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Kaji T, Matsumoto K, Okumura T, Nakayama M, Hoshino S, Takaoka Y, Wang J, Ueda M. Two distinct modes of action of molecular glues in the plant hormone co-receptor COI1-JAZ system. iScience 2024; 27:108625. [PMID: 38188528 PMCID: PMC10770490 DOI: 10.1016/j.isci.2023.108625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Revised: 10/16/2023] [Accepted: 11/30/2023] [Indexed: 01/09/2024] Open
Abstract
The plant hormone (3R, 7S)-jasmonoyl-L-isoleucine ((3R, 7S)-JA-Ile) is perceived by the COI1-JAZ co-receptor in Arabidopsis thaliana, leading to the activation of gene expression for plant defense responses, growth, development, and other processes. Therefore, understanding the interaction between the COI1-JAZ co-receptor and its ligands is essential for the development of COI1-JAZ agonists and antagonists as potent chemical tools for regulating (3R, 7S)-JA-Ile signaling. This study demonstrated that COI1-JAZ has two independent modes of ligand perception using a differential scanning fluorimetry (DSF) assay. (3R, 7S)-JA-Ile is perceived through a one-step model in which (3R, 7S)-JA-Ile causes protein-protein interaction between COI1 and JAZ. In contrast, coronatine (COR), a mimic of (3R, 7S)-JA-Ile, is perceived through a two-step model in which COR is first perceived by COI1 and then recruits JAZ to form the COI1-COR-JAZ complex. Our results demonstrate two distinct modes of action of molecular glues causing protein-protein interactions.
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Affiliation(s)
- Takuya Kaji
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Kotaro Matsumoto
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Taichi Okumura
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Misuzu Nakayama
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Shunji Hoshino
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Science, Tohoku University, Sendai 980-8578, Japan
| | - Yousuke Takaoka
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Jianxin Wang
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Minoru Ueda
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Science, Tohoku University, Sendai 980-8578, Japan
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2
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Kępczyński J, Kępczyńska E. Plant-Derived Smoke and Karrikin 1 in Seed Priming and Seed Biotechnology. PLANTS (BASEL, SWITZERLAND) 2023; 12:2378. [PMID: 37376003 DOI: 10.3390/plants12122378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 06/16/2023] [Accepted: 06/17/2023] [Indexed: 06/29/2023]
Abstract
Plant-derived smoke and smoke water (SW) can stimulate seed germination in numerous plants from fire-prone and fire-free areas, including cultivated plants and agricultural weeds. Smoke contains thousands of compounds; only several stimulants and inhibitors have been isolated from smoke. Among the six karrikins present in smoke, karrikin 1 (KAR1) seems to be key for the stimulating effect of smoke. The discovery and activity of highly diluted SW and KAR1 at extremely low concentrations (even at ca. 10-9 M) inducing seed germination of a wide array of horticultural and agricultural plants have created tremendous opportunities for the use of these factors in pre-sowing seed treatment through smoke- or KAR1-priming. This review presents examples of effects exerted by the two types of priming on seed germination and seedling emergence, growth, and development, as well as on the content of some compounds and enzyme activity. Seed biotechnology may involve both SW and KAR1. Some examples demonstrate that SW and/or KAR1 increased the efficiency of somatic embryogenesis, somatic embryo germination and conversion to plantlets. It is also possible to stimulate in vitro seed germination by SW, which allows to use in orchid propagation.
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Affiliation(s)
- Jan Kępczyński
- Institute of Biology, University of Szczecin, Waska 13, 71-415 Szczecin, Poland
| | - Ewa Kępczyńska
- Institute of Biology, University of Szczecin, Waska 13, 71-415 Szczecin, Poland
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Guercio AM, Palayam M, Shabek N. Strigolactones: diversity, perception, and hydrolysis. PHYTOCHEMISTRY REVIEWS : PROCEEDINGS OF THE PHYTOCHEMICAL SOCIETY OF EUROPE 2023; 22:339-360. [PMID: 37201177 PMCID: PMC10191409 DOI: 10.1007/s11101-023-09853-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 01/03/2023] [Indexed: 05/20/2023]
Abstract
Strigolactones (SLs) are a unique and novel class of phytohormones that regulate numerous processes of growth and development in plants. Besides their endogenous functions as hormones, SLs are exuded by plant roots to stimulate critical interactions with symbiotic fungi but can also be exploited by parasitic plants to trigger their seed germination. In the past decade, since their discovery as phytohormones, rapid progress has been made in understanding the SL biosynthesis and signaling pathway. Of particular interest are the diversification of natural SLs and their exact mode of perception, selectivity, and hydrolysis by their dedicated receptors in plants. Here we provide an overview of the emerging field of SL perception with a focus on the diversity of canonical, non-canonical, and synthetic SL probes. Moreover, this review offers useful structural insights into SL perception, the precise molecular adaptations that define receptor-ligand specificities, and the mechanisms of SL hydrolysis and its attenuation by downstream signaling components.
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Affiliation(s)
- Angelica M Guercio
- Department of Plant Biology, College of Biological Sciences, University of California - Davis, Davis, CA 95616, USA
| | - Malathy Palayam
- Department of Plant Biology, College of Biological Sciences, University of California - Davis, Davis, CA 95616, USA
| | - Nitzan Shabek
- Department of Plant Biology, College of Biological Sciences, University of California - Davis, Davis, CA 95616, USA
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4
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Waters MT, Nelson DC. Karrikin perception and signalling. THE NEW PHYTOLOGIST 2023; 237:1525-1541. [PMID: 36333982 DOI: 10.1111/nph.18598] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Accepted: 09/29/2022] [Indexed: 06/16/2023]
Abstract
Karrikins (KARs) are a class of butenolide compounds found in smoke that were first identified as seed germination stimulants for fire-following species. Early studies of KARs classified the germination and postgermination responses of many plant species and investigated crosstalk with plant hormones that regulate germination. The discovery that Arabidopsis thaliana responds to KARs laid the foundation for identifying mutants with altered KAR responses. Genetic analysis of KAR signalling revealed an unexpected link to strigolactones (SLs), a class of carotenoid-derived plant hormones. Substantial progress has since been made towards understanding how KARs are perceived and regulate plant growth, in no small part due to advances in understanding SL perception. KAR and SL signalling systems are evolutionarily related and retain a high degree of similarity. There is strong evidence that KARs are natural analogues of an endogenous signal(s), KAI2 ligand (KL), which remains unknown. KAR/KL signalling regulates many developmental processes in plants including germination, seedling photomorphogenesis, and root and root hair growth. KAR/KL signalling also affects abiotic stress responses and arbuscular mycorrhizal symbiosis. Here, we summarise the current knowledge of KAR/KL signalling and discuss current controversies and unanswered questions in this field.
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Affiliation(s)
- Mark T Waters
- School of Molecular Sciences, University of Western Australia, Perth, WA, 6009, Australia
| | - David C Nelson
- Department of Botany and Plant Sciences, University of California, Riverside, CA, 92521, USA
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5
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Martinez SE, Conn CE, Guercio AM, Sepulveda C, Fiscus CJ, Koenig D, Shabek N, Nelson DC. A KARRIKIN INSENSITIVE2 paralog in lettuce mediates highly sensitive germination responses to karrikinolide. PLANT PHYSIOLOGY 2022; 190:1440-1456. [PMID: 35809069 PMCID: PMC9516758 DOI: 10.1093/plphys/kiac328] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 05/26/2022] [Indexed: 06/15/2023]
Abstract
Karrikins (KARs) are chemicals in smoke that can enhance germination of many plants. Lettuce (Lactuca sativa) cv. Grand Rapids germinates in response to nanomolar karrikinolide (KAR1). Lettuce is much less responsive to KAR2 or a mixture of synthetic strigolactone analogs, rac-GR24. We investigated the molecular basis of selective and sensitive KAR1 perception in lettuce. The lettuce genome contains two copies of KARRIKIN INSENSITIVE2 (KAI2), which in Arabidopsis (Arabidopsis thaliana) encodes a receptor that is required for KAR responses. LsKAI2b is more highly expressed than LsKAI2a in dry achenes and during early stages of imbibition. Through cross-species complementation assays in Arabidopsis, we found that an LsKAI2b transgene confers robust responses to KAR1, but LsKAI2a does not. Therefore, LsKAI2b likely mediates KAR1 responses in lettuce. We compared homology models of KAI2 proteins from lettuce and a fire-follower, whispering bells (Emmenanthe penduliflora). This identified pocket residues 96, 124, 139, and 161 as candidates that influence the ligand specificity of KAI2. Further support for the importance of these residues was found through a broader comparison of pocket residues among 281 KAI2 proteins from 184 asterid species. Almost all KAI2 proteins had either Tyr or Phe identity at position 124. Genes encoding Y124-type KAI2 are more broadly distributed in asterids than in F124-type KAI2. Substitutions at residues 96, 124, 139, and 161 in Arabidopsis KAI2 produced a broad array of responses to KAR1, KAR2, and rac-GR24. This suggests that the diverse ligand preferences observed among KAI2 proteins in plants could have evolved through relatively few mutations.
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Affiliation(s)
- Stephanie E Martinez
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521, USA
| | - Caitlin E Conn
- Department of Biology, Berry College, Mount Berry, Georgia 30149, USA
| | - Angelica M Guercio
- Department of Plant Biology, University of California, Davis, California 95616, USA
| | - Claudia Sepulveda
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521, USA
| | - Christopher J Fiscus
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521, USA
| | - Daniel Koenig
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521, USA
| | - Nitzan Shabek
- Department of Plant Biology, University of California, Davis, California 95616, USA
| | - David C Nelson
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521, USA
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6
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Bürger M, Honda K, Kondoh Y, Hong S, Watanabe N, Osada H, Chory J. Crystal structure of Arabidopsis DWARF14-LIKE2 (DLK2) reveals a distinct substrate binding pocket architecture. PLANT DIRECT 2022; 6:e446. [PMID: 36172078 PMCID: PMC9470386 DOI: 10.1002/pld3.446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 08/14/2022] [Accepted: 08/17/2022] [Indexed: 06/16/2023]
Abstract
In Arabidopsis thaliana, the Sigma factor B regulator RsbQ-like family of α/β hydrolases contains the strigolactone (SL) receptor DWARF14 (AtD14), the karrikin receptor KARRIKIN INSENSITIVE2 (AtKAI2), and DWARF14-LIKE2 (AtDLK2), a protein of unknown function. Despite very similar protein folds, AtD14 and AtKAI2 differ in size and architecture of their ligand binding pockets, influencing their substrate specificity. We present the 1.5 Å crystal structure of AtDLK2, revealing the smallest ligand binding pocket in the protein family, bordered by two unique glycine residues. We identified a gatekeeper residue in the protein's lid domain and present a pyrrolo-quinoline-dione compound that inhibits AtDLK2's enzymatic activity.
