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Shtin M, Polverari L, Svolacchia N, Bertolotti G, Unterholzner SJ, Di Mambro R, Costantino P, Dello Ioio R, Sabatini S. The Mutual Inhibition between PLETHORAs and ARABIDOPSIS RESPONSE REGULATORs Controls Root Zonation. Plant Cell Physiol 2023; 64:317-324. [PMID: 36611272 DOI: 10.1093/pcp/pcad001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 12/10/2022] [Accepted: 01/04/2023] [Indexed: 06/17/2023]
Abstract
During organogenesis, a key step toward the development of a functional organ is the separation of cells into specific domains with different activities. Mutual inhibition of gene expression has been shown to be sufficient to establish and maintain these domains during organogenesis in several multicellular organisms. Here, we show that the mutual inhibition between the PLETHORA transcription factors (PLTs) and the ARABIDOPSIS RESPONSE REGULATORs (ARRs) transcription factors is sufficient to separate cell division and cell differentiation during root organogenesis. In particular, we show that ARR1 suppresses PLT activities and that PLTs suppress ARR1 and ARR12 by targeting their proteins for degradation via the KISS ME DEADLY 2 F-box protein. These findings reveal new important aspects of the complex process of root zonation and development.
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Affiliation(s)
- Margaryta Shtin
- Department of Biology and Biotechnology 'Charles Darwin', University of Rome 'Sapienza', via dei Sardi 70, Rome 00185, Italy
- Faculty of Science and Technology, Free University of Bozen-Bolzano, Piazzale Università 5, Bolzano 39100, Italy
| | - Laura Polverari
- Department of Biology and Biotechnology 'Charles Darwin', University of Rome 'Sapienza', via dei Sardi 70, Rome 00185, Italy
| | - Noemi Svolacchia
- Department of Biology and Biotechnology 'Charles Darwin', University of Rome 'Sapienza', via dei Sardi 70, Rome 00185, Italy
| | - Gaia Bertolotti
- Department of Biology and Biotechnology 'Charles Darwin', University of Rome 'Sapienza', via dei Sardi 70, Rome 00185, Italy
| | - Simon J Unterholzner
- Faculty of Science and Technology, Free University of Bozen-Bolzano, Piazzale Università 5, Bolzano 39100, Italy
| | - Riccardo Di Mambro
- Department of Biology, University of Pisa, via L. Ghini, 13, Pisa 56126, Italy
| | - Paolo Costantino
- Department of Biology and Biotechnology 'Charles Darwin', University of Rome 'Sapienza', via dei Sardi 70, Rome 00185, Italy
| | - Raffaele Dello Ioio
- Department of Biology and Biotechnology 'Charles Darwin', University of Rome 'Sapienza', via dei Sardi 70, Rome 00185, Italy
- Department of Biology, University of Pisa, via L. Ghini, 13, Pisa 56126, Italy
| | - Sabrina Sabatini
- Department of Biology and Biotechnology 'Charles Darwin', University of Rome 'Sapienza', via dei Sardi 70, Rome 00185, Italy
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Albertos P, Wlk T, Griffiths J, Pimenta Lange MJ, Unterholzner SJ, Rozhon W, Lange T, Jones AM, Poppenberger B. Brassinosteroid-regulated bHLH transcription factor CESTA induces the gibberellin 2-oxidase GA2ox7. Plant Physiol 2022; 188:2012-2025. [PMID: 35148416 PMCID: PMC8968292 DOI: 10.1093/plphys/kiac008] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 12/10/2021] [Indexed: 05/14/2023]
Abstract
Brassinosteroids (BRs) are plant steroids that have growth-promoting capacities, which are partly enabled by an ability to induce biosynthesis of gibberellins (GAs), a second class of plant hormones. In addition, BRs can also activate GA catabolism; here we show that in Arabidopsis (Arabidopsis thaliana) the basic helix-loop-helix transcription factor CESTA (CES) and its homologues BRASSINOSTEROID-ENHANCED EXPRESSION (BEE) 1 and 3 contribute to this activity. CES and the BEEs are BR-regulated at the transcriptional and posttranslational level and participate in different physiological processes, including vegetative and reproduction development, shade avoidance, and cold stress responses. We show that CES/BEEs can induce the expression of the class III GA 2-oxidase GA2ox7 and that this activity is increased by BRs. In BR signaling - and CES/BEE-deficient mutants, GA2ox7 expression decreased, yielding reduced levels of GA110, a product of GA2ox7 activity. In plants that over-express CES, GA2ox7 expression is hyper-responsive to BR, GA110 levels are elevated and amounts of bioactive GA are reduced. We provide evidence that CES directly binds to the GA2ox7 promoter and is activated by BRs, but can also act by BR-independent means. Based on these results, we propose a model for CES activity in GA catabolism where CES can be recruited for GA2ox7 induction not only by BR, but also by other factors.
