1
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Karami O, de Jong H, Somovilla VJ, Villanueva Acosta B, Sugiarta AB, Ham M, Khadem A, Wennekes T, Offringa R. Structure-activity relationship of 2,4-D correlates auxinic activity with the induction of somatic embryogenesis in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 116:1355-1369. [PMID: 37647363 DOI: 10.1111/tpj.16430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 07/19/2023] [Accepted: 08/04/2023] [Indexed: 09/01/2023]
Abstract
2,4-dichlorophenoxyacetic acid (2,4-D) is a synthetic analogue of the plant hormone auxin that is commonly used in many in vitro plant regeneration systems, such as somatic embryogenesis (SE). Its effectiveness in inducing SE, compared to the natural auxin indole-3-acetic acid (IAA), has been attributed to the stress triggered by this compound rather than its auxinic activity. However, this hypothesis has never been thoroughly tested. Here we used a library of forty 2,4-D analogues to test the structure-activity relationship with respect to the capacity to induce SE and auxinic activity in Arabidopsis thaliana. Four analogues induced SE as effectively as 2,4-D and 13 analogues induced SE but were less effective. Based on root growth inhibition and auxin response reporter expression, the 2,4-D analogues were classified into different groups, ranging from very active to not active auxin analogues. A halogen at the 4-position of the aromatic ring was important for auxinic activity, whereas a halogen at the 3-position resulted in reduced activity. Moreover, a small substitution at the carboxylate chain was tolerated, as was extending the carboxylate chain with an even number of carbons. The auxinic activity of most 2,4-D analogues was consistent with their simulated TIR1-Aux/IAA coreceptor binding characteristics. A strong correlation was observed between SE induction efficiency and auxinic activity, which is in line with our observation that 2,4-D-induced SE and stress both require TIR1/AFB auxin co-receptor function. Our data indicate that the stress-related effects triggered by 2,4-D and considered important for SE induction are downstream of auxin signalling.
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Affiliation(s)
- Omid Karami
- Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE, Leiden, Netherlands
| | - Hanna de Jong
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences and Bijvoet Center for Biomedical Research, Utrecht University, Universiteitsweg 99, 3584CG, Utrecht, The Netherlands
| | - Victor J Somovilla
- Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA), Paseo de Miramon 182, 20014, Donostia San Sebastián, Spain
| | - Beatriz Villanueva Acosta
- Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE, Leiden, Netherlands
| | - Aldo Bryan Sugiarta
- Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE, Leiden, Netherlands
| | - Marvin Ham
- Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE, Leiden, Netherlands
| | - Azadeh Khadem
- Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE, Leiden, Netherlands
| | - Tom Wennekes
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences and Bijvoet Center for Biomedical Research, Utrecht University, Universiteitsweg 99, 3584CG, Utrecht, The Netherlands
| | - Remko Offringa
- Plant Developmental Genetics, Institute of Biology Leiden, Leiden University, Sylviusweg 72, 2333 BE, Leiden, Netherlands
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2
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Kalyuta EV, Maltsev MI, Markin VI, Mashkina EI. Effect of Biopreparations Obtained from Carboxymethylated Plant Raw Material on the Wheat Growth, Crop Capacity, and Biochemical Parameters of Grain. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2022. [DOI: 10.1134/s1068162022070081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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3
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Cho M, Kim K. Diclofenac modified the root system architecture of Arabidopsis via interfering with the hormonal activities of auxin. JOURNAL OF HAZARDOUS MATERIALS 2021; 413:125402. [PMID: 33626476 DOI: 10.1016/j.jhazmat.2021.125402] [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: 08/20/2020] [Revised: 01/20/2021] [Accepted: 02/09/2021] [Indexed: 06/12/2023]
Abstract
Diclofenac, a pharmaceutical and personal care product, is accumulating in various environmental matrices worldwide. Increased irrigation has facilitated an influx of environmental diclofenac into agricultural products, which potentially threatens non-target living organisms. In this study, we demonstrated that diclofenac modified the growth and root developmental processes of plants by disturbing the activity of auxin, a group of major phytohormones. Exogenous diclofenac treatment retarded growth and induced oxidative stress in young seedlings of Arabidopsis thaliana. In the developmental perspective, diclofenac altered the root system architecture, which was also similarly observed under exogenous IAA (a natural form of phytoalexins) treatment. The effects of diclofenac on the root development of A. thaliana were mediated through canonical auxin signaling pathways. However, when diclofenac and IAA were treated in combination, diclofenac suppressed the activity of IAA in root system architecture. At the molecular level, diclofenac significantly inhibited the activity of IAA upregulating the expression of early auxin-responsive marker genes. In conclusion, diclofenac modified the root development of A. thaliana via interfering with the activities of natural auxin. These results indicate that diclofenac could potentially act as an environmental contaminant disturbing the natural developmental processes of plants.
