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Brazier-Hicks M, Howell A, Cohn J, Hawkes T, Hall G, Mcindoe E, Edwards R. Chemically induced herbicide tolerance in rice by the safener metcamifen is associated with a phased stress response. J Exp Bot 2020; 71:411-421. [PMID: 31565749 PMCID: PMC6913702 DOI: 10.1093/jxb/erz438] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 09/22/2019] [Indexed: 05/22/2023]
Abstract
The closely related sulphonamide safeners, metcamifen and cyprosulfamide, were tested for their ability to protect rice from clodinafop-propargyl, a herbicide normally used in wheat. While demonstrating that both compounds were equally bioavailable in planta, only metcamifen prevented clodinafop from damaging seedlings, and this was associated with the enhanced detoxification of the herbicide. Transcriptome studies in rice cultures demonstrated that whereas cyprosulfamide had a negligible effect on gene expression over a 4 h exposure, metcamifen perturbed the abundance of 590 transcripts. Changes in gene expression with metcamifen could be divided into three phases, corresponding to inductions occurring over 30 min, 1.5 h and 4 h. The first phase of gene induction was dominated by transcription factors and proteins of unknown function, the second by genes involved in herbicide detoxification, while the third was linked to cellular homeostasis. Analysis of the inducible genes suggested that safening elicited similar gene families to those associated with specific biotic and abiotic stresses, notably those elicited by abscisic acid, salicylic acid, and methyl jasmonate. Subsequent experiments with safener biomarker genes induced in phase 1 and 2 in rice cell cultures provided further evidence of similarities in signalling processes elicited by metcamifen and salicylic acid.
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Affiliation(s)
- Melissa Brazier-Hicks
- Agriculture, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
| | | | - Jonathan Cohn
- Syngenta Crop Protection, LLC, 9 Davis Drive, Research Triangle Park, NC, USA
| | - Tim Hawkes
- Syngenta, Jealott’s Hill, Bracknell, Berkshire, UK
| | - Gavin Hall
- Syngenta, Jealott’s Hill, Bracknell, Berkshire, UK
| | | | - Robert Edwards
- Agriculture, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
- Correspondence:
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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] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
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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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Ma R, Kaundun SS, Tranel PJ, Riggins CW, McGinness DL, Hager AG, Hawkes T, McIndoe E, Riechers DE. Distinct detoxification mechanisms confer resistance to mesotrione and atrazine in a population of waterhemp. Plant Physiol 2013; 163:363-77. [PMID: 23872617 PMCID: PMC3762656 DOI: 10.1104/pp.113.223156] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 07/17/2013] [Indexed: 05/19/2023]
Abstract
Previous research reported the first case of resistance to mesotrione and other 4-hydroxyphenylpyruvate dioxygenase (HPPD) herbicides in a waterhemp (Amaranthus tuberculatus) population designated MCR (for McLean County mesotrione- and atrazine-resistant). Herein, experiments were conducted to determine if target site or nontarget site mechanisms confer mesotrione resistance in MCR. Additionally, the basis for atrazine resistance was investigated in MCR and an atrazine-resistant but mesotrione-sensitive population (ACR for Adams County mesotrione-sensitive but atrazine-resistant). A standard sensitive population (WCS for Wayne County herbicide-sensitive) was also used for comparison. Mesotrione resistance was not due to an alteration in HPPD sequence, HPPD expression, or reduced herbicide absorption. Metabolism studies using whole plants and excised leaves revealed that the time for 50% of absorbed mesotrione to degrade in MCR was significantly shorter than in ACR and WCS, which correlated with previous phenotypic responses to mesotrione and the quantity of the metabolite 4-hydroxy-mesotrione in excised leaves. The cytochrome P450 monooxygenase inhibitors malathion and tetcyclacis significantly reduced mesotrione metabolism in MCR and corn (Zea mays) excised leaves but not in ACR. Furthermore, malathion increased mesotrione activity in MCR seedlings in greenhouse studies. These results indicate that enhanced oxidative metabolism contributes significantly to mesotrione resistance in MCR. Sequence analysis of atrazine-resistant (MCR and ACR) and atrazine-sensitive (WCS) waterhemp populations detected no differences in the psbA gene. The times for 50% of absorbed atrazine to degrade in corn, MCR, and ACR leaves were shorter than in WCS, and a polar metabolite of atrazine was detected in corn, MCR, and ACR that cochromatographed with a synthetic atrazine-glutathione conjugate. Thus, elevated rates of metabolism via distinct detoxification mechanisms contribute to mesotrione and atrazine resistance within the MCR population.