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Affiliation(s)
- Marco Bürger
- Plant Biology LaboratorySalk Institute for Biological StudiesLa JollaCaliforniaUSA
| | - Kaori Honda
- Chemical Biology Research GroupRIKEN Centre for Sustainable Resource ScienceWakoSaitamaJapan
| | - Yasumitsu Kondoh
- Chemical Biology Research GroupRIKEN Centre for Sustainable Resource ScienceWakoSaitamaJapan
| | - Sharon Hong
- Plant Biology LaboratorySalk Institute for Biological StudiesLa JollaCaliforniaUSA
| | - Nobumoto Watanabe
- Bioprobe Application Research UnitRIKEN Centre for Sustainable Resource ScienceWakoSaitamaJapan
| | - Hiroyuki Osada
- Chemical Biology Research GroupRIKEN Centre for Sustainable Resource ScienceWakoSaitamaJapan
| | - Joanne Chory
- Plant Biology LaboratorySalk Institute for Biological StudiesLa JollaCaliforniaUSA
- Howard Hughes Medical InstituteSalk Institute for Biological StudiesLa JollaCaliforniaUSA
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7
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Bonhomme S, Guillory A. Synthesis and signalling of strigolactone and KAI2-ligand signals in bryophytes. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:4487-4495. [PMID: 35524989 DOI: 10.1093/jxb/erac186] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 05/04/2022] [Indexed: 06/14/2023]
Abstract
Strigolactones (SLs), long known as butenolide rhizospheric signals, have been recognized since 2008 as a class of hormones regulating many aspects of plant development. Many authors also anticipate 'KAI2-ligand' (KL) as a novel class of phytohormones; however, this ligand remains elusive. Core genes of SL and KL pathways, first described in angiosperms, are found in all land plants and some even in green algae. This review reports current knowledge of these pathways in bryophytes. Data on the pathways mostly come from two models: the moss Physcomitrium patens and the liverwort Marchantia. Gene targeting methods have allowed functional analyses of both models. Recent work in Marchantia suggests that SLs' ancestral role was to recruit beneficial microbes as arbuscular mycorrhizal fungi. In contrast, the hormonal role of SLs observed in P. patens is probably a result of convergent evolution. Evidence for a functional KL pathway in both bryophyte models is very recent. Nevertheless, many unknowns remain and warrant a more extensive investigation of SL and KL pathways in various land plant lineages.
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Affiliation(s)
- Sandrine Bonhomme
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), 78000 Versailles, France
| | - Ambre Guillory
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), 78000 Versailles, France
- Laboratoire des Interactions Plantes - Microbes - Environnement (LIPME), Université de Toulouse, INRAE, CNRS, 24 Chemin de Borde Rouge, 31320 Castanet-Tolosan, France
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8
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Dani KGS, Loreto F. Plant volatiles as regulators of hormone homeostasis. THE NEW PHYTOLOGIST 2022; 234:804-812. [PMID: 35170033 DOI: 10.1111/nph.18035] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 01/24/2022] [Indexed: 06/14/2023]
Abstract
Some canonical plant hormones such as auxins and gibberellins have precursors that are biogenic volatiles (indole, indole acetonitrile, phenylacetaldoxime and ent-kaurene). Cytokinins, abscisic acid and strigolactones are hormones comprising chemical moieties that have distinct volatile analogues, and are synthesised alongside constitutively emitted volatiles (isoprene, sesquiterpenes, lactones, benzenoids and apocarotenoid volatiles). Nonvolatile hormone analogues and biogenic volatile organic compounds (BVOCs) evolved in tandem as growth and behavioural regulators in unicellular organisms. In plants, however, nonvolatile hormones evolved as regulators of growth, development and differentiation, while endogenous BVOCs (often synthesised lifelong) became subtle regulators of hormone synthesis, availability, activity and turnover, all supported by functionally redundant components of hormone metabolism. Reciprocal changes in the abundance and activity of hormones, nitric oxide, and constitutive plant volatiles constantly bridge retrograde and anterograde signalling to maintain hormone equilibria even in unstressed plants. This is distinct from transient interference in hormone signalling by stress-induced and exogenously received volatiles.
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Affiliation(s)
- Kaidala Ganesha Srikanta Dani
- Institute of Sustainable Plant Protection, National Research Council of Italy, Via Madonna del Piano 10, Sesto Fiorentino, Florence, 50019, Italy
- Department of Biology, Agriculture and Food Sciences, National Research Council of Italy, Piazzale Aldo Moro 7, Rome, 00185, Italy
| | - Francesco Loreto
- Institute of Sustainable Plant Protection, National Research Council of Italy, Via Madonna del Piano 10, Sesto Fiorentino, Florence, 50019, Italy
- Department of Biology, University of Naples Federico II, Via Cinthia, Naples, 80126, Italy
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9
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Wang Q, Smith SM, Huang J. Origins of strigolactone and karrikin signaling in plants. TRENDS IN PLANT SCIENCE 2022; 27:450-459. [PMID: 34876337 DOI: 10.1016/j.tplants.2021.11.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 11/08/2021] [Accepted: 11/09/2021] [Indexed: 06/13/2023]
Abstract
Strigolactones (SLs) and karrikins (KARs) are butenolides that influence multiple aspects of plant growth and development. D14 and KAI2 are members of the α/β-fold hydrolase superfamily and act as receptors of SLs and KARs, as well as of unidentified endogenous KAI2-ligands (KLs). Phylogenetic analyses suggest that plant KAI2 was derived from bacterial RsbQ via horizontal gene transfer (HGT) before the emergence of streptophytes. The D14/KAI2 and RsbQ proteins share conserved tertiary structures and functional features. In this opinion article, we suggest that the acquisition of RsbQ by plant cells was fundamental to the formation of butenolide sensing systems. Recruitment of additional signal transduction components and gene duplication subsequently led to versatile butenolide signaling systems throughout land plants.
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Affiliation(s)
- Qia Wang
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Yunnan Key Laboratory for Fungal Diversity and Green Development, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - Steven M Smith
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, School of Natural Sciences, University of Tasmania, Hobart 7001, Australia.
| | - Jinling Huang
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Yunnan Key Laboratory for Fungal Diversity and Green Development, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng 475004, China; Department of Biology, East Carolina University, Greenville, NC 27858, USA.
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10
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Liu X, Zhang J. In Silico Investigation on KAR Signaling Reveals the Significant Dynamic Change of Its Receptor's Structure. J Chem Inf Model 2022; 62:1933-1941. [PMID: 35389657 DOI: 10.1021/acs.jcim.2c00004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Karrikins (KARs) have been identified as a class of smoke-derived plant growth regulators widely functioning among angiosperms. However, little is known about the mechanism by which these molecules trigger the relevant signal transduction. In this research, conventional molecular dynamics simulations were used to investigate the dynamical behavior of the apo- and holo-forms of the KAR receptor KAI2. The results show that the dynamic binding conformation of KAR1 in the active site is not completely consistent with that in the static crystal and is largely affected by the residue segment of the receptor, Tyr150-Asn180. The binding of the ligand with KAI2 changes the distribution of the electrostatic potential near the active site and drives the conformational transition of the Tyr150-Asn180 segment with strong internal positive correlation. A "dual induction" signaling mechanism is proposed in view of the present calculations. Our work paves way for in-depth understanding of the KAR signal transduction mechanism and sheds light on further experimental and theoretical exploration.
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Affiliation(s)
- Xiaoting Liu
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130023, Jilin, People's Republic of China.,College of Food Science and Engineering, National Engineering Laboratory of Wheat and Corn Deep Processing, Jilin Agricultural University, Changchun 130118, Jilin, People's Republic of China
| | - Jilong Zhang
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130023, Jilin, People's Republic of China
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11
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Sepulveda C, Guzmán MA, Li Q, Villaécija-Aguilar JA, Martinez SE, Kamran M, Khosla A, Liu W, Gendron JM, Gutjahr C, Waters MT, Nelson DC. KARRIKIN UP-REGULATED F-BOX 1 (KUF1) imposes negative feedback regulation of karrikin and KAI2 ligand metabolism in Arabidopsis thaliana. Proc Natl Acad Sci U S A 2022; 119:e2112820119. [PMID: 35254909 PMCID: PMC8931227 DOI: 10.1073/pnas.2112820119] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 01/28/2022] [Indexed: 12/13/2022] Open
Abstract
SignificanceKarrikins are chemicals in smoke that stimulate regrowth of many plants after fire. However, karrikin responses are not limited to species from fire-prone environments and can affect growth after germination. Putatively, this is because karrikins mimic an unknown signal in plants, KAI2 ligand (KL). Karrikins likely require modification in plants to become bioactive. We identify a gene, KUF1, that appears to negatively regulate biosynthesis of KL and metabolism of a specific karrikin. KUF1 expression increases in response to karrikin or KL signaling, thus forming a negative feedback loop that limits further activation of the signaling pathway. This discovery will advance understanding of how karrikins are perceived and how smoke-activated germination evolved. It will also aid identification of the elusive KL.
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Affiliation(s)
- Claudia Sepulveda
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521
| | - Michael A. Guzmán
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521
| | - Qingtian Li
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521
| | | | - Stephanie E. Martinez
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521
| | - Muhammad Kamran
- School of Molecular Sciences, University of Western Australia, Perth, WA 6009, Australia
| | - Aashima Khosla
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521
| | - Wei Liu
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06511
| | - Joshua M. Gendron
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06511
| | - Caroline Gutjahr
- Plant Genetics, TUM School of Life Sciences, Technical University of Munich, Freising, 85354 Germany
| | - Mark T. Waters
- School of Molecular Sciences, University of Western Australia, Perth, WA 6009, Australia
| | - David C. Nelson
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521
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12
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Li Q, Martín-Fontecha ES, Khosla A, White AR, Chang S, Cubas P, Nelson DC. The strigolactone receptor D14 targets SMAX1 for degradation in response to GR24 treatment and osmotic stress. PLANT COMMUNICATIONS 2022; 3:100303. [PMID: 35529949 PMCID: PMC9073322 DOI: 10.1016/j.xplc.2022.100303] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 12/15/2021] [Accepted: 01/25/2022] [Indexed: 05/25/2023]
Abstract
The effects of the phytohormone strigolactone (SL) and smoke-derived karrikins (KARs) on plants are generally distinct, despite the fact that they are perceived through very similar mechanisms. The homologous receptors DWARF14 (D14) and KARRIKIN-INSENSITIVE2 (KAI2), together with the F-box protein MORE AXILLARY GROWTH2 (MAX2), mediate SL and KAR responses, respectively, by targeting different SMAX1-LIKE (SMXL) family proteins for degradation. These mechanisms are putatively well-insulated, with D14-MAX2 targeting SMXL6, SMXL7, and SMXL8 and KAI2-MAX2 targeting SMAX1 and SMXL2 in Arabidopsis thaliana. Recent evidence challenges this model. We investigated whether D14 can target SMAX1 and whether this occurs naturally. Genetic analysis indicates that the SL analog GR24 promotes D14-SMAX1 crosstalk. Although D14 shows weaker interactions with SMAX1 than with SMXL2 or SMXL7, D14 mediates GR24-induced degradation of SMAX1 in plants. Osmotic stress triggers SMAX1 degradation, which is protective, through SL biosynthesis and signaling genes. Thus, D14-SMAX1 crosstalk may be beneficial and not simply a vestige of the evolution of the SL pathway.