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Affiliation(s)
- Min Cho
- SELS Center, Division of Biotechnology, College of Bioresources and Environmental Science, Chonbuk National University, Iksan 54596, Republic of Korea
| | - Kangmin Kim
- SELS Center, Division of Biotechnology, College of Bioresources and Environmental Science, Chonbuk National University, Iksan 54596, Republic of Korea.
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4
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Abstract
Molecular genetic and structural studies have revealed the mechanisms of fundamental components of key auxin regulatory pathways consisting of auxin biosynthesis, transport, and signaling. Chemical biology methods applied in auxin research have been greatly expanded through the understanding of auxin regulatory pathways. Many small-molecule modulators of auxin metabolism, transport, and signaling have been generated on the basis of the outcomes of genetic and structural studies on auxin regulatory pathways. These chemical modulators are now widely used as essential tools for dissecting auxin biology in diverse plants. This review covers the structures, primary targets, modes of action, and applications of chemical tools in auxin biosynthesis, transport, and signaling.
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Affiliation(s)
- Ken-Ichiro Hayashi
- Department of Biochemistry, Okayama University of Science, Okayama City 700-0005, Japan
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5
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Torii KU, Hagihara S, Uchida N, Takahashi K. Harnessing synthetic chemistry to probe and hijack auxin signaling. THE NEW PHYTOLOGIST 2018; 220:417-424. [PMID: 30088268 DOI: 10.1111/nph.15337] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 05/24/2018] [Indexed: 06/08/2023]
Abstract
Contents Summary 417 I. Introduction 417 II. Auxin analogs 1: Plant growth regulators 418 III. Auxin analogs 2: Molecular genetics and chemical biology 418 IV. Auxin analogs 3: Structure-guided chemical design 418 V. Auxin analogs 4: Synthetic orthogonal auxin-TIR1 pair 420 VI. Conclusions and future perspectives 422 Acknowledgements 422 References 423 SUMMARY: Plant biologists have been fascinated by auxin - a small chemical hormone so simple in structure yet so powerful - which regulates virtually every aspect of plant growth, development and behavior. Synthetic chemistry has played a major role in unraveling the physiological effects of auxin and the application of synthetic analogs has had a dramatic effect on tissue culture, horticulture and the agriculture of economically relevant plant species. Chemical genetics of the model plant, Arabidopsis thaliana, has helped to elucidate the nuclear auxin signaling pathway mediated by the receptor, TIR1, and opened the door to structure-guided, rational designs of auxin agonists and antagonists. Further improvement and tuning of such analogs has been achieved through derivatization and screening. Finally, by harnessing synthetic chemistry and receptor engineering, an orthogonal auxin-TIR1 pair has been created and developed, enabling spatiotemporal control of auxin perception and response. This synergism of chemistry, biology and engineering sparks new ideas and directions to delineate, uncover and manipulate auxin signaling.
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Affiliation(s)
- Keiko U Torii
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, 98195, USA
- Department of Biology, University of Washington, Seattle, WA, 98195, USA
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya, 464-8601, Japan
- Graduate School of Science, Nagoya University, Chikusa, Nagoya, 464-8602, Japan
| | - Shinya Hagihara
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya, 464-8601, Japan
- Graduate School of Science, Nagoya University, Chikusa, Nagoya, 464-8602, Japan
- RIKEN Center for Sustainable Resource Science (CSRS), Wako, Saitama, 351-0198, Japan
- PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, 332-0012, Japan
| | - Naoyuki Uchida
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya, 464-8601, Japan
- Graduate School of Science, Nagoya University, Chikusa, Nagoya, 464-8602, Japan
| | - Koji Takahashi
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Chikusa, Nagoya, 464-8601, Japan
- Graduate School of Science, Nagoya University, Chikusa, Nagoya, 464-8602, Japan
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6
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Ma Q, Grones P, Robert S. Auxin signaling: a big question to be addressed by small molecules. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:313-328. [PMID: 29237069 PMCID: PMC5853230 DOI: 10.1093/jxb/erx375] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 10/16/2017] [Indexed: 05/20/2023]
Abstract
Providing a mechanistic understanding of the crucial roles of the phytohormone auxin has been an important and coherent aspect of plant biology research. Since its discovery more than a century ago, prominent advances have been made in the understanding of auxin action, ranging from metabolism and transport to cellular and transcriptional responses. However, there is a long road ahead before a thorough understanding of its complex effects is achieved, because a lot of key information is still missing. The availability of an increasing number of technically advanced scientific tools has boosted the basic discoveries in auxin biology. A plethora of bioactive small molecules, consisting of the synthetic auxin-like herbicides and the more specific auxin-related compounds, developed as a result of the exploration of chemical space by chemical biology, have made the tool box for auxin research more comprehensive. This review mainly focuses on the compounds targeting the auxin co-receptor complex, demonstrates the various ways to use them, and shows clear examples of important basic knowledge obtained by their usage. Application of these precise chemical tools, together with an increasing amount of structural information for the major components in auxin action, will certainly aid in strengthening our insights into the complexity and diversity of auxin response.
