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Updated: May 14, 2026

Investigating Tissue- and Organ-specific Phytochrome Responses using FACS-assisted Cell-type Specific Expression Profiling in Arabidopsis thaliana
Published on: May 29, 2010
TCP21 negatively regulates photomorphogenesis by integrating phyB- and HY5-mediated signaling pathways in Arabidopsis
Mengdi Zhang1,2, Yueqin Heng3, Siqi Yan1
1Shenzhen Key Laboratory of Plant Genetic Engineering and Molecular Design, Department of Biology, School of Life Sciences, Institute of Plant and Food Science, Southern University of Science and Technology, Shenzhen, 518055, China.
Abstract:
The phytochrome B (phyB)-transcription factor signaling module plays a critical role in regulating photomorphogenesis. In this study, TCP21, a member of the Class I TCP transcription factor family, was identified as a direct interacting partner of phyB. TCP21 negatively regulates photomorphogenesis through downregulating HY5 expression and repressing the transcriptional activity of HY5. Moreover, phyB physically interacts with TCP21 and inhibits its transcriptional activity. Notably, phyB outcompetes HY5 for binding to TCP21, thereby attenuating the interaction between TCP21 and HY5 and alleviating TCP21-mediated repression of HY5 DNA-binding ability. Collectively, these findings establish TCP21 as a key component within the phyB-HY5 signaling module, contributing to plant adaptation to dynamic light environments.
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