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Hawkes T, Pline-Srnic W, Dale R, Friend E, Hollinshead T, Howe P, Thompson P, Viner R, Greenland A. D-glufosinate as a male sterility agent for hybrid seed production. Plant Biotechnol J 2011; 9:301-14. [PMID: 20678098 DOI: 10.1111/j.1467-7652.2010.00549.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A chemical male sterility system based on anther-localized conversion of the inactive D-enantiomer of the herbicide, glufosinate (2-amino-4-(methylphosphinyl)-butanoate) to the phytotoxic L is described. Highly pure D-glufosinate was isolated in >98% enantiomeric excess from the racemate via fermentation with a strain of Escherichia coli expressing the PAT (L-glufosinate N-acetyl transferase) gene and purification of the unreacted D-enantiomer from the broth by ion exchange. A modified (F58K, M213S) form of the D-amino acid oxidase (DAAO) (EC 1.4.3.3) from Rhodosporidium toruloides was designed, tested in vitro and found to efficiently oxidize D-glufosinate to its 2-oxo derivative [2-oxo-4-(methylphosphinyl)-butanoic acid]. Tobacco (Nicotiana tabacum) plants were transformed to express this modified oxidase under control of the TAP1 tapetum-specific promoter. A number of the resultant transgenic lines exhibited complete male sterility that persisted for two or more weeks immediately following foliar treatment with 75 or 200 g/ha of D-glufosinate without exhibiting obvious phytotoxic symptoms or any measurable decline in female fertility. Similarly, plants containing the same construct and, additionally, a PAT gene expressed from a plastocyanin promoter exhibited significantly reduced male fertility and no reduction in female fertility following foliar application of racemic glufosinate. Thus, foliar application of d-glufosinate either purified or as the commercial herbicide, combined with anther expression of a modified DAAO promises to provide a cost-effective conditional chemical male sterility system with the characteristics necessary for practical F₁ hybrid seed production.
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Affiliation(s)
- Tim Hawkes
- Syngenta, Jealott's Hill Research Centre, Bracknell, Berks, UK.
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Yang X, Guschina IA, Hurst S, Wood S, Langford M, Hawkes T, Harwood JL. The action of herbicides on fatty acid biosynthesis and elongation in barley and cucumber. Pest Manag Sci 2010; 66:794-800. [PMID: 20533380 DOI: 10.1002/ps.1944] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
BACKGROUND Herbicides that affect lipid metabolism have been used commercially for many years. Here, napropamide, diphenamid, dimethachlor and cafenstrole are compared; these have all been classified by the Herbicide Resistance Action Committee (HRAC) as K(3) herbicides and inhibitors of cell division and/or synthesis of very-long-chain fatty acids (VLCFAs). In addition, spiro-decanedione A and pinoxaden dione are compared as inhibitors of lipid synthesis through inhibition of acetyl-CoA carboxylase (ACCase). RESULTS Whereas the chloracetamide dimethachlor and the carboxyamide cafenstrole potently inhibited VLCFA synthesis in both barley and cucumber, the acetamides napropamide and diphenamid which are also classified as K(3) herbicides and likewise the unclassified herbicide cinmethylin did not. The graminicide pinoxaden dione inhibited de novo fatty acid synthesis in barley, but not in cucumber, and correspondingly inhibited the plastid form of maize ACCase much more than the cytosolic form (IC(50) values of 0.1 and 17 microM). By contrast, spiro-decanedione A exhibited herbicidal effects not only on grasses but also on broad leaves, strongly inhibited maize cytosolic ACCase and inhibited synthesis of VLCFAs in cucumber. CONCLUSIONS The acetamides napropamide and diphenamid, which do not inhibit VLCFA synthesis, should be classified separately from K(3) herbicides that do. Pinoxaden dione and spiro-decanedione A represent new classes of chemicals acting on plant lipid synthesis.