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Affiliation(s)
- Qian Ma
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Sweden
| | - Peter Grones
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Sweden
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7
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Baumann M, Baxendale IR, Deplante F. A concise flow synthesis of indole-3-carboxylic ester and its derivatisation to an auxin mimic. Beilstein J Org Chem 2017; 13:2549-2560. [PMID: 29259664 PMCID: PMC5727791 DOI: 10.3762/bjoc.13.251] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 11/16/2017] [Indexed: 01/21/2023] Open
Abstract
An assembled suite of flow-based transformations have been used to rapidly scale-up the production of a novel auxin mimic-based herbicide which was required for preliminary field trials. The overall synthetic approach and optimisation studies are described along with a full description of the final reactor configurations employed for the synthesis as well as the downstream processing of the reaction streams.
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Affiliation(s)
- Marcus Baumann
- Department of Chemistry, University of Durham, South Road, Durham, Durham, DH1 3LE, UK
| | - Ian R Baxendale
- Department of Chemistry, University of Durham, South Road, Durham, Durham, DH1 3LE, UK
| | - Fabien Deplante
- Department of Chemistry, University of Durham, South Road, Durham, Durham, DH1 3LE, UK
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8
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Fukuda H, Nishikawa K, Fukunaga Y, Okuda K, Kodama K, Matsumoto K, Kano A, Shindo M. Synthesis of fluorescent molecular probes based on cis-cinnamic acid and molecular imaging of lettuce roots. Tetrahedron 2016. [DOI: 10.1016/j.tet.2016.08.060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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9
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Sokołowska K, Kizińska J, Szewczuk Z, Banasiak A. Auxin conjugated to fluorescent dyes--a tool for the analysis of auxin transport pathways. PLANT BIOLOGY (STUTTGART, GERMANY) 2014; 16:866-77. [PMID: 24397706 DOI: 10.1111/plb.12144] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 11/14/2013] [Indexed: 05/08/2023]
Abstract
Auxin is a small molecule involved in most processes related to plant growth and development. Its effect usually depends on the distribution in tissues and the formation of concentration gradients. Until now there has been no tool for the direct tracking of auxin transport at the cellular and tissue level; therefore the majority of studies have been based on various indirect methods. However, due to their various restrictions, relatively little is known about the relationship between various pathways of auxin transport and specific developmental processes. We present a new research tool: fluorescently labelled auxin in the form of a conjugate with two different fluorescent tracers, FITC and RITC, which allows direct observation of auxin transport in plant tissues. Chemical analysis and biological tests have shown that our conjugates have auxin-like biological activity and transport; therefore they can be used in all experimental systems as an alternative to IAA. In addition, the conjugates are a universal tool that can be applied in studies of all plant groups and species. The conjugation procedure presented in this paper can be adapted to other fluorescent dyes, which are constantly being improved. In our opinion, the conjugates greatly expand the possibilities of research concerning the role of auxin and its transport in different developmental processes in plants.
