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Kim YJ, Kim WY, Somers DE. HOS15-mediated turnover of PRR7 enhances freezing tolerance. THE NEW PHYTOLOGIST 2024. [PMID: 39155726 DOI: 10.1111/nph.20062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2024] [Accepted: 07/29/2024] [Indexed: 08/20/2024]
Abstract
Arabidopsis PSEUDORESPONSE REGULATOR7 (PRR7) is a core component of the circadian oscillator which also plays a crucial role in freezing tolerance. PRR7 undergoes proteasome-dependent degradation to discretely phase maximal expression in early evening. While its repressive activity on downstream genes is integral to cold regulation, the mechanism of the conditional regulation of the PRR7 abundance is unknown. We used mutant analysis, protein interaction and ubiquitylation assays to establish that the ubiquitin ligase adaptor, HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENE 15 (HOS15), controls the protein accumulation pattern of PRR7 through direct protein-protein interactions at low temperatures. Freezing tolerance and electrolyte leakage assays show that PRR7 enhances cold temperature sensitivity, supported by ChIP-qPCR at C-REPEAT BINDING FACTOR1 (CBF1) and COLD-REGULATED 15A (COR15A) promoters where PRR7 levels were higher in hos15 mutants. HOS15 mediates PRR7 turnover through enhanced ubiquitylation at low temperature in the dark. Under the same conditions, increased PRR7 association with the promoters of CBFs and COR15A in hos15 correlates with decreased CBF1 and COR15A transcription and enhanced freezing sensitivity. We propose a novel mechanism whereby HOS15-mediated degradation of PRR7 provides an intersection between the circadian system and other cold acclimation pathways that lead to increased freezing tolerance.
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Affiliation(s)
- Yeon Jeong Kim
- Department of Molecular Genetics, The Ohio State University, Columbus, OH, 43210, USA
| | - Woe-Yeon Kim
- Division of Applied Life Science (BK21 Four), Plant Biological Rhythm Research Center (PBRRC), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Gyeongsang National University, Jinju, 52828, Korea
| | - David E Somers
- Department of Molecular Genetics, The Ohio State University, Columbus, OH, 43210, USA
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Kim YJ, Kim WY, Somers DE. HOS15-mediated turnover of PRR7 enhances freezing tolerance. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.20.599783. [PMID: 38979283 PMCID: PMC11230174 DOI: 10.1101/2024.06.20.599783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Arabidopsis PSEUDO RESPONSE REGULATOR7 (PRR7) is a core component of the circadian oscillator which also plays a crucial role in freezing tolerance. PRR7 undergoes proteasome-dependent degradation to discretely phase maximal expression in early evening. While its transcriptional repressive activity on downstream genes is integral to cold regulation, the mechanism of the conditional regulation of the PRR7 protein activity is unknown. We used double mutant analysis, protein interaction and ubiquitylation assays to establish that the ubiquitin ligase adaptor, HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENE 15 (HOS15), controls the protein accumulation pattern of PRR7 through direct protein-protein interactions. Freezing tolerance and electrolyte leakage assays show that PRR7 enhances cold temperature sensitivity, supported by ChIP-qPCR at C-REPEAT BINDING FACTOR (CBF) and COLD REGULATED 15A (COR15A) promoters where PRR7 levels were higher in hos15 mutants. We establish that HOS15 mediates PRR7 protein turnover through enhanced ubiquitylation at low temperature in the dark. Under the same conditions, increased PRR7 association with the promoter regions of CBFs and COR15A in hos15 correlates with decreased CBF1 and COR15A transcription and enhanced freezing sensitivity. We propose a novel mechanism whereby HOS15-mediated regulation of PRR7 provides an intersection between the circadian system and other cold acclimation pathways leading to freezing tolerance through upregulation of CBF1 and COR15A.
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Affiliation(s)
- Yeon Jeong Kim
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - Woe Yeon Kim
- Division of Applied Life Science (BK21 Four), Plant Biological Rhythm Research Center (PBRRC), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Gyeongsang National University, Jinju 52828, Republic of Korea
| | - David E Somers
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
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Rowson M, Jolly M, Dickson S, Gifford ML, Carré I. Timely symbiosis: circadian control of legume-rhizobia symbiosis. Biochem Soc Trans 2024; 52:1419-1430. [PMID: 38779952 DOI: 10.1042/bst20231307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 05/10/2024] [Accepted: 05/10/2024] [Indexed: 05/25/2024]
Abstract
Legumes house nitrogen-fixing endosymbiotic rhizobia in specialised polyploid cells within root nodules. This results in a mutualistic relationship whereby the plant host receives fixed nitrogen from the bacteria in exchange for dicarboxylic acids. This plant-microbe interaction requires the regulation of multiple metabolic and physiological processes in both the host and symbiont in order to achieve highly efficient symbiosis. Recent studies have showed that the success of symbiosis is influenced by the circadian clock of the plant host. Medicago and soybean plants with altered clock mechanisms showed compromised nodulation and reduced plant growth. Furthermore, transcriptomic analyses revealed that multiple genes with key roles in recruitment of rhizobia to plant roots, infection and nodule development were under circadian control, suggesting that appropriate timing of expression of these genes may be important for nodulation. There is also evidence for rhythmic gene expression of key nitrogen fixation genes in the rhizobium symbiont, and temporal coordination between nitrogen fixation in the bacterial symbiont and nitrogen assimilation in the plant host may be important for successful symbiosis. Understanding of how circadian regulation impacts on nodule establishment and function will identify key plant-rhizobial connections and regulators that could be targeted to increase the efficiency of this relationship.
