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Noguera MM, Rangani G, Heiser J, Bararpour T, Steckel LE, Betz M, Porri A, Lerchl J, Zimmermann S, Nichols RL, Roma-Burgos N. Functional PPO2 mutations: co-occurrence in one plant or the same ppo2 allele of herbicide-resistant Amaranthus palmeri in the US mid-south. PEST MANAGEMENT SCIENCE 2021; 77:1001-1012. [PMID: 32990410 DOI: 10.1002/ps.6111] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 09/22/2020] [Accepted: 09/29/2020] [Indexed: 05/27/2023]
Abstract
BACKGROUND Protoporphyrinogen IX oxidase 2 (PPO2) inhibitors are important for the management of glyphosate- and acetolactate synthase-resistant Palmer amaranth [Amaranthus palmeri (S.) Wats.]. The evolving resistance to PPO inhibitors is of great concern. We surveyed the evolution of resistance to fomesafen in the US Mid-south and determined its correlation with the known functional PPO2 target-site mutations (TSM). RESULTS The 167 accessions analyzed were grouped into five categories, four resistant (147) and one susceptible (20). Arkansas accessions constituted 100% of the susceptible group while the Missouri accessions comprised 60% of the most resistant category. The majority of Mississippi accessions (88%) clustered in the high-survival-high-injury category, manifesting an early-stage resistance evolution. One hundred and fifteen accessions were genotyped for four known TSMs; 74% of accessions carried at least one TSM. The most common single TSM was ΔG210 (18% of accessions) and the predominant double mutation was ΔG210 + G399A (17%). Other mutations are likely less favorable, hence are rare. All TSMs were detected in three accessions. Further examination revealed that 9 and two individuals carried G399A + G210 and G399A + R128G TSM in the same allele, respectively. The existence of these combinations is supported by molecular modeling. CONCLUSIONS Resistance to PPO inhibitors is widespread across the Mid-southern USA. Highly resistant field populations have plants with multiple mutations. G399A is the most prone to co-occur with other ppo2 mutations in the same allele. Mutation at R128 in the configuration of the PPO2 catalytic domain restrains the co-occurrence of R128G with ΔG210, making ΔG210 + G399A the most plausible, tolerable functional mutation combination to co-occur in the same ppo2 allele.
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Affiliation(s)
- Matheus M Noguera
- Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AK, USA
| | - Gulab Rangani
- Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AK, USA
| | - James Heiser
- Food & Natural Resources, Fisher Delta Research Center, University of Missouri College of Agriculture, Portageville, MO, USA
| | - Taghi Bararpour
- Delta Research and Extension Center, Mississippi State University, Stoneville, MS, USA
| | | | | | | | | | | | | | - Nilda Roma-Burgos
- Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AK, USA
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Huynh K, Reinhold D. Uptake, translocation, and metabolism of sulfamethazine by Arabidopsis thaliana: distinguishing between phytometabolites and abiotic transformation products in the media. INTERNATIONAL JOURNAL OF PHYTOREMEDIATION 2019; 22:412-419. [PMID: 31549518 DOI: 10.1080/15226514.2019.1667952] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Plant accumulation of antibiotic residues presents potential risks to human and ecosystem health. However, the phytometabolic pathways of antibiotics following plant uptake are still largely uncharacterized. This study investigated the phytometabolism of sulfamethazine (SMT) by Arabidopsis thaliana, using 14C-labeled and unlabeled SMT. SMT was accumulated in both roots and shoots of axenic A. thaliana plants (123.7 ± 12.3 and 22.7 ± 1.0 µg/kg fw, respectively) after 21 days of exposure. However, the parent 14C-SMT accounted for only 1.7 ± 0.01% of the total 14C-radioactivity in plant tissues. The majority of 14C-radioactivity taken up by plants was present as bound residues (42.0-68.2% of initially applied 14C-SMT), while extractable 14C-residues accounted for only 7.7-12.6%. A. thaliana metabolized SMT primarily through glycosylation at the N4-nitrogen atom. Additionally, other products, including pterin-SMT, methylsalicylate-SMT, N4-formyl-SMT, desulfo-SMT, hydroxyl-SMT, N4-acetyl-SMT, desamino-SMT, and 2-amino-4,6-dimethylpyrimidine, were also identified. Notably, a portion of the extractable metabolites was excreted into the culture media, requiring characterization of these metabolites as either excreted phytometabolites or abiotic transformation products of SMT based on comparisons between experimental and control reactors.