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Affiliation(s)
- Qingtian Li
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA
| | - Elena Sánchez Martín-Fontecha
- Plant Molecular Genetics Department, Centro Nacional de Biotecnología/CSIC, Campus Universidad Autόnoma de Madrid, Madrid, Spain
| | - Aashima Khosla
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA
| | - Alexandra R.F. White
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA
| | - Sunhyun Chang
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA
| | - Pilar Cubas
- Plant Molecular Genetics Department, Centro Nacional de Biotecnología/CSIC, Campus Universidad Autόnoma de Madrid, Madrid, Spain
| | - David C. Nelson
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA
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13
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White ARF, Mendez JA, Khosla A, Nelson DC. Rapid analysis of strigolactone receptor activity in a Nicotiana benthamiana dwarf14 mutant. PLANT DIRECT 2022; 6:e389. [PMID: 35355884 PMCID: PMC8948499 DOI: 10.1002/pld3.389] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 12/03/2021] [Accepted: 02/17/2022] [Indexed: 05/29/2023]
Abstract
DWARF14 (D14) is an ɑ/β-hydrolase and receptor for the plant hormone strigolactone (SL) in angiosperms. Upon SL perception, D14 works with MORE AXILLARY GROWTH2 (MAX2) to trigger polyubiquitination and degradation of DWARF53(D53)-type proteins in the SUPPRESSOR OF MAX2 1-LIKE (SMXL) family. We used CRISPR-Cas9 to generate knockout alleles of the two homoeologous D14 genes in the Nicotiana benthamiana genome. The Nbd14a,b double mutant had several phenotypes that are consistent with the loss of SL perception in other plants, including increased axillary bud outgrowth, reduced height, shortened petioles, and smaller leaves. A ratiometric fluorescent reporter system was used to monitor degradation of SMXL7 from Arabidopsis thaliana (AtSMXL7) after transient expression in N. benthamiana and treatment with the strigolactone analog GR24. AtSMXL7 was degraded after treatment with GR245DS, which has the stereochemical configuration of natural SLs, as well as its enantiomer GR24 ent-5DS. In Nbd14a,b leaves, AtSMXL7 abundance was unaffected by rac-GR24 or either GR24 stereoisomer. Transient coexpression of AtD14 with the AtSMXL7 reporter in Nbd14a,b restored the degradation response to rac-GR24, but required an active catalytic triad. We used this platform to evaluate the ability of several AtD14 mutants that had not been characterized in plants to target AtSMXL7 for degradation.
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Affiliation(s)
- Alexandra R. F. White
- Department of Botany and Plant SciencesUniversity of CaliforniaRiversideCaliforniaUSA
| | - Jose A. Mendez
- Department of Botany and Plant SciencesUniversity of CaliforniaRiversideCaliforniaUSA
| | - Aashima Khosla
- Department of Botany and Plant SciencesUniversity of CaliforniaRiversideCaliforniaUSA
| | - David C. Nelson
- Department of Botany and Plant SciencesUniversity of CaliforniaRiversideCaliforniaUSA
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14
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Arellano-Saab A, McErlean CSP, Lumba S, Savchenko A, Stogios PJ, McCourt P. A novel strigolactone receptor antagonist provides insights into the structural inhibition, conditioning, and germination of the crop parasite Striga. J Biol Chem 2022; 298:101734. [PMID: 35181340 PMCID: PMC9035408 DOI: 10.1016/j.jbc.2022.101734] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 02/12/2022] [Accepted: 02/14/2022] [Indexed: 01/14/2023] Open
Abstract
Crop parasites of the Striga genera are a major biological deterrent to food security in Africa and are one of the largest obstacles to poverty alleviation on the continent. Striga seeds germinate by sensing small-molecule hormones, strigolactones (SLs), that emanate from host roots. Although SL receptors (Striga hermonthica HYPOSENSITIVE TO LIGHT [ShHTL]) have been identified, discerning their function has been difficult because these parasites cannot be easily grown under laboratory conditions. Moreover, many Striga species are obligate outcrossers that are not transformable, hence not amenable to genetic analysis. By combining phenotypic screening with ShHTL structural information and hybrid drug discovery methods, we discovered a potent SL perception inhibitor for Striga, dormirazine (DOZ). Structural analysis of this piperazine-based antagonist reveals a novel binding mechanism, distinct from that of known SLs, blocking access of the hormone to its receptor. Furthermore, DOZ reduces the flexibility of protein–protein interaction domains important for receptor signaling to downstream partners. In planta, we show, via temporal additions of DOZ, that SL receptors are required at a specific time during seed conditioning. This conditioning is essential to prime seed germination at the right time; thus, this SL-sensitive stage appears to be critical for adequate receptor signaling. Aside from uncovering a function for ShHTL during seed conditioning, these results suggest that future Ag-Biotech Solutions to Striga infestations will need to carefully time the application of antagonists to exploit receptor availability and outcompete natural SLs, critical elements for successful parasitic plant invasions.
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Affiliation(s)
- Amir Arellano-Saab
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto M5S 3B2, Canada; Department of Chemical Engineering and Applied Chemistry, University of Toronto. Toronto, ON. M5S 3E5, Canada
| | | | - Shelley Lumba
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto M5S 3B2, Canada
| | - Alexei Savchenko
- Department of Chemical Engineering and Applied Chemistry, University of Toronto. Toronto, ON. M5S 3E5, Canada; Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Peter J Stogios
- Department of Chemical Engineering and Applied Chemistry, University of Toronto. Toronto, ON. M5S 3E5, Canada
| | - Peter McCourt
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto M5S 3B2, Canada
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15
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Guercio AM, Torabi S, Cornu D, Dalmais M, Bendahmane A, Le Signor C, Pillot JP, Le Bris P, Boyer FD, Rameau C, Gutjahr C, de Saint Germain A, Shabek N. Structural and functional analyses explain Pea KAI2 receptor diversity and reveal stereoselective catalysis during signal perception. Commun Biol 2022; 5:126. [PMID: 35149763 PMCID: PMC8837635 DOI: 10.1038/s42003-022-03085-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 01/28/2022] [Indexed: 11/10/2022] Open
Abstract
KAI2 proteins are plant α/β hydrolase receptors which perceive smoke-derived butenolide signals and endogenous, yet unidentified KAI2-ligands (KLs). The number of functional KAI2 receptors varies among species and KAI2 gene duplication and sub-functionalization likely plays an adaptative role by altering specificity towards different KLs. Legumes represent one of the largest families of flowering plants and contain many agronomic crops. Prior to their diversification, KAI2 underwent duplication resulting in KAI2A and KAI2B. Here we demonstrate that Pisum sativum KAI2A and KAI2B are active receptors and enzymes with divergent ligand stereoselectivity. KAI2B has a higher affinity for and hydrolyses a broader range of substrates including strigolactone-like stereoisomers. We determine the crystal structures of PsKAI2B in apo and butenolide-bound states. The biochemical, structural, and mass spectra analyses of KAI2s reveal a transient intermediate on the catalytic serine and a stable adduct on the catalytic histidine, confirming its role as a bona fide enzyme. Our work uncovers the stereoselectivity of ligand perception and catalysis by diverged KAI2 receptors and proposes adaptive sensitivity to KAR/KL and strigolactones by KAI2B.
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Affiliation(s)
- Angelica M Guercio
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, 95616, USA
| | - Salar Torabi
- Plant Genetics, TUM School of Life Sciences, Technical University of Munich (TUM), 85354, Freising, Germany
| | - David Cornu
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Marion Dalmais
- Institute of Plant Sciences Paris-Saclay, INRAE, CNRS, Université Paris-Saclay, 91405, Orsay, France
| | - Abdelhafid Bendahmane
- Institute of Plant Sciences Paris-Saclay, INRAE, CNRS, Université Paris-Saclay, 91405, Orsay, France
| | - Christine Le Signor
- Agroecologie, AgroSup Dijon, INRAE, Université Bourgogne Franche Comte, 21000, Dijon, France
| | - Jean-Paul Pillot
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, 78000, Versailles, France
| | - Philippe Le Bris
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, 78000, Versailles, France
| | - François-Didier Boyer
- Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, UPR 2301, 91198, Gif-sur-Yvette, France
| | - Catherine Rameau
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, 78000, Versailles, France
| | - Caroline Gutjahr
- Plant Genetics, TUM School of Life Sciences, Technical University of Munich (TUM), 85354, Freising, Germany
| | | | - Nitzan Shabek
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, 95616, USA.
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16
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Kyozuka J, Nomura T, Shimamura M. Origins and evolution of the dual functions of strigolactones as rhizosphere signaling molecules and plant hormones. CURRENT OPINION IN PLANT BIOLOGY 2022; 65:102154. [PMID: 34923261 DOI: 10.1016/j.pbi.2021.102154] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 11/13/2021] [Accepted: 11/18/2021] [Indexed: 06/14/2023]
Abstract
Strigolactones (SLs) play roles as a class of plant hormones and rhizosphere signaling chemicals that induce hyphal branching of arbuscular mycorrhizal fungi and seed germination of parasitic plants. Therefore, SLs have dual functions. Recent progress in genome sequencing and genetic studies of bryophytes and algae has begun to shed light on the origin and evolution of these two functions of SLs.
