Non-transcriptional regulatory activity of SMAX1 and SMXL2 mediates karrikin-regulated seedling response to red light in Arabidopsis
- PMID: 38807366
- DOI: 10.1016/j.molp.2024.05.007
Non-transcriptional regulatory activity of SMAX1 and SMXL2 mediates karrikin-regulated seedling response to red light in Arabidopsis
Abstract
Karrikins and strigolactones govern plant development and environmental responses through closely related signaling pathways. The transcriptional repressor proteins SUPPRESSOR OF MAX2 1 (SMAX1), SMAX1-like2 (SMXL2), and D53-like SMXLs mediate karrikin and strigolactone signaling by directly binding downstream genes or by inhibiting the activities of transcription factors. In this study, we characterized the non-transcriptional regulatory activities of SMXL proteins in Arabidopsis. We discovered that SMAX1 and SMXL2 with mutations in their ethylene-response factor-associated amphiphilic repression (EAR) motif had undetectable or weak transcriptional repression activities but still partially rescued the hypocotyl elongation defects and fully reversed the cotyledon epinasty defects of the smax1 smxl2 mutant. SMAX1 and SMXL2 directly interact with PHYTOCHROME INTERACTION FACTOR 4 (PIF4) and PIF5 to enhance their protein stability by interacting with phytochrome B (phyB) and suppressing the association of phyB with PIF4 and PIF5. The karrikin-responsive genes were then identified by treatment with GR24ent-5DS, a GR24 analog showing karrikin activity. Interestingly, INDOLE-3-ACETIC ACID INDUCIBLE 29 (IAA29) expression was repressed by GR24ent-5DS treatment in a PIF4- and PIF5-dependent and EAR-independent manner, whereas KARRIKIN UPREGULATED F-BOX 1 (KUF1) expression was induced in a PIF4- and PIF5-independent and EAR-dependent manner. Furthermore, the non-transcriptional regulatory activity of SMAX1, which is independent of the EAR motif, had a global effect on gene expression. Taken together, these results indicate that non-transcriptional regulatory activities of SMAX1 and SMXL2 mediate karrikin-regulated seedling response to red light.
Keywords: PIF4 and PIF5; SMAX1 and SMXL2; gene expression; karrikin signaling; non-transcriptional repression activity; red light.
Copyright © 2024 The Author. Published by Elsevier Inc. All rights reserved.
Conflict of interest statement
Declaration of interests The authors declare no competing financial interests.
Similar articles
-
Strigolactone and Karrikin Signaling Pathways Elicit Ubiquitination and Proteolysis of SMXL2 to Regulate Hypocotyl Elongation in Arabidopsis.Plant Cell. 2020 Jul;32(7):2251-2270. doi: 10.1105/tpc.20.00140. Epub 2020 Apr 30. Plant Cell. 2020. PMID: 32358074 Free PMC article.
-
Functional redundancy in the control of seedling growth by the karrikin signaling pathway.Planta. 2016 Jun;243(6):1397-406. doi: 10.1007/s00425-015-2458-2. Epub 2016 Jan 11. Planta. 2016. PMID: 26754282 Free PMC article.
-
Karrikins control seedling photomorphogenesis and anthocyanin biosynthesis through a HY5-BBX transcriptional module.Plant J. 2021 Sep;107(5):1346-1362. doi: 10.1111/tpj.15383. Epub 2021 Jul 19. Plant J. 2021. PMID: 34160854
-
The karrikin response system of Arabidopsis.Plant J. 2014 Aug;79(4):623-31. doi: 10.1111/tpj.12430. Epub 2014 Feb 24. Plant J. 2014. PMID: 24433542 Review.
-
Signalling and responses to strigolactones and karrikins.Curr Opin Plant Biol. 2014 Oct;21:23-29. doi: 10.1016/j.pbi.2014.06.003. Epub 2014 Jul 1. Curr Opin Plant Biol. 2014. PMID: 24996032 Review.
MeSH terms
Substances
LinkOut - more resources
Full Text Sources
Research Materials
Miscellaneous