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Affiliation(s)
- Khang Huynh
- Department of Biosystems and Agricultural Engineering, Michigan State University, East Lansing, MI, USA
- Plant and Environmental Sciences Department, Clemson University, Clemson, SC, USA
| | - Dawn Reinhold
- Department of Biosystems and Agricultural Engineering, Michigan State University, East Lansing, MI, USA
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Lian JL, Ren LS, Zhang C, Yu CY, Huang Z, Xu AX, Dong JG. How exposure to ALS-inhibiting gametocide tribenuron-methyl induces male sterility in rapeseed. BMC PLANT BIOLOGY 2019; 19:124. [PMID: 30940071 PMCID: PMC6444545 DOI: 10.1186/s12870-019-1722-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Accepted: 03/17/2019] [Indexed: 06/08/2023]
Abstract
BACKGROUND Acetolactate synthase (ALS)-inhibiting herbicide tribenuron-methyl (TBM) is an efficient gametocide that can cause rapeseed (Brassica napus L.) to become male sterile and outcrossing. To find the reason the TBM treatment leads to male sterility, an integrated study using cytological, physiological, and transcriptomic methods was conducted. RESULTS Some temporary symptoms, including the discoloration of young leaves and a short halt of raceme elongation, were observed in the rapeseed plants exposed to TBM at an application rate of 1 μg per plant. Both chloroplasts in young leaves and plastids in anthers were deformed. TBM also reduced the leaf photosynthetic rate and the contents of chlorophyll, soluble sugar and pyruvate. Both the tapetal cells and uni-nucleate microspores in the treated plants showed large autophagic vacuoles, and the tissue degenerated quickly. A transcriptomic comparison with the control identified 200 upregulated and 163 downregulated differential expression genes in the small flower buds of the TBM treatment. The genes encoding functionally important proteins, including glucan endo-1,3-beta-glucosidase A6, QUARTET3 (QRT3), ARABIDOPSIS ANTHER 7 (ATA7), non-specific lipid-transfer protein LTP11 and LTP12, histone-lysine N-methyltransferase ATXR6, spermidine coumaroyl-CoA acyltransferase (SCT), and photosystem II reaction centre protein psbB, were downregulated by TBM exposure. Some important genes encoding autophagy-related protein ATG8a and metabolic detoxification related proteins, including DTX1, DTX6, DTX35, cytosolic sulfotransferase SOT12, and six members of glutathione S-transferase, were upregulated. In addition, several genes related to hormone stimulus, such as 1-aminocyclopropane-1-carboxylate synthase 8 (ACS8), ethylene-responsive factor ERF1A, ERF1, ERF71, CRF6, and RAP2-3, were also upregulated. The transcriptional regulation is in accordance with the functional abnormalities of pollen wall formation, lipid metabolism, chloroplast structure, ethylene generation, cell cycle, and tissue autophagy. CONCLUSION The results suggested that except for ALS, the metabolic pathways related to lipid metabolism, pollen exine formation, photosynthesis and hormone response are associated with male sterility induced by TBM. The results provide new insight into the molecular mechanisms of inducing male sterility by sulfonylurea.
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Affiliation(s)
- Jing-long Lian
- College of Agronomy, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Li-Suo Ren
- College of Agronomy, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Cong Zhang
- College of Agronomy, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Cheng-Yu Yu
- College of Agronomy, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Zhen Huang
- College of Agronomy, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Ai-Xia Xu
- College of Agronomy, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Jun-Gang Dong
- College of Agronomy, Northwest A&F University, Yangling, 712100 Shaanxi China
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Li D, Gao Q, Xu L, Pang S, Liu Z, Wang C, Tan W. Characterization of glutathione S-transferases in the detoxification of metolachlor in two maize cultivars of differing herbicide tolerance. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2017; 143:265-271. [PMID: 29183603 DOI: 10.1016/j.pestbp.2016.12.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 11/28/2016] [Accepted: 12/05/2016] [Indexed: 05/27/2023]
Abstract
Glutathione S-transferases (GSTs) have been widely studied in relation to their role in herbicide tolerance and detoxification. However, a detailed characterization of GSTs from herbicide tolerant and sensitive maize cultivars is still lacking. In this study, we determined the mechanism of differential tolerance between two maize cultivars which had 4-fold difference tolerance to metolachlor. The metabolism rate of metolachlor was more rapid in the tolerant cultivar (Zea mays L. cv Nongda86) than the susceptible one (Zea mays L. cv Zhengda958). Addition of the GST inhibitor ethacrynic acid reduced the metabolism of metolachlor indicating the involvement of GSTs in the differential detoxification of metolachlor. The expression profiles of 32 GST isozymes were measured using quantitative RT-PCR. The results showed the expression of GST genes were slightly up-regulated in Nongda86, but severely inhibited in Zhengdan958 24h after metolachlor treatment. The genes GSTI, GSTIII, GSTIV, GST5, GST6 and GST7, which can detoxify chloroacetanilide herbicides, were all expressed higher in Nongda86 compared to Zhendgan958. The result of GST activity was consistent with the gene expression profiles. Collectively, higher-level expression of GST genes, leading to higher GST activity and faster herbicide detoxification, appears to be responsible for the difference in tolerance to metolachlor in two maize cultivars.