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Affiliation(s)
- Junko Kyozuka
- Graduate School of Life Sciences, Tohoku University, Sendai, Japan.
| | - Takahito Nomura
- Center for Bioscience Research and Education, Utsunomiya University, Tochigi, Japan
| | - Masaki Shimamura
- Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
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17
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Bürger M. Insights into the evolution of strigolactone signaling. THE PLANT CELL 2021; 33:3389-3390. [PMID: 35233610 PMCID: PMC8566212 DOI: 10.1093/plcell/koab216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 08/23/2021] [Indexed: 05/25/2023]
Affiliation(s)
- Marco Bürger
- Assistant Features Editor, The Plant Cell, American Society of Plant Biologists, Rockville, MD, USA
- Plant Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
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18
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Lopez-Obando M, Guillory A, Boyer FD, Cornu D, Hoffmann B, Le Bris P, Pouvreau JB, Delavault P, Rameau C, de Saint Germain A, Bonhomme S. The Physcomitrium (Physcomitrella) patens PpKAI2L receptors for strigolactones and related compounds function via MAX2-dependent and -independent pathways. THE PLANT CELL 2021; 33:3487-3512. [PMID: 34459915 PMCID: PMC8662777 DOI: 10.1093/plcell/koab217] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 08/24/2021] [Indexed: 05/20/2023]
Abstract
In angiosperms, the α/β hydrolase DWARF14 (D14), along with the F-box protein MORE AXILLARY GROWTH2 (MAX2), perceives strigolactones (SL) to regulate developmental processes. The key SL biosynthetic enzyme CAROTENOID CLEAVAGE DIOXYGENASE8 (CCD8) is present in the moss Physcomitrium patens, and PpCCD8-derived compounds regulate moss extension. The PpMAX2 homolog is not involved in the SL response, but 13 PpKAI2LIKE (PpKAI2L) genes homologous to the D14 ancestral paralog KARRIKIN INSENSITIVE2 (KAI2) encode candidate SL receptors. In Arabidopsis thaliana, AtKAI2 perceives karrikins and the elusive endogenous KAI2-Ligand (KL). Here, germination assays of the parasitic plant Phelipanche ramosa suggested that PpCCD8-derived compounds are likely noncanonical SLs. (+)-GR24 SL analog is a good mimic for PpCCD8-derived compounds in P. patens, while the effects of its enantiomer (-)-GR24, a KL mimic in angiosperms, are minimal. Interaction and binding assays of seven PpKAI2L proteins pointed to the stereoselectivity toward (-)-GR24 for a single clade of PpKAI2L (eu-KAI2). Enzyme assays highlighted the peculiar behavior of PpKAI2L-H. Phenotypic characterization of Ppkai2l mutants showed that eu-KAI2 genes are not involved in the perception of PpCCD8-derived compounds but act in a PpMAX2-dependent pathway. In contrast, mutations in PpKAI2L-G, and -J genes abolished the response to the (+)-GR24 enantiomer, suggesting that PpKAI2L-G, and -J proteins are receptors for moss SLs.
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Affiliation(s)
- Mauricio Lopez-Obando
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université
Paris-Saclay, 78000 Versailles, France
- Department of Plant Biology, Swedish University of Agricultural Sciences, The
Linnean Centre for Plant Biology in Uppsala, SE-750 07 Uppsala, Sweden
- VEDAS Corporación de Investigación e Innovación (VEDASCII),
050024 Medellín, Colombia
| | - Ambre Guillory
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université
Paris-Saclay, 78000 Versailles, France
| | - François-Didier Boyer
- Institut de Chimie des Substances Naturelles, CNRS, Université
Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - David Cornu
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université
Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Beate Hoffmann
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université
Paris-Saclay, 78000 Versailles, France
| | - Philippe Le Bris
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université
Paris-Saclay, 78000 Versailles, France
| | - Jean-Bernard Pouvreau
- Laboratoire de Biologie et Pathologie Végétales, LBPV, Université de
Nantes, 44000 Nantes, France
| | - Philippe Delavault
- Laboratoire de Biologie et Pathologie Végétales, LBPV, Université de
Nantes, 44000 Nantes, France
| | - Catherine Rameau
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université
Paris-Saclay, 78000 Versailles, France
| | - Alexandre de Saint Germain
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université
Paris-Saclay, 78000 Versailles, France
- Author for correspondence:
(S.B.),
(A.d.S.G.)
| | - Sandrine Bonhomme
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université
Paris-Saclay, 78000 Versailles, France
- Author for correspondence:
(S.B.),
(A.d.S.G.)
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19
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Guillory A, Bonhomme S. Phytohormone biosynthesis and signaling pathways of mosses. PLANT MOLECULAR BIOLOGY 2021; 107:245-277. [PMID: 34245404 DOI: 10.1007/s11103-021-01172-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Accepted: 06/30/2021] [Indexed: 06/13/2023]
Abstract
Most known phytohormones regulate moss development. We present a comprehensive view of the synthesis and signaling pathways for the most investigated of these compounds in mosses, focusing on the model Physcomitrium patens. The last 50 years of research have shown that most of the known phytohormones are synthesized by the model moss Physcomitrium patens (formerly Physcomitrella patens) and regulate its development, in interaction with responses to biotic and abiotic stresses. Biosynthesis and signaling pathways are best described in P. patens for the three classical hormones auxins, cytokinins and abscisic acid. Furthermore, their roles in almost all steps of development, from early filament growth to gametophore development and sexual reproduction, have been the focus of much research effort over the years. Evidence of hormonal roles exist for ethylene and for CLE signaling peptides, as well as for salicylic acid, although their possible effects on development remain unclear. Production of brassinosteroids by P. patens is still debated, and modes of action for these compounds are even less known. Gibberellin biosynthesis and signaling may have been lost in P. patens, while gibberellin precursors such as ent-kaurene derivatives could be used as signals in a yet to discover pathway. As for jasmonic acid, it is not used per se as a hormone in P. patens, but its precursor OPDA appears to play a corresponding role in defense against abiotic stress. We have tried to gather a comprehensive view of the biosynthesis and signaling pathways for all these compounds in mosses, without forgetting strigolactones, the last class of plant hormones to be reported. Study of the strigolactone response in P. patens points to a novel signaling compound, the KAI2-ligand, which was likely employed as a hormone prior to land plant emergence.
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Affiliation(s)
- Ambre Guillory
- INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), Université Paris-Saclay, 78000, Versailles, France
| | - Sandrine Bonhomme
- INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), Université Paris-Saclay, 78000, Versailles, France.
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20
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Xu E, Chai L, Zhang S, Yu R, Zhang X, Xu C, Hu Y. Catabolism of strigolactones by a carboxylesterase. NATURE PLANTS 2021; 7:1495-1504. [PMID: 34764442 DOI: 10.1038/s41477-021-01011-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Accepted: 09/18/2021] [Indexed: 06/13/2023]
Abstract
Strigolactones (SLs) are carotenoid-derived plant hormones that control shoot branching and communications between host plants and symbiotic fungi or root parasitic plants. Extensive studies have identified the key components participating in SL biosynthesis and signalling, whereas the catabolism or deactivation of endogenous SLs in planta remains largely unknown. Here, we report that the Arabidopsis carboxylesterase 15 (AtCXE15) and its orthologues function as efficient hydrolases of SLs. We show that overexpression of AtCXE15 promotes shoot branching by dampening SL-inhibited axillary bud outgrowth. We further demonstrate that AtCXE15 could bind and efficiently hydrolyse SLs both in vitro and in planta. We also provide evidence that AtCXE15 is capable of catalysing hydrolysis of diverse SL analogues and that such CXE15-dependent catabolism of SLs is evolutionarily conserved in seed plants. These results disclose a catalytic mechanism underlying homoeostatic regulation of SLs in plants, which also provides a rational approach to spatial-temporally manipulate the endogenous SLs and thus architecture of crops and ornamental plants.
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Affiliation(s)
- Enjun Xu
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Liang Chai
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Shiqi Zhang
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ruixue Yu
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xixi Zhang
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Chongyi Xu
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Yuxin Hu
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
- National Center for Plant Gene Research, Beijing, China.
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21
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Chen J, White A, Nelson DC, Shukla D. Role of substrate recognition in modulating strigolactone receptor selectivity in witchweed. J Biol Chem 2021; 297:101092. [PMID: 34437903 PMCID: PMC8487064 DOI: 10.1016/j.jbc.2021.101092] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 07/26/2021] [Accepted: 08/16/2021] [Indexed: 01/14/2023] Open
Abstract
Witchweed, or Striga hermonthica, is a parasitic weed that destroys billions of dollars' worth of crops globally every year. Its germination is stimulated by strigolactones exuded by its host plants. Despite high sequence, structure, and ligand-binding site conservation across different plant species, one strigolactone receptor in witchweed, ShHTL7, uniquely exhibits a picomolar EC50 for downstream signaling. Previous biochemical and structural analyses have hypothesized that this unique ligand sensitivity can be attributed to a large binding pocket volume in ShHTL7 resulting in enhanced ability to bind substrates, but additional structural details of the substrate-binding process would help explain its role in modulating the ligand selectivity. Using long-timescale molecular dynamics simulations, we demonstrate that mutations at the entrance of the binding pocket facilitate a more direct ligand-binding pathway to ShHTL7, whereas hydrophobicity at the binding pocket entrance results in a stable “anchored” state. We also demonstrate that several residues on the D-loop of AtD14 stabilize catalytically inactive conformations. Finally, we show that strigolactone selectivity is not modulated by binding pocket volume. Our results indicate that while ligand binding is not the sole modulator of strigolactone receptor selectivity, it is a significant contributing factor. These results can be used to inform the design of selective antagonists for strigolactone receptors in witchweed.
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Affiliation(s)
- Jiming Chen
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Alexandra White
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, California, USA
| | - David C Nelson
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, California, USA
| | - Diwakar Shukla
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA; National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA; Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA; NIH Center for Macromolecular Modeling and Bioinformatics, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
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22
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Mizuno Y, Komatsu A, Shimazaki S, Naramoto S, Inoue K, Xie X, Ishizaki K, Kohchi T, Kyozuka J. Major components of the KARRIKIN INSENSITIVE2-dependent signaling pathway are conserved in the liverwort Marchantia polymorpha. THE PLANT CELL 2021; 33:2395-2411. [PMID: 33839776 PMCID: PMC8364241 DOI: 10.1093/plcell/koab106] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 04/06/2021] [Indexed: 05/04/2023]
Abstract
KARRIKIN INSENSITIVE2 (KAI2) was first identified as a receptor of karrikins, smoke-derived germination stimulants. KAI2 is also considered a receptor of an unidentified endogenous molecule called the KAI2 ligand. Upon KAI2 activation, signals are transmitted through the degradation of D53/SMXL proteins via MAX2-dependent ubiquitination. Although components in the KAI2-dependent signaling pathway, namely MpKAI2A and MpKAI2B, MpMAX2, and MpSMXL, exist in the genome of the liverwort Marchantia polymorpha, their functions remain unknown. Here, we show that early thallus growth is retarded and gemma dormancy in the dark is suppressed in Mpkai2a and Mpmax2 loss-of-function mutants. These defects are counteracted in Mpkai2a Mpsmxl and Mpmax2 Mpsmxl double mutants indicating that MpKAI2A, MpMAX2, and MpSMXL act in the same genetic pathway. Introduction of MpSMXLd53, in which a domain required for degradation is mutated, into wild-type plants mimicks Mpkai2a and Mpmax2 plants. In addition, the detection of citrine fluorescence in Nicotiana benthamiana cells transiently expressing a SMXL-Citrine fusion protein requires treatment with MG132, a proteasome inhibitor. These findings imply that MpSMXL is subjected to degradation, and that the degradation of MpSMXL is crucial for MpKAI2A-dependent signaling in M. polymorpha. Therefore, we claim that the basic mechanisms in the KAI2-dependent signaling pathway are conserved in M. polymorpha.