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Affiliation(s)
- K Sokołowska
- Department of Plant Developmental Biology, Institute of Experimental Biology, Faculty of Biological Sciences, University of Wrocław, Wrocław, Poland
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10
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Lee S, Sundaram S, Armitage L, Evans JP, Hawkes T, Kepinski S, Ferro N, Napier RM. Defining binding efficiency and specificity of auxins for SCF(TIR1/AFB)-Aux/IAA co-receptor complex formation. ACS Chem Biol 2014; 9:673-82. [PMID: 24313839 PMCID: PMC3964829 DOI: 10.1021/cb400618m] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
![]()
Structure–activity
profiles for the phytohormone auxin have
been collected for over 70 years, and a number of synthetic auxins
are used in agriculture. Auxin classification schemes and binding
models followed from understanding auxin structures. However, all
of the data came from whole plant bioassays, meaning the output was
the integral of many different processes. The discovery of Transport
Inhibitor-Response 1 (TIR1) and the Auxin F-Box (AFB) proteins as
sites of auxin perception and the role of auxin as molecular glue
in the assembly of co-receptor complexes has allowed the development
of a definitive quantitative structure–activity relationship
for TIR1 and AFB5. Factorial analysis of binding activities offered
two uncorrelated factors associated with binding efficiency and binding
selectivity. The six maximum-likelihood estimators of Efficiency are
changes in the overlap matrixes, inferring that Efficiency is related
to the volume of the electronic system. Using the subset of compounds
that bound strongly, chemometric analyses based on quantum chemical
calculations and similarity and self-similarity indices yielded three
classes of Specificity that relate to differential binding. Specificity
may not be defined by any one specific atom or position and is influenced
by coulomb matrixes, suggesting that it is driven by electrostatic
forces. These analyses give the first receptor-specific classification
of auxins and indicate that AFB5 is the preferred site for a number
of auxinic herbicides by allowing interactions with analogues having
van der Waals surfaces larger than that of indole-3-acetic acid. The
quality factors are also examined in terms of long-standing models
for the mechanism of auxin binding.
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Affiliation(s)
- Sarah Lee
- School
of Life Sciences, University of Warwick, Wellesbourne, Warwickshire CV35 9EF, U.K
| | - Shanthy Sundaram
- School
of Life Sciences, University of Warwick, Wellesbourne, Warwickshire CV35 9EF, U.K
- Centre
for Biotechnology, Nehru Science Complex, University of Allahabad, Allahabad-211002, Uttar Pradesh, India
| | - Lynne Armitage
- Centre
for Plant Sciences, University of Leeds, Leeds LS2 9JT, U.K
| | - John P. Evans
- Jealott’s
Hill Intl Research Centre, Syngenta, Ltd., Bracknell, Berkshire RG42 6EY, U.K
| | - Tim Hawkes
- Jealott’s
Hill Intl Research Centre, Syngenta, Ltd., Bracknell, Berkshire RG42 6EY, U.K
| | - Stefan Kepinski
- Centre
for Plant Sciences, University of Leeds, Leeds LS2 9JT, U.K
| | - Noel Ferro
- Mulliken
Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, Wegelerstr. 12, D-53115 Bonn, Germany
| | - Richard M. Napier
- School
of Life Sciences, University of Warwick, Wellesbourne, Warwickshire CV35 9EF, U.K
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11
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Song Y. Insight into the mode of action of 2,4-dichlorophenoxyacetic acid (2,4-D) as an herbicide. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2014; 56:106-13. [PMID: 24237670 DOI: 10.1111/jipb.12131] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 11/06/2013] [Indexed: 05/10/2023]
Abstract
2,4-Dichlorophenoxyacetic acid (2,4-D) was the first synthetic herbicide to be commercially developed and has commonly been used as a broadleaf herbicide for over 60 years. It is a selective herbicide that kills dicots without affecting monocots and mimics natural auxin at the molecular level. Physiological responses of dicots sensitive to auxinic herbicides include abnormal growth, senescence, and plant death. The identification of auxin receptors, auxin transport carriers, transcription factors response to auxin, and cross-talk among phytohormones have shed light on the molecular action mode of 2,4-D as a herbicide. Here, the molecular action mode of 2,4-D is highlighted according to the latest findings, emphasizing the physiological process, perception, and signal transduction under herbicide treatment.