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Affiliation(s)
- Dongzhi Li
- Engineering Research Centre of Plant Growth Regulators, Ministry of Education, College of Science, China Agricultural University, Beijing, PR China
| | | | - Li Xu
- Engineering Research Centre of Plant Growth Regulators, Ministry of Education, College of Science, China Agricultural University, Beijing, PR China
| | - Sen Pang
- Engineering Research Centre of Plant Growth Regulators, Ministry of Education, College of Science, China Agricultural University, Beijing, PR China
| | - Zhiqian Liu
- Department of Economic Development, Jobs, Transport and Resources, AgriBio, 5 Ring Road, Bundoora, Victoria 3083, Australia
| | - Chengju Wang
- Engineering Research Centre of Plant Growth Regulators, Ministry of Education, College of Science, China Agricultural University, Beijing, PR China.
| | - Weiming Tan
- Engineering Research Centre of Plant Growth Regulators, Ministry of Education, College of Agronomy and Biotechnology, China Agricultural University, Beijing, PR China.
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Mathews S, Reinhold D. Biosolid-borne tetracyclines and sulfonamides in plants. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2013; 20:4327-4338. [PMID: 23591931 DOI: 10.1007/s11356-013-1693-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 03/28/2013] [Indexed: 06/02/2023]
Abstract
Tetracyclines and sulfonamides used in human and animal medicine are released to terrestrial ecosystems from wastewater treatment plants or by direct manure application. The interactions between plants and these antibiotics are numerous and complex, including uptake and accumulation, phytometabolism, toxicity responses, and degradation in the rhizosphere. Uptake and accumulation of antibiotics have been studied in plants such as wheat, maize, potato, vegetables, and ornamentals. Once accumulated in plant tissue, organic contaminants can be metabolized through a sequential process of transformation, conjugation through glycosylation and glutathione pathways, and ultimately sequestration into plant tissue. While studies have yet to fully elucidate the phytometabolism of tetracyclines and sulfonamides, an in-depth review of plant and mammalian studies suggest multiple potential transformation and conjugation pathways for tetracyclines and sulfonamides. The presence of contaminants in the vicinity or within the plants can elicit stress responses and defense mechanisms that can help tolerate the negative effects of contaminants. Antibiotics can change microbial communities and enzyme activity in the rhizosphere, potentially inducing microbial antibiotic resistance. On the other hand, the interaction of microbes and root exudates on pharmaceuticals in the rhizosphere can result in degradation of the parent molecule to less toxic compounds. To fully characterize the environmental impacts of increased antibiotic use in human medicine and animal production, further research is essential to understand the effects of different antibiotics on plant physiology and productivity, uptake, translocation, and phytometabolism of antibiotics, and the role of antibiotics in the rhizosphere.
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Affiliation(s)
- Shiny Mathews
- Department of Biosystems and Agricultural Engineering, Michigan State University, East Lansing, MI 48824, USA.
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Feng ZZ, Li QF, Zhang J, Zhang J, Huang X, Lu P, Li SP. Microbial degradation of fomesafen by a newly isolated strain Pseudomonas zeshuii BY-1 and the biochemical degradation pathway. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:7104-7110. [PMID: 22757645 DOI: 10.1021/jf3011307] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Fomesafen is a diphenyl ether herbicide used to control the growth of broadleaf weeds in bean fields. Although the degradation of fomesafen in soils was thought to occur primarily by microbial activity, little was known about the kinetic and metabolic behaviors of this herbicide. This paper reported the capability of the newly isolated strain Pseudomonas zeshuii BY-1 to use fomesafen as the sole source of carbon in pure culture for its growth. Up to 88.7% of 50 mg of L(-1) fomesafen was degraded by this bacterium in mineral medium within 3 days. Strain BY-1 could also degrade other diphenyl ethers, including lactofen, acifluorfen, and fluoroglycofen. During the fomesafen degradation, five metabolites were detected and identified by liquid chromatography-mass spectrometry and tandem mass spectrometry. The primary degradation pathway of fomesafen might be the reduction of the nitro group to an amino group, followed by the acetylation of the amino derivative, dechlorination, and cleavage of the S-N bond. The addition of the BY-1 stain into soils treated with fomesafen resulted in a higher degradation rate than that observed in uninoculated soils, and the bacteria community in contaminated soil recovered after inoculation of the BY-1 stain. On the basis of these results, strain P. zeshuii BY-1 has the potential to be used in the bioremediation of fomesafen-contaminated soils.