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Affiliation(s)
- Yohei Mizuno
- Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai 980-8577, Japan
| | - Aino Komatsu
- Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai 980-8577, Japan
| | - Shota Shimazaki
- Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai 980-8577, Japan
| | - Satoshi Naramoto
- Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai 980-8577, Japan
| | - Keisuke Inoue
- Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Xiaonan Xie
- Center for Bioscience Research and Education, Utsunomiya University, Tochigi 321-8505, Japan
| | - Kimitsune Ishizaki
- Graduate School of Science, Kobe University, Nada-ku, Kobe 657-8501, Japan
| | - Takayuki Kohchi
- Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Junko Kyozuka
- Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai 980-8577, Japan
- Author for correspondence:
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23
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Three mutations repurpose a plant karrikin receptor to a strigolactone receptor. Proc Natl Acad Sci U S A 2021; 118:2103175118. [PMID: 34301902 DOI: 10.1073/pnas.2103175118] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Uncovering the basis of small-molecule hormone receptors' evolution is paramount to a complete understanding of how protein structure drives function. In plants, hormone receptors for strigolactones are well suited to evolutionary inquiries because closely related homologs have different ligand preferences. More importantly, because of facile plant transgenic systems, receptors can be swapped and quickly assessed functionally in vivo. Here, we show that only three mutations are required to turn the nonstrigolactone receptor, KAI2, into a receptor that recognizes the plant hormone strigolactone. This modified receptor still retains its native function to perceive KAI2 ligands. Our directed evolution studies indicate that only a few keystone mutations are required to increase receptor promiscuity of KAI2, which may have implications for strigolactone receptor evolution in parasitic plants.
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24
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Yao J, Scaffidi A, Meng Y, Melville KT, Komatsu A, Khosla A, Nelson DC, Kyozuka J, Flematti GR, Waters MT. Desmethyl butenolides are optimal ligands for karrikin receptor proteins. THE NEW PHYTOLOGIST 2021; 230:1003-1016. [PMID: 33474738 DOI: 10.1111/nph.17224] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 01/16/2021] [Indexed: 05/25/2023]
Abstract
Strigolactones and karrikins are butenolide molecules that regulate plant growth. They are perceived by the α/β-hydrolase DWARF14 (D14) and its homologue KARRIKIN INSENSITIVE2 (KAI2), respectively. Plant-derived strigolactones have a butenolide ring with a methyl group that is essential for bioactivity. By contrast, karrikins are abiotic in origin, and the butenolide methyl group is nonessential. KAI2 is probably a receptor for an endogenous butenolide, but the identity of this compound remains unknown. Here we characterise the specificity of KAI2 towards differing butenolide ligands using genetic and biochemical approaches. We find that KAI2 proteins from multiple species are most sensitive to desmethyl butenolides that lack a methyl group. Desmethyl-GR24 and desmethyl-CN-debranone are active by KAI2 but not D14. They are more potent KAI2 agonists compared with their methyl-substituted reference compounds both in vitro and in plants. The preference of KAI2 for desmethyl butenolides is conserved in Selaginella moellendorffii and Marchantia polymorpha, suggesting that it is an ancient trait in land plant evolution. Our findings provide insight into the mechanistic basis for differential ligand perception by KAI2 and D14, and support the view that the endogenous substrates for KAI2 and D14 have distinct chemical structures and biosynthetic origins.
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Affiliation(s)
- Jiaren Yao
- School of Molecular Sciences, The University of Western Australia, Perth, WA, 6009, Australia
- ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, Perth, WA, 6009, Australia
| | - Adrian Scaffidi
- School of Molecular Sciences, The University of Western Australia, Perth, WA, 6009, Australia
| | - Yongjie Meng
- School of Molecular Sciences, The University of Western Australia, Perth, WA, 6009, Australia
- ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, Perth, WA, 6009, Australia
| | - Kim T Melville
- School of Molecular Sciences, The University of Western Australia, Perth, WA, 6009, Australia
- ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, Perth, WA, 6009, Australia
| | - Aino Komatsu
- Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan
| | - Aashima Khosla
- Department of Botany and Plant Sciences, University of California, Riverside, CA, 92521, USA
| | - David C Nelson
- Department of Botany and Plant Sciences, University of California, Riverside, CA, 92521, USA
| | - Junko Kyozuka
- Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan
| | - Gavin R Flematti
- School of Molecular Sciences, The University of Western Australia, Perth, WA, 6009, Australia
| | - Mark T Waters
- School of Molecular Sciences, The University of Western Australia, Perth, WA, 6009, Australia
- ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, Perth, WA, 6009, Australia
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25
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Nelson DC. The mechanism of host-induced germination in root parasitic plants. PLANT PHYSIOLOGY 2021; 185:1353-1373. [PMID: 33793958 PMCID: PMC8133615 DOI: 10.1093/plphys/kiab043] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 01/25/2021] [Indexed: 05/25/2023]
Abstract
Chemical signals known as strigolactones (SLs) were discovered more than 50 years ago as host-derived germination stimulants of parasitic plants in the Orobanchaceae. Strigolactone-responsive germination is an essential adaptation of obligate parasites in this family, which depend upon a host for survival. Several species of obligate parasites, including witchweeds (Striga, Alectra spp.) and broomrapes (Orobanche, Phelipanche spp.), are highly destructive agricultural weeds that pose a significant threat to global food security. Understanding how parasites sense SLs and other host-derived stimulants will catalyze the development of innovative chemical and biological control methods. This review synthesizes the recent discoveries of strigolactone receptors in parasitic Orobanchaceae, their signaling mechanism, and key steps in their evolution.
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Affiliation(s)
- David C Nelson
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92521 USA
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26
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Kalia VC, Gong C, Patel SKS, Lee JK. Regulation of Plant Mineral Nutrition by Signal Molecules. Microorganisms 2021; 9:microorganisms9040774. [PMID: 33917219 PMCID: PMC8068062 DOI: 10.3390/microorganisms9040774] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 03/30/2021] [Accepted: 04/03/2021] [Indexed: 01/15/2023] Open
Abstract
Microbes operate their metabolic activities at a unicellular level. However, it has been revealed that a few metabolic activities only prove beneficial to microbes if operated at high cell densities. These cell density-dependent activities termed quorum sensing (QS) operate through specific chemical signals. In Gram-negative bacteria, the most widely reported QS signals are acylhomoserine lactones. In contrast, a novel QS-like system has been elucidated, regulating communication between microbes and plants through strigolactones. These systems regulate bioprocesses, which affect the health of plants, animals, and human beings. This mini-review presents recent developments in the QS and QS-like signal molecules in promoting plant health.
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Affiliation(s)
- Vipin Chandra Kalia
- Department of Chemical Engineering, Konkuk University, Seoul 05029, Korea; (V.C.K.); (S.K.S.P.)
| | - Chunjie Gong
- National “111” Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei University of Technology, Wuhan 430068, China;
| | - Sanjay K. S. Patel
- Department of Chemical Engineering, Konkuk University, Seoul 05029, Korea; (V.C.K.); (S.K.S.P.)
| | - Jung-Kul Lee
- Department of Chemical Engineering, Konkuk University, Seoul 05029, Korea; (V.C.K.); (S.K.S.P.)
- Correspondence:
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27
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Wang NQ, Kong CH, Wang P, Meiners SJ. Root exudate signals in plant-plant interactions. PLANT, CELL & ENVIRONMENT 2021; 44:1044-1058. [PMID: 32931018 DOI: 10.1111/pce.13892] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 08/31/2020] [Accepted: 09/08/2020] [Indexed: 05/12/2023]
Abstract
Plant-to-plant signalling is a key mediator of interactions among plant species. Plants can perceive and respond to chemical cues emitted from their neighbours, altering survival and performance, impacting plant coexistence and community assembly. An increasing number of studies indicate root exudates as key players in plant-to-plant signalling. Root exudates mediate root detection and behaviour, kin recognition, flowering and production, driving inter- and intra-specific facilitation in cropping systems and mixed-species plantations. Altered interactions may be attributed to the signalling components within root exudates. Root ethylene, strigolactones, jasmonic acid, (-)-loliolide and allantoin are signalling chemicals that convey information on local conditions in plant-plant interactions. These root-secreted signalling chemicals appear ubiquitous in plants and trigger a series of belowground responses inter- and intra-specifically, involving molecular events in biosynthesis, secretion and action. The secretion of root signals, mainly mediated by ATP-binding cassette transporters, is critical. Root-secreted signalling chemicals and their molecular mechanisms are rapidly revealing a multitude of fascinating plant-plant interactions. However, many root signals, particularly species-specific signals and their underlying mechanisms, remain to be uncovered due to methodological limitations and root-soil interactions. A thorough understanding of root-secreted chemical signals and their mechanisms will offer many ecological implications and potential applications for sustainable agriculture.
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Affiliation(s)
- Nan-Qi Wang
- College of Resources and Environmental Sciences, China Agricultural University, Beijing, China
| | - Chui-Hua Kong
- College of Resources and Environmental Sciences, China Agricultural University, Beijing, China
| | - Peng Wang
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China
| | - Scott J Meiners
- Department of Biological Sciences, Eastern Illinois University, Charleston, Illinois, USA
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28
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Hamiaux C, Janssen BJ, Snowden KC. The Use of Differential Scanning Fluorimetry to Assess Strigolactone Receptor Function. Methods Mol Biol 2021; 2309:233-243. [PMID: 34028691 DOI: 10.1007/978-1-0716-1429-7_18] [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] [Indexed: 06/12/2023]
Abstract
Differential scanning fluorimetry (DSF) is a method used for assessing the interaction of ligands with proteins. In most cases binding of a ligand to proteins tends to increase the melting temperature (Tm) of the protein involved. However, in the case of strigolactone receptors (e.g., D14, AtD14, DAD2, RMS3) from plants, the Tm tends to be reduced in the presence of strigolactones. This is likely due to increased flexibility of the receptors in the presence of hormone ligands.DSF experiments are simple, fast, amenable to high-throughput formats, and cost effective. They have therefore gained in popularity, including within the field of SL signaling. Typically in DSF the receptor protein is purified and incubated with the ligand (strigolactone, agonist, or antagonist) and a (fluorescent) reporter dye. The mixture is then placed in a quantitative PCR instrument and subjected to an increasing temperature gradient. Changes in fluorescence are recorded along the gradient, as the dye interacts with unfolded portions of the protein becoming accessible when the protein "melts". Differences in the temperature at which the protein unfolds in the absence and in the presence of the ligand are interpreted as indicating interactions between the ligand and the receptor.