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Affiliation(s)
- Yaling Song
- Key Laboratory of Tropical Plant Resource and Sustainable Use, Xishuangbanna Tropical Botanical Garden, the Chinese Academy of Sciences, Mengla, 666303, China
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12
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Nishikawa K, Fukuda H, Abe M, Nakanishi K, Taniguchi T, Nomura T, Yamaguchi C, Hiradate S, Fujii Y, Okuda K, Shindo M. Substituent effects of cis-cinnamic acid analogues as plant growh inhibitors. PHYTOCHEMISTRY 2013; 96:132-47. [PMID: 24070619 DOI: 10.1016/j.phytochem.2013.08.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 07/18/2013] [Accepted: 08/21/2013] [Indexed: 06/02/2023]
Abstract
1-O-cis-Cinnamoyl-β-D-glucopyranose is one of the most potent allelochemicals that has been isolated from Spiraea thunbergii Sieb by Hiradate et al. It derives its strong inhibitory activity from cis-cinnamic acid (cis-CA), which is crucial for phytotoxicity. By preparing and assaying a series of cis-CA analogues, it was previously found that the key features of cis-CA for lettuce root growth inhibition are a phenyl ring, cis-configuration of the alkene moiety, and carboxylic acid. On the basis of a structure-activity relationship study, the substituent effects on the aromatic ring of cis-CA were examined by systematic synthesis and the lettuce root growth inhibition assay of a series of cis-CA analogues having substituents on the aromatic ring. While ortho- and para-substituted analogues exhibited low potency in most cases, meta-substitution was not critical for potency, and analogues having a hydrophobic and sterically small substituent were more likely to be potent. Finally, several cis-CA analogues were found to be more potent root growth inhibitors than cis-CA.
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Affiliation(s)
- Keisuke Nishikawa
- Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga-koen, Kasuga 816-8580, Japan
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13
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Nishikawa K, Fukuda H, Abe M, Nakanishi K, Tazawa Y, Yamaguchi C, Hiradate S, Fujii Y, Okuda K, Shindo M. Design and synthesis of conformationally constrained analogues of cis-cinnamic acid and evaluation of their plant growth inhibitory activity. PHYTOCHEMISTRY 2013; 96:223-34. [PMID: 24176527 DOI: 10.1016/j.phytochem.2013.10.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 09/19/2013] [Accepted: 10/01/2013] [Indexed: 06/02/2023]
Abstract
1-O-cis-Cinnamoyl-β-D-glucopyranose is known to be one of the most potent allelochemical candidates and was isolated from Spiraea thunbergii Sieb by Hiradate et al. (2004), who suggested that it derived its strong inhibitory activity from cis-cinnamic acid, which is crucial for phytotoxicity. In this study, key structural features and substituent effects of cis-cinnamic acid (cis-CA) on lettuce root growth inhibition was investigated. These structure-activity relationship studies indicated the importance of the spatial relationship of the aromatic ring and carboxylic acid moieties. In this context, conformationally constrained cis-CA analogues, in which the aromatic ring and cis-olefin were connected by a carbon bridge, were designed, synthesized, and evaluated as plant growth inhibitors. The results of the present study demonstrated that the inhibitory activities of the five-membered and six-membered bridged compounds were enhanced, up to 0.27 μM, and were ten times higher than cis-CA, while the potency of the other compounds was reduced.
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Affiliation(s)
- Keisuke Nishikawa
- Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga-koen, Kasuga 816-8580, Japan
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14
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Böttcher C, Boss PK, Davies C. Acyl substrate preferences of an IAA-amido synthetase account for variations in grape (Vitis vinifera L.) berry ripening caused by different auxinic compounds indicating the importance of auxin conjugation in plant development. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:4267-80. [PMID: 21543520 PMCID: PMC3153680 DOI: 10.1093/jxb/err134] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Nine Gretchen Hagen (GH3) genes were identified in grapevine (Vitis vinifera L.) and six of these were predicted on the basis of protein sequence similarity to act as indole-3-acetic acid (IAA)-amido synthetases. The activity of these enzymes is thought to be important in controlling free IAA levels and one auxin-inducible grapevine GH3 protein, GH3-1, has previously been implicated in the berry ripening process. Ex planta assays showed that the expression of only one other GH3 gene, GH3-2, increased following the treatment of grape berries with auxinic compounds. One of these was the naturally occurring IAA and the other two were synthetic, α-naphthalene acetic acid (NAA) and benzothiazole-2-oxyacetic acid (BTOA). The determination of steady-state kinetic parameters for the recombinant GH3-1 and GH3-2 proteins revealed that both enzymes efficiently conjugated aspartic acid (Asp) to IAA and less well to NAA, while BTOA was a poor substrate. GH3-2 gene expression was induced by IAA treatment of pre-ripening berries with an associated increase in levels of IAA-Asp and a decrease in free IAA levels. This indicates that GH3-2 responded to excess auxin to maintain low levels of free IAA. Grape berry ripening was not affected by IAA application prior to veraison (ripening onset) but was considerably delayed by NAA and even more so by BTOA. The differential effects of the three auxinic compounds on berry ripening can therefore be explained by the induction and acyl substrate specificity of GH3-2. These results further indicate an important role for GH3 proteins in controlling auxin-related plant developmental processes.