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Affiliation(s)
- Zhao-zhong Feng
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, People's Republic of China
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Cummins I, Dixon DP, Freitag-Pohl S, Skipsey M, Edwards R. Multiple roles for plant glutathione transferases in xenobiotic detoxification. Drug Metab Rev 2011; 43:266-80. [PMID: 21425939 DOI: 10.3109/03602532.2011.552910] [Citation(s) in RCA: 229] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Discovered 40 years ago, plant glutathione transferases (GSTs) now have a well-established role in determining herbicide metabolism and selectivity in crops and weeds. Within the GST superfamily, the numerous and plant-specific phi (F) and tau (U) classes are largely responsible for catalyzing glutathione-dependent reactions with xenobiotics, notably conjugation leading to detoxification and, more rarely, bioactivating isomerizations. In total, the crystal structures of 10 plant GSTs have been solved and a highly conserved N-terminal glutathione binding domain and structurally diverse C-terminal hydrophobic domain identified, along with key coordinating residues. Unlike drug-detoxifying mammalian GSTs, plant enzymes utlilize a catalytic serine in place of a tyrosine residue. Both GSTFs and GSTUs undergo changes in structure during catalysis indicative of an induced fit mechanism on substrate binding, with an understanding of plant GST structure/function allowing these proteins to be engineered for novel functions in detoxification and ligand recognition. Several major crops produce alternative thiols, with GSTUs shown to use homoglutathione in preference to glutathione, in herbicide detoxification reactions in soybeans. Similarly, hydroxymethylglutathione is used, in addition to glutathione in detoxifying the herbicide fenoxaprop in wheat. Following GST action, plants are able to rapidly process glutathione conjugates by at least two distinct pathways, with the available evidence suggesting these function in an organ- and species-specific manner. Roles for GSTs in endogenous metabolism are less well defined, with the enzymes linked to a diverse range of functions, including signaling, counteracting oxidative stress, and detoxifying and transporting secondary metabolites.
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Affiliation(s)
- Ian Cummins
- Center for Bioactive Chemistry, Durham University, Durham, United Kingdom
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8
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Liang B, Lu P, Li H, Li R, Li S, Huang X. Biodegradation of fomesafen by strain Lysinibacillus sp. ZB-1 isolated from soil. CHEMOSPHERE 2009; 77:1614-1619. [PMID: 19846192 DOI: 10.1016/j.chemosphere.2009.09.033] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 08/27/2009] [Accepted: 09/21/2009] [Indexed: 05/28/2023]
Abstract
The fomesafen degrading bacterium ZB-1 was isolated from contaminated agricultural soil, and identified as Lysinibacillus sp. based on the comparative analysis of 16S rRNA gene. The strain could utilize fomesafen as the sole carbon source for growth, and the total degradation rate was 81.32% after 7 d of inoculation in mineral salts medium. Strain ZB-1 could also degrade other diphenyl ethers including lactofen and fluoroglycofen. The optimum temperature for fomesafen degradation by strain ZB-1 was 30 degrees C. The effect of fomesafen concentration on degradation was also examined. Cell-free extract of strain ZB-1 was able to degrade fomesafen and other diphenyl ethers. Metabolism of fomesafen was accompanied by a transient accumulation of a metabolite identified as [N-[4-{4-(trifluoromethyl)phenoxy}-2-methanamidephenyl]acetamide] using liquid chromatography-mass spectrometry, thus indicating a metabolic pathway involving reduction, acetylation of nitro groups and dechlorination. The inoculation of strain ZB-1 to soil treated with fomesafen resulted in a higher degradation rate than in noninoculated soil regardless of the soil sterilized or nonsterilized.