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Affiliation(s)
| | | | | | - Maria J Pimenta Lange
- Institute of Plant Biology, Technical University of Braunschweig, Braunschweig, Germany
| | | | | | - Theo Lange
- Institute of Plant Biology, Technical University of Braunschweig, Braunschweig, Germany
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Unterholzner SJ, Rozhon W, Poppenberger B. Reply: Interaction between Brassinosteroids and Gibberellins: Synthesis or Signaling? In Arabidopsis, Both! Plant Cell 2016. [PMID: 27006486 DOI: 10.1105/tpc.16.0012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Affiliation(s)
- Simon J Unterholzner
- Biotechnology of Horticultural CropsTUM School of Life Sciences WeihenstephanTechnische Universität MünchenD-85354 Freising, Germany
| | - Wilfried Rozhon
- Biotechnology of Horticultural CropsTUM School of Life Sciences WeihenstephanTechnische Universität MünchenD-85354 Freising, Germany
| | - Brigitte Poppenberger
- Biotechnology of Horticultural CropsTUM School of Life Sciences WeihenstephanTechnische Universität MünchenD-85354 Freising, Germany
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Unterholzner SJ, Rozhon W, Poppenberger B. Reply: Interaction between Brassinosteroids and Gibberellins: Synthesis or Signaling? In Arabidopsis, Both! Plant Cell 2016; 28:836-9. [PMID: 27006486 PMCID: PMC4863389 DOI: 10.1105/tpc.16.00120] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 03/10/2016] [Accepted: 03/10/2016] [Indexed: 05/23/2023]
Affiliation(s)
- Simon J Unterholzner
- Biotechnology of Horticultural CropsTUM School of Life Sciences WeihenstephanTechnische Universität MünchenD-85354 Freising, Germany
| | - Wilfried Rozhon
- Biotechnology of Horticultural CropsTUM School of Life Sciences WeihenstephanTechnische Universität MünchenD-85354 Freising, Germany
| | - Brigitte Poppenberger
- Biotechnology of Horticultural CropsTUM School of Life Sciences WeihenstephanTechnische Universität MünchenD-85354 Freising, Germany
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Unterholzner SJ, Rozhon W, Papacek M, Ciomas J, Lange T, Kugler KG, Mayer KF, Sieberer T, Poppenberger B. Brassinosteroids Are Master Regulators of Gibberellin Biosynthesis in Arabidopsis. Plant Cell 2015; 27:2261-72. [PMID: 26243314 PMCID: PMC4568508 DOI: 10.1105/tpc.15.00433] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 07/08/2015] [Accepted: 07/21/2015] [Indexed: 05/18/2023]
Abstract
Plant growth and development are highly regulated processes that are coordinated by hormones including the brassinosteroids (BRs), a group of steroids with structural similarity to steroid hormones of mammals. Although it is well understood how BRs are produced and how their signals are transduced, BR targets, which directly confer the hormone's growth-promoting effects, have remained largely elusive. Here, we show that BRs regulate the biosynthesis of gibberellins (GAs), another class of growth-promoting hormones, in Arabidopsis thaliana. We reveal that Arabidopsis mutants deficient in BR signaling are severely impaired in the production of bioactive GA, which is correlated with defective GA biosynthetic gene expression. Expression of the key GA biosynthesis gene GA20ox1 in the BR signaling mutant bri1-301 rescues many of its developmental defects. We provide evidence that supports a model in which the BR-regulated transcription factor BES1 binds to a regulatory element in promoters of GA biosynthesis genes in a BR-induced manner to control their expression. In summary, our study underscores a role of BRs as master regulators of GA biosynthesis and shows that this function is of major relevance for the growth and development of vascular plants.