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15
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Simon S, Petrášek J. Why plants need more than one type of auxin. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2011; 180:454-60. [PMID: 21421392 DOI: 10.1016/j.plantsci.2010.12.007] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2010] [Revised: 12/13/2010] [Accepted: 12/15/2010] [Indexed: 05/04/2023]
Abstract
The versatile functionality and physiological importance of the phytohormone auxin is a major focus of attention in contemporary plant science. Recent studies have substantially contributed to our understanding of the molecular mechanisms underlying the physiological role of auxin in plant development. The mechanism of auxin action includes both fast responses not involving gene expression, possibly mediated by Auxin Binding Protein 1 (ABP1), and slower responses requiring auxin-regulated gene expression mediated by F-box proteins. These two mechanisms of action have been described to varying degrees for the major endogenous auxin indole-3-acetic acid (IAA) and for the synthetic auxins 2,4-dichlorophenoxyacetic acid (2,4-D) and naphthalene-1-acetic acid (NAA). However, in addition to IAA, plants synthesize three other compounds that are commonly regarded as "endogenous auxins", namely, 4-chloroindole-3-acetic acid (4-Cl-IAA), indole-3-butyric acid (IBA) and phenylacetic acid (PAA). Although a spectrum of auxinic effects has been identified for all these as well as several other endogenous compounds, we remain largely ignorant of many aspects of their mechanisms of action and the extent to which they contribute to auxin-regulated plant development. Here, we briefly summarize the action of IBA, 4-Cl-IAA and PAA, and discuss the extent to which their action overlaps with that of IAA or results from their metabolic conversions to IAA. Other possible pathways for their action are considered. We present a scheme for homeostatic regulation of IAA levels that embraces other endogenous auxins in terms of the described mechanism of auxin action including its receptor and downstream signal transduction events.
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Affiliation(s)
- Sibu Simon
- Institute of Experimental Botany, ASCR, Rozvojová 263, 16502 Praha 6, Czech Republic
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16
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Bailly A, Yang H, Martinoia E, Geisler M, Murphy AS. Plant Lessons: Exploring ABCB Functionality Through Structural Modeling. FRONTIERS IN PLANT SCIENCE 2011; 2:108. [PMID: 22639627 PMCID: PMC3355715 DOI: 10.3389/fpls.2011.00108] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 12/17/2011] [Indexed: 05/18/2023]
Abstract
In contrast to mammalian ABCB1 proteins, narrow substrate specificity has been extensively documented for plant orthologs shown to catalyze the transport of the plant hormone, auxin. Using the crystal structures of the multidrug exporters Sav1866 and MmABCB1 as templates, we have developed structural models of plant ABCB proteins with a common architecture. Comparisons of these structures identified kingdom-specific candidate substrate-binding regions within the translocation chamber formed by the transmembrane domains of ABCBs from the model plant Arabidopsis. These results suggest an early evolutionary divergence of plant and mammalian ABCBs. Validation of these models becomes a priority for efforts to elucidate ABCB function and manipulate this class of transporters to enhance plant productivity and quality.
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Affiliation(s)
- Aurélien Bailly
- Plant Biology, Department of Biology, University of FribourgFribourg, Switzerland
- Institute of Plant Biology, Zurich–Basel Plant Science Center, University of ZurichZurich, Switzerland
| | - Haibing Yang
- Department of Horticulture and Landscape Architecture, Purdue UniversityWest Lafayette, IN, USA
| | - Enrico Martinoia
- Institute of Plant Biology, Zurich–Basel Plant Science Center, University of ZurichZurich, Switzerland
| | - Markus Geisler
- Plant Biology, Department of Biology, University of FribourgFribourg, Switzerland
- Institute of Plant Biology, Zurich–Basel Plant Science Center, University of ZurichZurich, Switzerland
- *Correspondence: Markus Geisler, Plant Biology, Department of Biology, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland. e-mail:
| | - Angus S. Murphy
- Department of Horticulture and Landscape Architecture, Purdue UniversityWest Lafayette, IN, USA
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