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Affiliation(s)
- Bo Liang
- Key Laboratory for Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
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9
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Gorzerino C, Quemeneur A, Hillenweck A, Baradat M, Delous G, Ollitrault M, Azam D, Caquet T, Lagadic L. Effects of diquat and fomesafen applied alone and in combination with a nonylphenol polyethoxylate adjuvant on Lemna minor in aquatic indoor microcosms. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2009; 72:802-810. [PMID: 18951630 DOI: 10.1016/j.ecoenv.2008.08.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2008] [Revised: 08/26/2008] [Accepted: 08/28/2008] [Indexed: 05/27/2023]
Abstract
The influence of tank-mix adjuvants on pesticide toxicity remains largely unknown. Agral 90, a nonylphenol polyethoxylated tank-mix adjuvant, has been used with diquat (bipyridylium herbicide) and fomesafen (diphenyl-ether herbicide) in aquatic indoor microcosms in order to compare the toxicity of the single compounds and of binary herbicide-adjuvant mixtures to Lemna minor. Twenty-four microcosms were used and treatments were performed with substances alone or with herbicide-adjuvant binary mixtures, at two concentrations levels (44.4 and 222.2 microg/L for the herbicides, and 100 and 500 microg/L for Agral 90). Toxicity was assessed weekly for 1 month through growth measurements, as inferred from the relative frond number (RFN) and relative frond area (RFA). Concentrations of diquat and fomesafen in water and sediments were measured weekly. The herbicides showed very different behaviour in microcosms, with a rapid disappearance of diquat from the aqueous phase whereas fomesafen levels remained almost constant over time. Diquat strongly inhibited the growth of L. minor whereas fomesafen had no effect on plant growth. Presence of the adjuvant only slightly reduced the effect of the lowest concentration of diquat, probably as a result of dispersion of the herbicide at the water surface. It is concluded that tank-mix adjuvant designed to improve herbicide efficiency in the terrestrial environment did not have any effect on aquatic plants when applied to the aquatic environment.
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Affiliation(s)
- Caroline Gorzerino
- INRA, UMR Ecologie et Santé des Ecosystèmes, Equipe Ecotoxicologie et Qualité des Milieux Aquatiques, Agrocampus Rennes, 65 rue de Saint Brieuc, F-35042 Rennes, France
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10
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Farkas MH, Berry JO, Aga DS. Chlortetracycline detoxification in maize via induction of glutathione S-transferases after antibiotic exposure. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2007; 41:1450-6. [PMID: 17593756 DOI: 10.1021/es061651j] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Soil contamination with nonmetabolized antibiotics is an emerging environmental concern, especially on agricultural croplands that receive animal manure as fertilizer. In this study, phytotoxicity of chlortetracycline (CTC) antibiotics on pinto beans (Phaseolus vulgaris) and maize (Zea mays) was investigated under controlled conditions. When grown in CTC-treated soil, a significant increase in the activities of the plant stress proteins glutathione S-transferases (GST) and peroxidases (POX) were observed in maize plants, but not in pinto beans. In vitro conjugation reactions demonstrated that the induced GST in maize catalyzed the conjugation of glutathione (GSH) with CTC, producing stable conjugates that were structurally characterized using liquid chromatography/mass spectrometry. The antibiotic-induced GST produced CTC-glutathione conjugate at relative concentrations 2-fold higher than that produced by constitutively expressed GST extracted from untreated maize. On the other hand, GST extracted from pinto beans (both treated and untreated) did not efficiently catalyze glutathione conjugation with CTC. These results suggest that maize is able to detoxify chlortetracycline via the glutathione pathway, whereas pinto beans cannot. This may explain the observed stunted growth of pinto beans after antibiotic treatment. This study demonstrates the importance of plant uptake in determining the fate of antibiotics in soil and their potential phytotoxicity to susceptible plants.