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Affiliation(s)
- Monique Rowson
- School of Life Sciences, The University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, U.K
| | - Matthew Jolly
- School of Life Sciences, The University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, U.K
| | - Suzanna Dickson
- School of Life Sciences, The University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, U.K
| | - Miriam L Gifford
- School of Life Sciences, The University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, U.K
- The Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, The University of Warwick, Coventry CV4 7AL, U.K
| | - Isabelle Carré
- School of Life Sciences, The University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, U.K
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James AB, Sharples C, Laird J, Armstrong EM, Guo W, Tzioutziou N, Zhang R, Brown JWS, Nimmo HG, Jones MA. REVEILLE2 thermosensitive splicing: a molecular basis for the integration of nocturnal temperature information by the Arabidopsis circadian clock. THE NEW PHYTOLOGIST 2024; 241:283-297. [PMID: 37897048 DOI: 10.1111/nph.19339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Accepted: 09/27/2023] [Indexed: 10/29/2023]
Abstract
Cold stress is one of the major environmental factors that limit growth and yield of plants. However, it is still not fully understood how plants account for daily temperature fluctuations, nor how these temperature changes are integrated with other regulatory systems such as the circadian clock. We demonstrate that REVEILLE2 undergoes alternative splicing after chilling that increases accumulation of a transcript isoform encoding a MYB-like transcription factor. We explore the biological function of REVEILLE2 in Arabidopsis thaliana using a combination of molecular genetics, transcriptomics, and physiology. Disruption of REVEILLE2 alternative splicing alters regulatory gene expression, impairs circadian timing, and improves photosynthetic capacity. Changes in nuclear gene expression are particularly apparent in the initial hours following chilling, with chloroplast gene expression subsequently upregulated. The response of REVEILLE2 to chilling extends our understanding of plants immediate response to cooling. We propose that the circadian component REVEILLE2 restricts plants responses to nocturnal reductions in temperature, thereby enabling appropriate responses to daily environmental changes.
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Affiliation(s)
- Allan B James
- School of Molecular Biosciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Chantal Sharples
- School of Molecular Biosciences, University of Glasgow, Glasgow, G12 8QQ, UK
- RNA Biology and Molecular Physiology, Faculty for Biology, Bielefeld University, Universitaetsstrasse 25, 33615, Bielefeld, Germany
| | - Janet Laird
- School of Molecular Biosciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Emily May Armstrong
- School of Molecular Biosciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Wenbin Guo
- Information and Computational Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Nikoleta Tzioutziou
- Plant Sciences Division, College of Life Sciences, University of Dundee, Invergowrie, Dundee, DD2 5DA, UK
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Runxuan Zhang
- Information and Computational Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - John W S Brown
- Plant Sciences Division, College of Life Sciences, University of Dundee, Invergowrie, Dundee, DD2 5DA, UK
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Hugh G Nimmo
- School of Molecular Biosciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Matthew A Jones
- School of Molecular Biosciences, University of Glasgow, Glasgow, G12 8QQ, UK
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Marshall CM, Thompson VL, Creux NM, Harmer SL. The circadian clock controls temporal and spatial patterns of floral development in sunflower. eLife 2023; 12:80984. [PMID: 36637156 PMCID: PMC9977281 DOI: 10.7554/elife.80984] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Accepted: 01/12/2023] [Indexed: 01/14/2023] Open
Abstract
Biological rhythms are ubiquitous. They can be generated by circadian oscillators, which produce daily rhythms in physiology and behavior, as well as by developmental oscillators such as the segmentation clock, which periodically produces modular developmental units. Here, we show that the circadian clock controls the timing of late-stage floret development, or anthesis, in domesticated sunflowers. In these plants, up to thousands of individual florets are tightly packed onto a capitulum disk. While early floret development occurs continuously across capitula to generate iconic spiral phyllotaxy, during anthesis floret development occurs in discrete ring-like pseudowhorls with up to hundreds of florets undergoing simultaneous maturation. We demonstrate circadian regulation of floral organ growth and show that the effects of light on this process are time-of-day dependent. Delays in the phase of floral anthesis delay morning visits by pollinators, while disruption of circadian rhythms in floral organ development causes loss of pseudowhorl formation and large reductions in pollinator visits. We therefore show that the sunflower circadian clock acts in concert with environmental response pathways to tightly synchronize the anthesis of hundreds of florets each day, generating spatial patterns on the developing capitulum disk. This coordinated mass release of floral rewards at predictable times of day likely promotes pollinator visits and plant reproductive success.
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Affiliation(s)
- Carine M Marshall
- Department of Plant Biology, University of California, DavisDavisUnited States
| | - Veronica L Thompson
- Department of Plant Biology, University of California, DavisDavisUnited States
| | - Nicky M Creux
- Department of Plant Biology, University of California, DavisDavisUnited States
- Department of Plant and Soil Sciences, FABI, Innovation Africa, University of PretoriaPretoriaSouth Africa
| | - Stacey L Harmer
- Department of Plant Biology, University of California, DavisDavisUnited States
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Harmer SL, Fankhauser C, Webb AAR. Focus on circadian rhythms. PLANT PHYSIOLOGY 2022; 190:921-923. [PMID: 35900174 PMCID: PMC9516718 DOI: 10.1093/plphys/kiac353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 07/22/2022] [Indexed: 06/15/2023]
Affiliation(s)
| | - Christian Fankhauser
- Faculty of Biology and Medicine, Centre for Integrative Genomics, University of Lausanne, Génopode Building, Lausanne CH-1015, Switzerland
| | - Alex A R Webb
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
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