 2000; Fairchild et al, 2000; Fankhauser and Chory, 2000; Hsieh et al, 2000; Ballesteros et al, 2001; Desnos et al, 2001; Dieterle et al, 2001; Zeidler et al, 2001; Wang and Deng, 2002). HY5, a basic Leu zipper transcription factor, functions as a positive regulator downstream of COP1 and is regulated by multiple photoreceptors to control various light responses (Osterlund et al, 2000a), including gravitropism, wavy root growth, and hypocotyl elongation (Oyama et al, 1997), as well as the integration of light signals and various phytohormones to regulate germination and seedling development (Vandenbussche et al, 2007; Alabadı et al, 2008; Chen et al, 2008). HY5 plays a key role in light signaling

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