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Affiliation(s)
- Michael H Farkas
- Department of Biological Sciences, University at Buffalo, Buffalo, New York 14260, USA
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Gershater M, Sharples K, Edwards R. Carboxylesterase activities toward pesticide esters in crops and weeds. PHYTOCHEMISTRY 2006; 67:2561-7. [PMID: 17078983 DOI: 10.1016/j.phytochem.2006.09.019] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Revised: 09/18/2006] [Accepted: 09/19/2006] [Indexed: 05/12/2023]
Abstract
Proteins were extracted from maize, rice, sorghum, soybean, flax and lucerne; the weeds Abutilon theophrasti, Echinochloa crus-galli, Phalaris canariensis, Setaria faberii, Setaria viridis, Sorghum halepense and the model plant Arabidopsis thaliana and assayed for carboxylesterase activity toward a range of xenobiotics. These included the pro-herbicidal esters clodinafop-propargyl, fenoxaprop-ethyl, fenthioprop-ethyl, methyl-2,4-dichlorophenoxyacetic acid (2,4-d-methyl), bromoxynil-octanoate, the herbicide-safener cloquintocet-mexyl and the pyrethroid insecticide permethrin. Highest activities were recorded with alpha-naphthyl acetate and methylumbelliferyl acetate. Esters of p-nitrophenol were also readily hydrolysed, with turnover declining as the chain length of the acyl component increased. Activities determined with model substrates were much higher than those observed with pesticide esters and were of limited value in predicting the relative rates of hydrolysis of the crop protection agents. Substrate preferences with the herbicides were typically 2,4-d-methyl>clodinafop-propargyl>fenthioprop-ethyl, fenoxaprop-ethyl and bromoxynil-octanoate. Isoelectric focussing in conjunction with staining for esterase activity using alpha-naphthyl acetate as substrate confirmed the presence of multiple carboxylesterase isoenzymes in each plant, with major qualitative differences observed between species. The presence of serine hydrolases among the resolved isoenzymes was confirmed through their selective inhibition by the organophosphate insecticide paraoxon. Our studies identify potentially exploitable differences between crops and weeds in their ability to bioactivate herbicides by enzymic hydrolysis and also highlight the usefulness of Arabidopsis as a plant model to study xenobiotic biotransformation.
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Affiliation(s)
- Markus Gershater
- Crop Protection Group, School of Biological and Biomedical Sciences, Durham University, Durham DH1 3LE, UK
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Abstract
Soluble plant glutathione transferases (GSTs) consist of seven distinct classes, six of which have been functionally characterized. The phi and tau class GSTs are specific to plants and the most numerous and abundant of these enzymes. Both have classic conjugating activities toward a diverse range of xenobiotics, including pesticides, where they are major determinants of herbicide selectivity in crops and weeds. In contrast, the zeta and theta class GSTs are conserved in animals and plants and have very restricted activities toward xenobiotics. Theta GSTs function as glutathione peroxidases, reducing organic hydroperoxides produced during oxidative stress. Zeta GSTs act as glutathione-dependent isomerases, catalyzing the conversion of maleylacetoacetate to fumarylacetoacetate, the penultimate step in tyrosine degradation. The other two classes of plant GSTs, the dehydroascorbate reductases (DHARs) and lambda GSTs, differ from phi, tau, zeta, and theta enzymes in being monomers rather than dimers and possessing a catalytic cysteine rather than serine in the active site. Both can function as thioltransferases, with the DHARs having a specialized function in reducing dehydroascorbate to ascorbic acid. The determination of the diverse plant-specific functions of the differing GST classes is described.
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Affiliation(s)
- Robert Edwards
- Centre for Bioactive Chemistry, School of Biological and Biomedical Sciences, Durham University, United Kingdom
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Skipsey M, Cummins I, Andrews CJ, Jepson I, Edwards R. Manipulation of plant tolerance to herbicides through co-ordinated metabolic engineering of a detoxifying glutathione transferase and thiol cosubstrate. PLANT BIOTECHNOLOGY JOURNAL 2005; 3:409-20. [PMID: 17173629 DOI: 10.1111/j.1467-7652.2005.00134.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The diphenyl ether herbicide fomesafen can be used selectively in soybean (Glycine max) due to its rapid detoxification by tau class glutathione transferases (GmGSTUs) which preferentially utilize the endogenous thiol homoglutathione (hGSH) as cosubstrate. Soybean cDNAs encoding GmGSTU21, which is highly active in detoxifying fomesafen, and an hGSH synthetase (GmhGS) have been cloned and functionally identified in Escherichia coli. Tobacco plants, which have limited GST activities towards fomesafen and which accumulate glutathione (GSH), rather than hGSH, have been transformed with either GmhGS alone, or a dual construct of GmhGS-GmGSTU21, both under the control of constitutive promoters. Using either construct, the transgenic tobacco accumulated hGSH, with a concomitant increase in GSH content. Segregating T1 plants were analysed for thiol content and GST activity towards fomesafen with GSH and hGSH as cosubstrates, and then scored for photobleaching injury caused by applications of fomesafen. These studies showed that hGSH accumulation alone gave no significant protection against the herbicide and that tolerance was only seen in plants which contained appreciable concentrations of hGSH and GmGSTU21 activity. Tolerance in the dual transformants was associated with the metabolism of radiolabelled fomesafen to inactive hGSH-derived conjugates, while susceptible lines were unable to detoxify the herbicide. These studies confirm the combined importance of specific GSTs and their preferred thiol cosubstrates in conferring herbicide selectivity traits in planta.