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Affiliation(s)
- Cyril Hamiaux
- The New Zealand Institute for Plant & Food Research Limited, Auckland, New Zealand
| | - Bart J Janssen
- The New Zealand Institute for Plant & Food Research Limited, Auckland, New Zealand
| | - Kimberley C Snowden
- The New Zealand Institute for Plant & Food Research Limited, Auckland, New Zealand.
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29
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Aquino B, Bradley JM, Lumba S. On the outside looking in: roles of endogenous and exogenous strigolactones. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 105:322-334. [PMID: 33215770 DOI: 10.1111/tpj.15087] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/27/2020] [Accepted: 10/21/2020] [Indexed: 05/15/2023]
Abstract
A collection of small molecules called strigolactones (SLs) act as both endogenous hormones to control plant development and as ecological communication cues between organisms. SL signalling overlaps with that of a class of smoke-derived compounds, karrikins (KARs), which have distinct yet overlapping developmental effects on plants. Although the roles of SLs in shoot and root development, in the promotion of arbuscular mycorrhizal (AM) fungal branching and in parasitic plant germination have been well characterized, recent data have illustrated broader roles for these compounds in the rhizosphere. Here, we review the known roles of SLs in development, growth of AM fungi and germination of parasitic plants to develop a framework for understanding the use of SLs as molecules of communication in the rhizosphere. It appears, for example, that there are many connections between SLs and phosphate utilization. Low phosphate levels regulate SL metabolism and, in turn, SLs sculpt root and shoot architecture to coordinate growth and optimize phosphate uptake from the environment. Plant-exuded SLs attract fungal symbionts to deliver inorganic phosphate (Pi) to the host. These and other examples suggest the boundary between exogenous and endogenous SL functions can be easily blurred and a more holistic view of these small molecules is likely to be required to fully understand SL biology. Related to this, we summarize and discuss evidence for a primitive role of SLs in moss as a quorum sensing-like molecule, providing a unifying concept of SLs as endogenous and exogenous signalling molecules.
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Affiliation(s)
- Bruno Aquino
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, M5S 3B2, Canada
| | - James M Bradley
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, M5S 3B2, Canada
| | - Shelley Lumba
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, M5S 3B2, Canada
- Centre for the Analysis of Genome Evolution and Function, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
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30
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Carbonnel S, Torabi S, Griesmann M, Bleek E, Tang Y, Buchka S, Basso V, Shindo M, Boyer FD, Wang TL, Udvardi M, Waters MT, Gutjahr C. Lotus japonicus karrikin receptors display divergent ligand-binding specificities and organ-dependent redundancy. PLoS Genet 2020; 16:e1009249. [PMID: 33370251 PMCID: PMC7808659 DOI: 10.1371/journal.pgen.1009249] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 01/14/2021] [Accepted: 11/03/2020] [Indexed: 12/15/2022] Open
Abstract
Karrikins (KARs), smoke-derived butenolides, are perceived by the α/β-fold hydrolase KARRIKIN INSENSITIVE2 (KAI2) and thought to mimic endogenous, yet elusive plant hormones tentatively called KAI2-ligands (KLs). The sensitivity to different karrikin types as well as the number of KAI2 paralogs varies among plant species, suggesting diversification and co-evolution of ligand-receptor relationships. We found that the genomes of legumes, comprising a number of important crops with protein-rich, nutritious seed, contain two or more KAI2 copies. We uncover sub-functionalization of the two KAI2 versions in the model legume Lotus japonicus and demonstrate differences in their ability to bind the synthetic ligand GR24ent-5DS in vitro and in genetic assays with Lotus japonicus and the heterologous Arabidopsis thaliana background. These differences can be explained by the exchange of a widely conserved phenylalanine in the binding pocket of KAI2a with a tryptophan in KAI2b, which arose independently in KAI2 proteins of several unrelated angiosperms. Furthermore, two polymorphic residues in the binding pocket are conserved across a number of legumes and may contribute to ligand binding preferences. The diversification of KAI2 binding pockets suggests the occurrence of several different KLs acting in non-fire following plants, or an escape from possible antagonistic exogenous molecules. Unexpectedly, L. japonicus responds to diverse synthetic KAI2-ligands in an organ-specific manner. Hypocotyl growth responds to KAR1, KAR2 and rac-GR24, while root system development responds only to KAR1. This differential responsiveness cannot be explained by receptor-ligand preferences alone, because LjKAI2a is sufficient for karrikin responses in the hypocotyl, while LjKAI2a and LjKAI2b operate redundantly in roots. Instead, it likely reflects differences between plant organs in their ability to transport or metabolise the synthetic KLs. Our findings provide new insights into the evolution and diversity of butenolide ligand-receptor relationships, and open novel research avenues into their ecological significance and the mechanisms controlling developmental responses to divergent KLs.
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Affiliation(s)
- Samy Carbonnel
- LMU Munich, Faculty of Biology, Genetics, Biocenter Martinsried, Martinsried, Germany
- Technical University of Munich (TUM), TUM School of Life Sciences, Plant Genetics, Freising, Germany
| | - Salar Torabi
- LMU Munich, Faculty of Biology, Genetics, Biocenter Martinsried, Martinsried, Germany
- Technical University of Munich (TUM), TUM School of Life Sciences, Plant Genetics, Freising, Germany
| | - Maximilian Griesmann
- LMU Munich, Faculty of Biology, Genetics, Biocenter Martinsried, Martinsried, Germany
| | - Elias Bleek
- LMU Munich, Faculty of Biology, Genetics, Biocenter Martinsried, Martinsried, Germany
| | - Yuhong Tang
- Noble Research Institute, Ardmore, Oklahoma, United States of America
| | - Stefan Buchka
- LMU Munich, Faculty of Biology, Genetics, Biocenter Martinsried, Martinsried, Germany
| | - Veronica Basso
- LMU Munich, Faculty of Biology, Genetics, Biocenter Martinsried, Martinsried, Germany
| | - Mitsuru Shindo
- Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka, Japan
| | - François-Didier Boyer
- Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, Gif-sur-Yvette, France
| | - Trevor L. Wang
- John Innes Centre, Norwich Research Park, Norwich, United Kingdom
| | - Michael Udvardi
- Noble Research Institute, Ardmore, Oklahoma, United States of America
| | - Mark T. Waters
- School of Molecular Sciences, The University of Western Australia, Perth, Australia
- Australian Research Council Centre of Excellence in Plant Energy Biology, The University of Western Australia, Perth, Australia
| | - Caroline Gutjahr
- LMU Munich, Faculty of Biology, Genetics, Biocenter Martinsried, Martinsried, Germany
- Technical University of Munich (TUM), TUM School of Life Sciences, Plant Genetics, Freising, Germany
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31
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Nakajima M, Miyazaki S, Kawaide H. Hormonal Diterpenoids Distinct to Gibberellins Regulate Protonema Differentiation in the Moss Physcomitrium patens. ACTA ACUST UNITED AC 2020; 61:1861-1868. [DOI: 10.1093/pcp/pcaa129] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 09/30/2020] [Indexed: 01/14/2023]
Abstract
Abstract
Plants synthesize gibberellin (GA), a diterpenoid hormone, via ent-kaurenoic acid (KA) oxidation. GA has not been detected in the moss Physcomitrium patens despite its ability to synthesize KA. It was recently shown that a KA metabolite, 3OH-KA, was identified as an active regulator of protonema differentiation in P. patens. An inactive KA metabolite, 2OH-KA, was also identified in the moss, as was KA2ox, which is responsible for converting KA to 2OH-KA. In this review, we mainly discuss the GA biosynthetic gene homologs identified and characterized in bryophytes. We show the similarities and differences between the OH-KA control of moss and GA control of flowering plants. We also discuss using recent genomic studies; mosses do not contain KAO, even though other bryophytes do. This absence of KAO in mosses corresponds to the presence of KA2ox, which is absent in other vascular plants. Thus, given that 2OH-KA and 3OH-KA were isolated from ferns and flowering plants, respectively, vascular plants may have evolved from ancestral bryophytes that originally produced 3OH-KA and GA.
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Affiliation(s)
- Masatoshi Nakajima
- Department of Applied Biological Chemistry, The University of Tokyo, Tokyo, 113-8657 Japan
| | - Sho Miyazaki
- Faculty of Science and Technology, Keio University, Yokohama, 223-8522 Japan
| | - Hiroshi Kawaide
- Institute of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, 183-8509 Japan
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32
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Bürger M, Chory J. In-silico analysis of the strigolactone ligand-receptor system. PLANT DIRECT 2020; 4:e00263. [PMID: 32995702 PMCID: PMC7507525 DOI: 10.1002/pld3.263] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 07/31/2020] [Accepted: 08/08/2020] [Indexed: 05/17/2023]
Abstract
Strigolactones (SLs) are a diverse class of butenolide-bearing plant hormones associated with several processes of major agricultural concern. SLs initiate symbiosis between plants and arbuscular mycorrhizal fungi, cause germination of crop-devastating parasitic plants, and inhibit shoot branching in vascular plants. SLs are perceived by dual receptor-hydrolase proteins, and capturing the intact ligand inside the receptor remains a key challenge for structural biologists. In addition, many discovered SLs are hard to obtain and too unstable to work with. In a computer-based approach, we investigated the interaction of 20 different SL molecules with nine crystal structures of SL receptors. Our results suggest an important role of the active site for ligand binding and orientation, and that the parasitic plant Striga hermonthica has developed both promiscuous and type-specific SL receptors as part of its host recognition strategy.