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Affiliation(s)
- Xueying Yang
- School of Biosciences, Cardiff University, Cardiff, Wales, UK
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Sadre R, Frentzen M, Saeed M, Hawkes T. Catalytic reactions of the homogentisate prenyl transferase involved in plastoquinone-9 biosynthesis. J Biol Chem 2010; 285:18191-8. [PMID: 20400515 PMCID: PMC2881743 DOI: 10.1074/jbc.m110.117929] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Revised: 04/15/2010] [Indexed: 11/06/2022] Open
Abstract
Homogentisate solanesyl transferase (HST) catalyzes the prenylation and decarboxylation of homogentisate to form 2-methyl-6-solanesyl-1,4-benzoquinol, the first intermediate in plastoquinone-9 biosynthesis. In vitro, HST from Spinacia oleracea L., Arabidopsis thaliana, and Chlamydomonas reinhardtii were all found to use not only solanesyl diphosphate but also short chain prenyl diphosphates of 10-20 carbon atoms as prenyl donors. Surprisingly, with these donors, prenyl transfer was largely decoupled from decarboxylation, and thus the major products were 6-prenyl-1,4-benzoquinol-2-methylcarboxylates rather than the expected 2-methyl-6-prenyl-1,4-benzoquinols. The 6-prenyl-1,4-benzoquinol-2-methylcarboxylates were not substrates for HST-catalyzed decarboxylation, and the enzyme kinetics associated with forming these products appeared quite distinct from those for 2-methyl-6-prenyl-1,4-benzoquinol formation in respect of catalytic rate, substrate K(m) value, and the pattern of inhibition by haloxydine, a molecule that appeared to act as a dead end mimic of homogentisate. These observations were reconciled into a simple model for the HST mechanism. Here, prenyl diphosphate binds to HST to form at least two alternative complexes that go on to react differently with homogentisate and prenylate it either with or without it first being decarboxylated. It is supposed that solanesyl diphosphate binds tightly and preferentially in the mode that compels prenylation with decarboxylation.
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Affiliation(s)
- Radin Sadre
- Institute for Biology I, Botany, RWTH Aachen University, Worringerweg 1, 52056 Aachen, Germany.
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Parker GF, Higgins TP, Hawkes T, Robson RL. Rhizobium (Sinorhizobium) meliloti phn genes: characterization and identification of their protein products. J Bacteriol 1999; 181:389-95. [PMID: 9882650 PMCID: PMC93390 DOI: 10.1128/jb.181.2.389-395.1999] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Escherichia coli, the phn operon encodes proteins responsible for the uptake and breakdown of phosphonates. The C-P (carbon-phosphorus) lyase enzyme encoded by this operon which catalyzes the cleavage of C-P bonds in phosphonates has been recalcitrant to biochemical characterization. To advance the understanding of this enzyme, we have cloned DNA from Rhizobium (Sinorhizobium) meliloti that contains homologues of the E. coli phnG, -H, -I, -J, and -K genes. We demonstrated by insertional mutagenesis that the operon from which this DNA is derived encodes the R. meliloti C-P lyase. Furthermore, the phenotype of this phn mutant shows that the C-P lyase has a broad substrate specificity and that the organism has another enzyme that degrades aminoethylphosphonate. A comparison of the R. meliloti and E. coli phn genes and their predicted products gave new information about C-P lyase. The putative R. meliloti PhnG, PhnH, and PhnK proteins were overexpressed and used to make polyclonal antibodies. Proteins of the correct molecular weight that react with these antibodies are expressed by R. meliloti grown with phosphonates as sole phosphorus sources. This is the first in vivo demonstration of the existence of these hitherto hypothetical Phn proteins.