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Affiliation(s)
- Mark Skipsey
- Crop Protection Group, School of Biological and Biomedical Sciences, University of Durham, Durham DH1 3LE, UK
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Affiliation(s)
- Melinda Neal Martin
- Rutgers University, Center for Biotechnology and the Environment, New Brunswick, NJ 08901-8520, USA
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Flocco CG, Lindblom SD, Smits EAHP. Overexpression of enzymes involved in glutathione synthesis enhances tolerance to organic pollutants in Brassica juncea. INTERNATIONAL JOURNAL OF PHYTOREMEDIATION 2004; 6:289-304. [PMID: 15696703 DOI: 10.1080/16226510490888811] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Transgenic Indian mustard (Brassica juncea) overexpressing y-glutamylcysteine synthetase (ECS) or glutathione synthetase (GS) were shown previously to have two-fold higher levels of glutathione and total nonprotein thiols, as well as enhanced cadmium tolerance and accumulation. Here, the hypothesis was tested that these transgenics have enhanced tolerance to organic pollutants, based on the reasoning that many organic xenobiotics are detoxified via conjugation to glutathione. Both the ECS and GS transgenics showed enhanced tolerance to atrazine: while root growth of wildtype seedlings was inhibited 50% by 100 mg L(-1) atrazine, ECS and GS root growth was inhibited 20-30% (P < 0.05). The tolerance of the transgenics to CDNB (1-chloro-2,4-dinitrobenzene). metolachlor, and phenanthrene was also somewhat higher than wild type, but these differences were not as pronounced. Each of the organics treatments significantly enhanced total nonprotein thiol levels in all plant types (2 to 12-fold). Overall, these results suggest that GSH biosynthesis is limiting for atrazine detoxification in Indian mustard and that overexpression of enzymes involved in GSH biosynthesis offers a promising approach to create plants with the enhanced capacity to tolerate not only heavy metals, but also certain organics.
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Affiliation(s)
- Cecilia G Flocco
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
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16
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Edwards R, Dixon DP. Metabolism of Natural and Xenobiotic Substrates by the Plant Glutathione S-Transferase Superfamily. ECOLOGICAL STUDIES 2004. [DOI: 10.1007/978-3-662-08818-0_2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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17
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Dixon DP, McEwen AG, Lapthorn AJ, Edwards R. Forced evolution of a herbicide detoxifying glutathione transferase. J Biol Chem 2003; 278:23930-5. [PMID: 12692133 DOI: 10.1074/jbc.m303620200] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Plant Tau class glutathione transferases (GSTUs) detoxify diphenylether herbicides such as fluorodifen, determining their selectivity in crops and weeds. Using reconstructive PCR, a series of mutant GSTUs were generated from in vitro recombination and mutagenesis of the maize sequences ZmGSTU1 and ZmGSTU2 (with the prefix Zm designating Zea mays L.). A screen of 5000 mutant GSTUs identified seven enzymes with enhanced fluorodifen detoxifying activity. The best performing enhanced fluorodifen detoxifying mutant (EFD) had activity 19-fold higher than the parent enzymes, with a single point mutation conferring this enhancement. Further mutagenesis of this residue generated an EFD with a 29-fold higher catalytic efficiency toward fluorodifen as compared with the parents but with unaltered catalysis toward other substrates. When expressed in Arabidopsis thaliana, the optimized EFD, but not the parent enzymes, conferred enhanced tolerance to fluorodifen. Molecular modeling predicts that the serendipitous mutation giving the improvement in detoxification is due to the removal of an unfavorable interaction together with the introduction of a favorable change in conformation of residues 107-119, which contribute to herbicide binding.