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Affiliation(s)
- Marco Bürger
- Plant Biology LaboratorySalk Institute for Biological StudiesLa JollaCAUSA
| | - Joanne Chory
- Plant Biology LaboratorySalk Institute for Biological StudiesLa JollaCAUSA
- Howard Hughes Medical InstituteSalk Institute for Biological StudiesLa JollaCAUSA
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33
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Zheng J, Hong K, Zeng L, Wang L, Kang S, Qu M, Dai J, Zou L, Zhu L, Tang Z, Meng X, Wang B, Hu J, Zeng D, Zhao Y, Cui P, Wang Q, Qian Q, Wang Y, Li J, Xiong G. Karrikin Signaling Acts Parallel to and Additively with Strigolactone Signaling to Regulate Rice Mesocotyl Elongation in Darkness. THE PLANT CELL 2020; 32:2780-2805. [PMID: 32665307 PMCID: PMC7474294 DOI: 10.1105/tpc.20.00123] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 06/02/2020] [Accepted: 07/09/2020] [Indexed: 05/18/2023]
Abstract
Seedling emergence in monocots depends mainly on mesocotyl elongation, requiring coordination between developmental signals and environmental stimuli. Strigolactones (SLs) and karrikins are butenolide compounds that regulate various developmental processes; both are able to negatively regulate rice (Oryza sativa) mesocotyl elongation in the dark. Here, we report that a karrikin signaling complex, DWARF14-LIKE (D14L)-DWARF3 (D3)-O. sativa SUPPRESSOR OF MAX2 1 (OsSMAX1) mediates the regulation of rice mesocotyl elongation in the dark. We demonstrate that D14L recognizes the karrikin signal and recruits the SCFD3 ubiquitin ligase for the ubiquitination and degradation of OsSMAX1, mirroring the SL-induced and D14- and D3-dependent ubiquitination and degradation of D53. Overexpression of OsSMAX1 promoted mesocotyl elongation in the dark, whereas knockout of OsSMAX1 suppressed the elongated-mesocotyl phenotypes of d14l and d3 OsSMAX1 localizes to the nucleus and interacts with TOPLESS-RELATED PROTEINs, regulating downstream gene expression. Moreover, we showed that the GR24 enantiomers GR245DS and GR24 ent-5DS specifically inhibit mesocotyl elongation and regulate downstream gene expression in a D14- and D14L-dependent manner, respectively. Our work revealed that karrikin and SL signaling play parallel and additive roles in modulating downstream gene expression and negatively regulating mesocotyl elongation in the dark.
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Affiliation(s)
- Jianshu Zheng
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Kai Hong
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Longjun Zeng
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
- Plant Phenomics Research Center, Nanjing Agricultural University, Nanjing, 210095, China
| | - Lei Wang
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Shujing Kang
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
- College of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Minghao Qu
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Jiarong Dai
- Plant Phenomics Research Center, Nanjing Agricultural University, Nanjing, 210095, China
- College of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China
| | - Linyuan Zou
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Lixin Zhu
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310006, China
| | - Zhanpeng Tang
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Xiangbing Meng
- State Key Laboratory of Plant Genomics, and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Bing Wang
- State Key Laboratory of Plant Genomics, and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Jiang Hu
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310006, China
| | - Dali Zeng
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310006, China
| | - Yonghui Zhao
- Plant Phenomics Research Center, Nanjing Agricultural University, Nanjing, 210095, China
| | - Peng Cui
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Quan Wang
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Qian Qian
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310006, China
| | - Yonghong Wang
- State Key Laboratory of Plant Genomics, and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100039, China
- College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
| | - Jiayang Li
- State Key Laboratory of Plant Genomics, and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100039, China
| | - Guosheng Xiong
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
- Plant Phenomics Research Center, Nanjing Agricultural University, Nanjing, 210095, China
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The karrikin signaling regulator SMAX1 controls Lotus japonicus root and root hair development by suppressing ethylene biosynthesis. Proc Natl Acad Sci U S A 2020; 117:21757-21765. [PMID: 32817510 DOI: 10.1073/pnas.2006111117] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
An evolutionarily ancient plant hormone receptor complex comprising the α/β-fold hydrolase receptor KARRIKIN INSENSITIVE 2 (KAI2) and the F-box protein MORE AXILLARY GROWTH 2 (MAX2) mediates a range of developmental responses to smoke-derived butenolides called karrikins (KARs) and to yet elusive endogenous KAI2 ligands (KLs). Degradation of SUPPRESSOR OF MAX2 1 (SMAX1) after ligand perception is considered to be a key step in KAR/KL signaling. However, molecular events which regulate plant development downstream of SMAX1 removal have not been identified. Here we show that Lotus japonicus SMAX1 is specifically degraded in the presence of KAI2 and MAX2 and plays an important role in regulating root and root hair development. smax1 mutants display very short primary roots and elongated root hairs. Their root transcriptome reveals elevated ethylene responses and expression of ACC Synthase 7 (ACS7), which encodes a rate-limiting enzyme in ethylene biosynthesis. smax1 mutants release increased amounts of ethylene and their root phenotype is rescued by treatment with ethylene biosynthesis and signaling inhibitors. KAR treatment induces ACS7 expression in a KAI2-dependent manner and root developmental responses to KAR treatment depend on ethylene signaling. Furthermore, in Arabidopsis, KAR-induced root hair elongation depends on ACS7 Thus, we reveal a connection between KAR/KL and ethylene signaling in which the KAR/KL signaling module (KAI2-MAX2-SMAX1) regulates the biosynthesis of ethylene to fine-tune root and root hair development, which are important for seedling establishment at the beginning of the plant life cycle.
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Khosla A, Morffy N, Li Q, Faure L, Chang SH, Yao J, Zheng J, Cai ML, Stanga J, Flematti GR, Waters MT, Nelson DC. Structure-Function Analysis of SMAX1 Reveals Domains That Mediate Its Karrikin-Induced Proteolysis and Interaction with the Receptor KAI2. THE PLANT CELL 2020; 32:2639-2659. [PMID: 32434855 PMCID: PMC7401016 DOI: 10.1105/tpc.19.00752] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 04/13/2020] [Accepted: 05/14/2020] [Indexed: 05/18/2023]
Abstract
Karrikins (KARs) are butenolides found in smoke that can influence germination and seedling development of many plants. The KAR signaling mechanism is hypothesized to be very similar to that of the plant hormone strigolactone (SL). Both pathways require the F-box protein MORE AXILLARY GROWTH2 (MAX2), and other core signaling components have shared ancestry. Putatively, KAR activates the receptor KARRIKIN INSENSITIVE2 (KAI2), triggering its association with the E3 ubiquitin ligase complex SCFMAX2 and downstream targets SUPPRESSOR OF MAX2 1 (SMAX1) and SMAX1-LIKE2 (SMXL2). Polyubiquitination and proteolysis of SMAX1 and SMXL2 then enable growth responses to KAR. However, many of the assumptions of this model have not been demonstrated. Therefore, we investigated the posttranslational regulation of SMAX1 from the model plant Arabidopsis (Arabidopsis thaliana). We find evidence that SMAX1 is degraded by KAI2-SCFMAX2 but is also subject to MAX2-independent turnover. We identify SMAX1 domains that are responsible for its nuclear localization, KAR-induced degradation, association with KAI2, and ability to interact with other SMXL proteins. KAI2 undergoes MAX2-independent degradation after KAR treatment, which we propose results from its association with SMAX1 and SMXL2. Finally, we discover an SMXL domain that mediates receptor-target interaction preferences in KAR and SL signaling, laying the foundation for understanding how these highly similar pathways evolved to fulfill different roles.
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Affiliation(s)
- Aashima Khosla
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521
| | - Nicholas Morffy
- Department of Genetics, University of Georgia, Athens, Georgia 30602
| | - Qingtian Li
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521
| | - Lionel Faure
- Department of Genetics, University of Georgia, Athens, Georgia 30602
- Department of Biology, Texas Woman's University, Denton, Texas 76204
| | - Sun Hyun Chang
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521
| | - Jiaren Yao
- School of Molecular Sciences, University of Western Australia Perth, Crawley, Western Australia 6009, Australia
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia Perth, Crawley, Western Australia 6009, Australia
| | - Jiameng Zheng
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521
| | - Mei L Cai
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521
| | - John Stanga
- Department of Genetics, University of Georgia, Athens, Georgia 30602
- Department of Biology, Mercer University, Macon, Georgia 31207
| | - Gavin R Flematti
- School of Molecular Sciences, University of Western Australia Perth, Crawley, Western Australia 6009, Australia
| | - Mark T Waters
- School of Molecular Sciences, University of Western Australia Perth, Crawley, Western Australia 6009, Australia
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia Perth, Crawley, Western Australia 6009, Australia
| | - David C Nelson
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521
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Abstract
This review focuses on the evolution of plant hormone signaling pathways. Like the chemical nature of the hormones themselves, the signaling pathways are diverse. Therefore, we focus on a group of hormones whose primary perception mechanism involves an Skp1/Cullin/F-box-type ubiquitin ligase: auxin, jasmonic acid, gibberellic acid, and strigolactone. We begin with a comparison of the core signaling pathways of these four hormones, which have been established through studies conducted in model organisms in the Angiosperms. With the advent of next-generation sequencing and advanced tools for genetic manipulation, the door to understanding the origins of hormone signaling mechanisms in plants beyond these few model systems has opened. For example, in-depth phylogenetic analyses of hormone signaling components are now being complemented by genetic studies in early diverging land plants. Here we discuss recent investigations of how basal land plants make and sense hormones. Finally, we propose connections between the emergence of hormone signaling complexity and major developmental transitions in plant evolution.
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Affiliation(s)
- Miguel A Blázquez
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, 46022 Valencia, Spain;
| | - David C Nelson
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521, USA;
| | - Dolf Weijers
- Laboratory of Biochemistry, Wageningen University, 6708WE Wageningen, The Netherlands;
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Tal L, Gil MXA, Guercio AM, Shabek N. Structural Aspects of Plant Hormone Signal Perception and Regulation by Ubiquitin Ligases. PLANT PHYSIOLOGY 2020; 182:1537-1544. [PMID: 31919187 PMCID: PMC7140925 DOI: 10.1104/pp.19.01282] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 12/05/2019] [Indexed: 05/07/2023]
Abstract
Hormonal cues regulate many aspects of plant growth and development, facilitating the plant's ability to systemically respond to environmental changes. Elucidating the molecular mechanisms governing these signaling pathways is crucial to understanding how plants function. Structural and functional biology methods have been essential in decoding plant genetic findings and revealing precise molecular actions at the protein level. Past studies of plant hormone signaling have uncovered mechanisms that involve highly coordinated protein turnover to elicit immediate cellular responses. Many phytohormone signaling pathways rely on the ubiquitin (Ub) proteasome system, specifically E3 Ub ligases, for perception and initiation of signaling transduction. In this review, we highlight structural aspects of plant hormone-sensing mechanisms by Ub ligases and discuss our current understanding of the emerging field of strigolactone signaling.
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Affiliation(s)
- Lior Tal
- Department of Plant Biology, University of California Davis, Davis, California 95616
| | - M Ximena Anleu Gil
- Department of Plant Biology, University of California Davis, Davis, California 95616
| | - Angelica M Guercio
- Department of Plant Biology, University of California Davis, Davis, California 95616
| | - Nitzan Shabek
- Department of Plant Biology, University of California Davis, Davis, California 95616
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Bürger M, Chory J. The Many Models of Strigolactone Signaling. TRENDS IN PLANT SCIENCE 2020; 25:395-405. [PMID: 31948791 PMCID: PMC7184880 DOI: 10.1016/j.tplants.2019.12.009] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 11/23/2019] [Accepted: 12/09/2019] [Indexed: 05/20/2023]
Abstract
Strigolactones (SLs) are a class of plant hormones involved in several biological processes that are of great agricultural concern. While initiating plant-fungal symbiosis, SLs also trigger germination of parasitic plants that pose a major threat to farming. In vascular plants, SLs control shoot branching, which is linked to crop yield. SL research has been a fascinating field that has produced a variety of different signaling models, reflecting a complex picture of hormone perception. Here, we review recent developments in the SL field and the crystal structures that gave rise to various models of receptor activation. We also highlight the increasing number of discovered SL molecules, reflecting the existence of cross-kingdom SL communication.
