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Mol. Cells 2010; 29(5): 449-456

Published online May 31, 2010

https://doi.org/10.1007/s10059-010-0055-6

© The Korean Society for Molecular and Cellular Biology

A Transcriptional Feedback Loop Modulating Signaling Crosstalks between Auxin and Brassinosteroid in Arabidopsis

Jae-Hoon Jung1, Minsun Lee1, and Chung-Mo Park1,2,*

1Department of Chemistry, Seoul National University, Seoul 151-742, Korea, 2Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-742, Korea

Correspondence to : *Correspondence: cmpark@snu.ac.kr

Received: August 7, 2010; Revised: January 9, 2010; Accepted: January 20, 2010

Abstract

Auxin and brassinosteroid (BR) play essential roles in diverse aspects of growth and developmental processes in plants mainly through coordinate regulation of cell division, elongation, and differentiation. Consistent with the overlapped roles, accumulating evidence indicates that the two growth hormones act in a synergistic as well as in an interdependent manner in many cases, although the underlying molecular mechanisms are not fully understood. Here, we demonstrate that auxin and BR signaling pathways are interconnected at the transcriptional level via a negative feedback loop. An Arabidopsis activating tagging mutant dlf-1D exhibited dwarfed growth with small, dark-green leaves and reduced fertility. Hormone feeding assays revealed that the mutant phenotype is caused by the reduction of endogenous BR level. Consistent with this, a gene encoding the CYP72C1 enzyme that catabolizes BR was up-regulated. Notably, the transcript level of the ARF8 transcription factor gene, which modulates the expression of auxin-responsive genes, was significantly elevated in the mutant. In addition, the ARF8 gene expression was significantly reduced by BR but induced by brassinazole, a BR biosynthetic inhibitor. On the other hand, two BR catabolic pathway genes, DLF (CYP72C1) and BAS1, were induced by auxin. Our observations indicate that at least part of auxin and BR signaling pathways are unified through a transcriptional feedback control of the DLF and ARF8 genes.

Keywords activation tagging mutagenesis, Arabidopsis, auxin, brassinosteroid, signal transduction

Article

Research Article

Mol. Cells 2010; 29(5): 449-456

Published online May 31, 2010 https://doi.org/10.1007/s10059-010-0055-6

Copyright © The Korean Society for Molecular and Cellular Biology.

A Transcriptional Feedback Loop Modulating Signaling Crosstalks between Auxin and Brassinosteroid in Arabidopsis

Jae-Hoon Jung1, Minsun Lee1, and Chung-Mo Park1,2,*

1Department of Chemistry, Seoul National University, Seoul 151-742, Korea, 2Plant Genomics and Breeding Institute, Seoul National University, Seoul 151-742, Korea

Correspondence to:*Correspondence: cmpark@snu.ac.kr

Received: August 7, 2010; Revised: January 9, 2010; Accepted: January 20, 2010

Abstract

Auxin and brassinosteroid (BR) play essential roles in diverse aspects of growth and developmental processes in plants mainly through coordinate regulation of cell division, elongation, and differentiation. Consistent with the overlapped roles, accumulating evidence indicates that the two growth hormones act in a synergistic as well as in an interdependent manner in many cases, although the underlying molecular mechanisms are not fully understood. Here, we demonstrate that auxin and BR signaling pathways are interconnected at the transcriptional level via a negative feedback loop. An Arabidopsis activating tagging mutant dlf-1D exhibited dwarfed growth with small, dark-green leaves and reduced fertility. Hormone feeding assays revealed that the mutant phenotype is caused by the reduction of endogenous BR level. Consistent with this, a gene encoding the CYP72C1 enzyme that catabolizes BR was up-regulated. Notably, the transcript level of the ARF8 transcription factor gene, which modulates the expression of auxin-responsive genes, was significantly elevated in the mutant. In addition, the ARF8 gene expression was significantly reduced by BR but induced by brassinazole, a BR biosynthetic inhibitor. On the other hand, two BR catabolic pathway genes, DLF (CYP72C1) and BAS1, were induced by auxin. Our observations indicate that at least part of auxin and BR signaling pathways are unified through a transcriptional feedback control of the DLF and ARF8 genes.

Keywords: activation tagging mutagenesis, Arabidopsis, auxin, brassinosteroid, signal transduction

Mol. Cells
Sep 30, 2022 Vol.45 No.9, pp. 603~672
COVER PICTURE
The Target of Rapamycin Complex (TORC) is a central regulatory hub in eukaryotes, which is well conserved in diverse plant species, including tomato (Solanum lycopersicum). Inhibition of TORC genes (SlTOR, SlLST8, and SlRAPTOR) by VIGS (virus-induced gene silencing) results in early fruit ripening in tomato. The red/ orange tomatoes are early-ripened TORC-silenced fruits, while the green tomato is a control fruit. Top, left, control fruit (TRV2-myc); top, right, TRV2-SlLST8; bottom, left, TRV2-SlTOR; bottom, right, TRV2-SlRAPTOR(Choi et al., pp. 660-672).

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