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Affiliation(s)
- Simon J Unterholzner
- Biotechnology of Horticultural Crops, TUM School of Life Sciences Weihenstephan, Technische Universität München, D-85354 Freising, Germany
| | - Wilfried Rozhon
- Biotechnology of Horticultural Crops, TUM School of Life Sciences Weihenstephan, Technische Universität München, D-85354 Freising, Germany
| | - Michael Papacek
- Biotechnology of Horticultural Crops, TUM School of Life Sciences Weihenstephan, Technische Universität München, D-85354 Freising, Germany
| | - Jennifer Ciomas
- Biotechnology of Horticultural Crops, TUM School of Life Sciences Weihenstephan, Technische Universität München, D-85354 Freising, Germany
| | - Theo Lange
- Institute of Plant Biology, Technical University of Braunschweig, D-38106 Braunschweig, Germany
| | - Karl G Kugler
- Plant Genome and System Biology, Helmholtz Center Munich, D-85764 Neuherberg, Germany
| | - Klaus F Mayer
- Plant Genome and System Biology, Helmholtz Center Munich, D-85764 Neuherberg, Germany
| | - Tobias Sieberer
- Plant Growth Regulation, TUM School of Life Sciences Weihenstephan, Technische Universität München, D-85354 Freising, Germany
| | - Brigitte Poppenberger
- Biotechnology of Horticultural Crops, TUM School of Life Sciences Weihenstephan, Technische Universität München, D-85354 Freising, Germany
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Unterholzner SJ, Hailer B, Poppenberger B, Rozhon W. Characterisation of the stbD/E toxin-antitoxin system of pEP36, a plasmid of the plant pathogen Erwinia pyrifoliae. Plasmid 2013; 70:216-25. [PMID: 23632277 DOI: 10.1016/j.plasmid.2013.04.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 04/15/2013] [Accepted: 04/17/2013] [Indexed: 11/29/2022]
Abstract
pEP36 is a plasmid ubiquitously present in Erwinia pyrifoliae, a pathogen which causes black stem blight of Asian pear. pEP36 is highly stable in its host, even in the absence of selective pressure. The plasmid is closely related to pEA29, which is widespread in E. amylovora, the causative agent of fire blight of apple and pear trees. Here we report that pEP36 possesses a functional hybrid toxin-antitoxin module, stbD/E(pEP36), with the toxin showing homology to the RelE/ParE proteins and the antidote belonging to the Phd/YefM antitoxin family. Bacteria expressing the StbE(pEP36) toxin arrest cell growth and enter a viable but non-culturable stage. However, they maintain their typical cell length and do not show filamentation. Pulse-chase experiments revealed that StbE(pEP36) acts as a global inhibitor of protein synthesis while it does not interfere with DNA and RNA synthesis. The StbD(pEP36) antitoxin is capable of neutralising StbE(pEP36) toxicity. Additional experiments show that the stbD/E(pEP36) module can stabilise plasmids at least 20-fold. Thus the toxin-antitoxin system may contribute to the remarkable stability of pEP36.
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Affiliation(s)
- Simon J Unterholzner
- Biotechnology of Horticultural Crops, Technische Universität München, Liesel-Beckmann-Straße 1, 85354 Freising, Germany.
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Unterholzner SJ, Poppenberger B, Rozhon W. Toxin-antitoxin systems: Biology, identification, and application. Mob Genet Elements 2013; 3:e26219. [PMID: 24251069 PMCID: PMC3827094 DOI: 10.4161/mge.26219] [Citation(s) in RCA: 223] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 08/16/2013] [Accepted: 08/19/2013] [Indexed: 02/07/2023] Open
Abstract
Toxin–antitoxin (TA) systems are small genetic elements composed of a toxin gene and its cognate antitoxin. The toxins of all known TA systems are proteins while the antitoxins are either proteins or non-coding RNAs. Based on the molecular nature of the antitoxin and its mode of interaction with the toxin the TA modules are currently grouped into five classes. In general, the toxin is more stable than the antitoxin but the latter is expressed to a higher level. If supply of the antitoxin stops, for instance under special growth conditions or by plasmid loss in case of plasmid encoded TA systems, the antitoxin is rapidly degraded and can no longer counteract the toxin. Consequently, the toxin becomes activated and can act on its cellular targets. Typically, TA toxins act on crucial cellular processes including translation, replication, cytoskeleton formation, membrane integrity, and cell wall biosynthesis. TA systems and their components are also versatile tools for a multitude of purposes in basic research and biotechnology. Currently, TA systems are frequently used for selection in cloning and for single protein expression in living bacterial cells. Since several TA toxins exhibit activity in yeast and mammalian cells they may be useful for applications in eukaryotic systems. TA modules are also considered as promising targets for the development of antibacterial drugs and their potential to combat viral infection may aid in controlling infectious diseases.
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Affiliation(s)
- Simon J Unterholzner
- 1 Biotechnology of Horticultural Crops; Technische Universität München; Freising, Germany
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