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Affiliation(s)
- Marco Bürger
- Plant Biology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
| | - Joanne Chory
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
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Yao J, Waters MT. Perception of karrikins by plants: a continuing enigma. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:1774-1781. [PMID: 31836893 PMCID: PMC7242065 DOI: 10.1093/jxb/erz548] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 12/09/2019] [Indexed: 05/28/2023]
Abstract
Karrikins are small butenolide molecules with the capacity to promote germination and enhance seedling establishment. Generated abiotically from partial combustion of vegetation, karrikins are comparatively rare in the environment, but studying their mode of action has been most informative in revealing a new regulatory pathway for plant development that uses the karrikin perception machinery. Recent studies suggest that the karrikin receptor protein KAI2 and downstream transcriptional co-repressors in the SMXL family influence seed germination, seedling photomorphogenesis, root morphology, and responses to abiotic stress such as drought. Based on taxonomic distribution, this pathway is ubiquitous and likely to be evolutionarily ancient, originating prior to land plants. However, we still do not have a good grasp on how karrikins actually activate the receptor protein, and we have yet to discover the assumed endogenous ligand for KAI2 that karrikins are thought to mimic. This review covers recent progress in this field, as well as current gaps in our knowledge.
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Affiliation(s)
- Jiaren Yao
- School of Molecular Sciences, The University of Western Australia, Perth, WA, Australia
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Divergent receptor proteins confer responses to different karrikins in two ephemeral weeds. Nat Commun 2020; 11:1264. [PMID: 32152287 PMCID: PMC7062792 DOI: 10.1038/s41467-020-14991-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 02/12/2020] [Indexed: 11/08/2022] Open
Abstract
Wildfires can encourage the establishment of invasive plants by releasing potent germination stimulants, such as karrikins. Seed germination of Brassica tournefortii, a noxious weed of Mediterranean climates, is strongly stimulated by KAR1, the archetypal karrikin produced from burning vegetation. In contrast, the closely-related yet non-fire-associated ephemeral Arabidopsisthaliana is unusual because it responds preferentially to KAR2. The α/β-hydrolase KARRIKIN INSENSITIVE 2 (KAI2) is the putative karrikin receptor identified in Arabidopsis. Here we show that B. tournefortii expresses three KAI2 homologues, and the most highly-expressed homologue is sufficient to confer enhanced responses to KAR1 relative to KAR2 when expressed in Arabidopsis. We identify two amino acid residues near the KAI2 active site that explain the ligand selectivity, and show that this combination has arisen independently multiple times within dicots. Our results suggest that duplication and diversification of KAI2 proteins could confer differential responses to chemical cues produced by environmental disturbance, including fire. Karrikins are germination stimulants perceived by KAI2 in Arabidopsis. Here the authors show that Brassica tournefortii, a close relative to Arabidopsis, has multiple copies of KAI2 with amino acid substitutions that confer responsiveness to the specific karrikin compounds found in wildfire smoke.
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Zhang Y, Wang D, Shen Y, Xi Z. Crystal structure and biochemical characterization of Striga hermonthica HYPO-SENSITIVE TO LIGHT 8 (ShHTL8) in strigolactone signaling pathway. Biochem Biophys Res Commun 2020; 523:1040-1045. [PMID: 31973817 DOI: 10.1016/j.bbrc.2020.01.056] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 01/11/2020] [Indexed: 01/06/2023]
Abstract
Striga is a parasitic weed that disperses easily, and its seeds can persist in the soil for many years, presenting long-term threats to food security. If SLs stimulate the seed germination of root parasitic weeds before planting, weeds will wither due to no host. Therefore, it is necessary to determine the mechanism of strigolactone (SL) signaling in Striga to reduce the impacts of this parasitic weed. Striga has eleven different kinds of HYPO-SENSITIVE to LIGHT (ShHTL) hydrolases. Different ShHTL hydrolases exhibit distinct responses to SLs, despite these ShHTLs exhibiting more than 60% sequence identity. Currently, structural information is available for only five ShHTL proteins, and more structural information is needed to design Striga germination stimulants or inhibitors. In this paper, we report the crystal structure of ShHTL8, which is determined at a resolution of 1.4 Å. Scanning fluorimetry and HPLC assays indicate that L125, M147, M154 and I194 are important binding sites, and of which L125 may act as a key holder involved in the catalytic reaction. Additionally, the corresponding residue, Y124 of ShHTL1 and F135 of ShHTL2 also play a significant role in the substrate recognition.
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Affiliation(s)
- Yingying Zhang
- State Key Laboratory of Elemento-Organic Chemistry and College of Chemistry Nankai University, Weijin 94, Tianjin, 300071, China
| | - Dawei Wang
- State Key Laboratory of Elemento-Organic Chemistry and College of Chemistry Nankai University, Weijin 94, Tianjin, 300071, China
| | - Yuequan Shen
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, Tianjin, 300353, China.
| | - Zhen Xi
- State Key Laboratory of Elemento-Organic Chemistry and College of Chemistry Nankai University, Weijin 94, Tianjin, 300071, China.
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Machin DC, Hamon-Josse M, Bennett T. Fellowship of the rings: a saga of strigolactones and other small signals. THE NEW PHYTOLOGIST 2020; 225:621-636. [PMID: 31442309 DOI: 10.1111/nph.16135] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Accepted: 08/08/2019] [Indexed: 05/25/2023]
Abstract
Strigolactones are an important class of plant signalling molecule with both external rhizospheric and internal hormonal functions in flowering plants. The past decade has seen staggering progress in strigolactone biology, permitting highly detailed understanding of their signalling, synthesis and biological roles - or so it seems. However, phylogenetic analyses show that strigolactone signalling mediated by the D14-SCFMAX2 -SMXL7 complex is only one of a number of closely related signalling pathways, and is much less ubiquitous in land plants than might be expected. The existence of closely related pathways, such as the KAI2-SMAX1 module, challenges many of our assumptions about strigolactones, and in particular emphasises how little we understand about the specificity of strigolactone signalling with respect to related signalling pathways. In this review, we examine recent advances in strigolactone signalling, taking a holistic evolutionary view to identify the ambiguities and uncertainties in our understanding. We highlight that while we now have highly detailed molecular models for the core mechanism of D14-SMXL7 signalling, we still do not understand the ligand specificity of D14, the specificity of its interaction with SMXL7, nor the specificity of SMXL7 function. Our analysis therefore identifies key areas requiring further study.
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Affiliation(s)
- Darren C Machin
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Maxime Hamon-Josse
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Tom Bennett
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
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Takaoka Y, Hayashi K, Suzuki K, Azizah IN, Ueda M. A Fluorescence Anisotropy-Based Comprehensive Method for the In Vitro Screening of COI1-JAZs Agonists and Antagonists. Methods Mol Biol 2020; 2085:145-160. [PMID: 31734923 DOI: 10.1007/978-1-0716-0142-6_11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The phytohormone (+)-7-iso-jasmonoyl-L-isoleucine (JA-Ile) causes protein-protein interactions (PPI) between F-box Protein CORONATINE INSENSITIVE 1 (COI1) and JASMONATE ZIM DOMAIN (JAZ) transcriptional repressor. A total of 13 JAZ subtypes are encoded in the genome of Arabidopsis thaliana; however, their genetic redundancy obfuscates the individual function of each JAZ. One approach to decipher this redundant signaling network is chemical genetics, using small molecules specific to individual JAZ subtype, for which a reliable and high-throughput screening system of the ligands for all combinations of COI1-JAZs would be indispensable. In this chapter, we describe a fluorescence anisotropy-based quantitative screening system for the ligands of COI1-JAZ co-receptors. Our method is applicable to agonists and antagonists of the COI1-JAZs.
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Affiliation(s)
- Yousuke Takaoka
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan
- Precursory Research for Embryonic Science and Technology (PREST), Japan Science and Technology Agency, Tokyo, Japan
| | - Kengo Hayashi
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan
| | - Kaho Suzuki
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan
| | - Ika Nurul Azizah
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan
| | - Minoru Ueda
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, Japan.
- Department of Molecular and Chemical Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan.
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Walker CH, Siu-Ting K, Taylor A, O'Connell MJ, Bennett T. Strigolactone synthesis is ancestral in land plants, but canonical strigolactone signalling is a flowering plant innovation. BMC Biol 2019; 17:70. [PMID: 31488154 PMCID: PMC6728956 DOI: 10.1186/s12915-019-0689-6] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 08/13/2019] [Indexed: 11/10/2022] Open
Abstract
Background Strigolactones (SLs) are an important class of carotenoid-derived signalling molecule in plants, which function both as exogenous signals in the rhizosphere and as endogenous plant hormones. In flowering plants, SLs are synthesized by a core pathway of four enzymes and are perceived by the DWARF14 (D14) receptor, leading to degradation of SMAX1-LIKE7 (SMXL7) target proteins in a manner dependent on the SCFMAX2 ubiquitin ligase. The evolutionary history of SLs is poorly understood, and it is not clear whether SL synthesis and signalling are present in all land plant lineages, nor when these traits evolved. Results We have utilized recently-generated genomic and transcriptomic sequences from across the land plant clade to resolve the origin of each known component of SL synthesis and signalling. We show that all enzymes in the core SL synthesis pathway originated at or before the base of land plants, consistent with the previously observed distribution of SLs themselves in land plant lineages. We also show that the late-acting enzyme LATERAL BRANCHING OXIDOREDUCTASE (LBO) may be considerably more ancient than previously thought. We perform a detailed phylogenetic analysis of SMXL proteins and show that specific SL target proteins only arose in flowering plants. We also assess diversity and protein structure in the SMXL family, identifying several previously unknown clades. Conclusions Overall, our results suggest that SL synthesis is much more ancient than canonical SL signalling, consistent with the idea that SLs first evolved as rhizosphere signals and were only recruited much later as hormonal signals. Electronic supplementary material The online version of this article (10.1186/s12915-019-0689-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Catriona H Walker
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Karen Siu-Ting
- Institute for Global Food Security, School of Biological Sciences, Queens University, Belfast, BT7 1NN, UK.,Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, SY23 3FD, UK
| | - Alysha Taylor
- Computational and Molecular Evolutionary Biology Research Group, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Mary J O'Connell
- Computational and Molecular Evolutionary Biology Research Group, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK.,Computational and Molecular Evolutionary Biology Research Group, School of Life Sciences, Faculty of Medicine and Health Sciences, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Tom Bennett
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK.
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