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Affiliation(s)
- G F Parker
- School of Animal and Microbial Sciences, University of Reading, Reading RG6 6AJ, United Kingdom
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Wilkinson KW, Baker PJ, Rice DW, Rodgers HF, Stillman TJ, Hawkes T, Thomas P, Edwards L. Crystallization and analysis of the subunit assembly and quaternary structure of imidazoleglycerol phosphate dehydratase fromSaccharomyces cerevisiae. Acta Crystallogr D Biol Crystallogr 1995; 51:845-7. [PMID: 15299823 DOI: 10.1107/s0907444995001569] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Imidazoleglycerol phosphate dehydratase (IGPD) from Saccharomyces cerevisiae has been crystallized in the presence of a range of divalent cations using the hanging-drop method of vapour diffusion with ammonium sulfate or polyethylene glycol (PEG) 4000 as the precipitants. X-ray precession photographs have established that the crystals formed with ammonium sulfate (form A) belong to the space group F432, with cell parameter a = 177.5 A and a single subunit in the asymmetric unit. A preliminary data set collected to 6 A resolution on a two-detector San Diego Multiwire area detector has established that the crystals formed with PEG 4000 (form B) belong to either of the special pair of space groups I23 or I2(1)3, with cell parameter a = 131.0 A. A self-rotation function has been calculated using these data and indicates that the cell axes show pseudo fourfold symmetry consistent with a dimer in the asymmetric unit in this crystal form. Light-scattering studies indicate that in the presence of Mn(2+) and a number of other divalent cations IGPD undergoes assembly to a particle of molecular weight approximately 500 kDa. Given the subunit molecular weight of 23 kDa together with the symmetry of the crystals it would indicate that the most likely quaternary structure for this enzyme is based on a 24-mer in 432 symmetry.
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Affiliation(s)
- K W Wilkinson
- Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, England
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Abstract
A new pathway is proposed for the biosynthesis of the plant sulpholipid, sulphoquinovosyldiacylglycerol. The pathway begins at UDP-glucose and involves the formation therefrom of UDP-4-ketoglucose-5-ene to which is subsequently added sulphite (or its metabolic equivalent). Evidence consistent with this pathway, rather than with the previously proposed 'sulphoglycolytic' route, was obtained from experiments with pea chloroplast preparations. The evidence included the failure of potential inhibitors of the sulphoglycolytic pathway to alter the rate of synthesis of sulpholipid and the stimulation of the incorporation of 35SO4(2-) into the latter by UTP. Radioactivity was effectively incorporated into sulpholipid from UDP-[14C]glucose and this radiolabelling was stimulated by the addition of methyl alpha-glucose-enide or of an enzyme system known to be forming (although not accumulating) UDP-4-ketoglucose-5-ene. This new pathway is also consistent with other data in the literature.
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Affiliation(s)
- C E Pugh
- School of Molecular and Medical Biosciences, University of Wales Cardiff, U.K
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Hawkes T, Merrick M, Dixon R. Interaction of purified NtrC protein with nitrogen regulated promoters from Klebsiella pneumoniae. Mol Gen Genet 1985; 201:492-8. [PMID: 3911027 DOI: 10.1007/bf00331345] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The product of the Klebsiella pneumoniae nitrogen regulatory gene ntrC has been purified and shown to be a dimeric protein of subunit molecular weight 54Kd, designated NtrC. In an in vitro coupled transcription-translation system NtrC inhibited expression from both the ntrBC and glnA promoters. NtrC bound to both of these ntr repressible promoters with equal affinity, but did not bind to the activatable nitrogen fixation promoters nifF or nifLA. NtrC makes contact with nucleotides flanking the -10 region of the glnA (RNA2) promoter at sequences homologous with the proposed consensus binding site.
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