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Affiliation(s)
- David P Dixon
- Crop Protection Group, School of Biological and Biomedical Sciences, University of Durham, South Road, Durham DH1 3LE, United Kingdom
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18
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Xu F, Lagudah ES, Moose SP, Riechers DE. Tandemly duplicated Safener-induced glutathione S-transferase genes from Triticum tauschii contribute to genome- and organ-specific expression in hexaploid wheat. PLANT PHYSIOLOGY 2002; 130:362-73. [PMID: 12226515 PMCID: PMC166568 DOI: 10.1104/pp.004796] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2002] [Revised: 04/16/2002] [Accepted: 05/20/2002] [Indexed: 05/20/2023]
Abstract
Glutathione S-transferase (GST) gene expression was examined in several Triticum species, differing in genome constitution and ploidy level, to determine genome contribution to GST expression in cultivated, hexaploid bread wheat (Triticum aestivum). Two tandemly duplicated tau class GST genes (TtGSTU1 and TtGSTU2) were isolated from a single bacterial artificial chromosome clone in a library constructed from the diploid wheat and D genome progenitor to cultivated wheat, Triticum tauschii. The genes are very similar in genomic structure and their encoded proteins are 95% identical. Gene-specific reverse transcriptase-polymerase chain reaction analysis revealed differential transcript accumulation of TtGSTU1 and TtGSTU2 in roots and shoots. Expression of both genes was induced by herbicide safeners, 2,4-dichlorophenoxyacetic acid and abscisic acid, in the shoots of T. tauschii; however, expression of TtGSTU1 was always higher than TtGSTU2. In untreated seedlings, TtGSTU1 was expressed in both shoots and roots, whereas TtGSTU2 expression was only detected in roots. RNA gel-blot analysis of ditelosomic, aneuploid lines that are deficient for 6AS, 6BS, or 6DS chromosome arms of cultivated, hexaploid bread wheat showed differential genome contribution to safener-induced GST expression in shoots compared with roots. The GST genes from the D genome of hexaploid wheat contribute most to safener-induced expression in the shoots, whereas GSTs from the B and D genomes contribute to safener-induced expression in the roots.
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MESH Headings
- 2,4-Dichlorophenoxyacetic Acid/pharmacology
- 5' Flanking Region/genetics
- Abscisic Acid/pharmacology
- Amino Acid Sequence
- Base Sequence
- Chromosomes, Artificial, Bacterial/genetics
- DNA, Plant/chemistry
- DNA, Plant/genetics
- Gene Duplication/drug effects
- Gene Expression Regulation, Enzymologic/drug effects
- Gene Expression Regulation, Plant/drug effects
- Glutathione Transferase/genetics
- Glutathione Transferase/metabolism
- Molecular Sequence Data
- Pesticides/pharmacology
- Plant Growth Regulators/pharmacology
- Plant Proteins/genetics
- Plant Proteins/metabolism
- Plant Roots/metabolism
- Plant Shoots/metabolism
- Polyploidy
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Sequence Homology, Nucleic Acid
- Species Specificity
- Substrate Specificity
- Tandem Repeat Sequences/genetics
- Triticum/drug effects
- Triticum/enzymology
- Triticum/genetics
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Affiliation(s)
- Fangxiu Xu
- Department of Crop Sciences, University of Illinois, Urbana, Illinois 61801, USA
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19
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Pflugmacher S, Schröder P, Sandermann H. Taxonomic distribution of plant glutathione S-transferases acting on xenobiotics. PHYTOCHEMISTRY 2000; 54:267-273. [PMID: 10870180 DOI: 10.1016/s0031-9422(00)00116-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Soluble and microsomal glutathione S-transferase activities for five model xenobiotics (nitrobenzene derivatives), two pesticidal xenobiotics (atrazine and fluorodifen), and a natural substrate (cinnamic acid), were determined in 59 different plant species and four plant cell suspension cultures. These enzyme activities were widely distributed over the plant kingdom with certain species showing particularly high activities. Marine macroalgae had a remarkably broad substrate range that included the substrates atrazine and fluorodifen. It is concluded that the evolutionary 'green liver' concept derived for xenobiotic metabolism in higher plant species is also valid for the constitutive soluble and microsomal glutathione S-transferases of lower plant species.
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Affiliation(s)
- S Pflugmacher
- GSF-Forschungszentrum für Umwelt und Gesundheit GmbH, Institut für Biochemische Pflanzenpathologie, Oberschleissheim, Germany
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20
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Skipsey M, Andrews CJ, Townson JK, Jepson I, Edwards R. Cloning and characterization of glyoxalase I from soybean. Arch Biochem Biophys 2000; 374:261-8. [PMID: 10666306 DOI: 10.1006/abbi.1999.1596] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glyoxalase I and glutathione transferase (GST) are two glutathione-dependent enzymes which are enhanced in plants during cell division and in response to diverse stress treatments. In soybean, a further connection between these two enzymes has been suggested by a clone (Accession No. X68819) resembling a GST being described as a glyoxalase I. To characterize glyoxalase I in soybean, GmGlyox I resembling the dimeric enzyme from animals has been cloned from a cDNA library prepared from soybean suspension cultures. When expressed in Escherichia coli, GmGlyox I was found to be a 38-kDa dimer composed of 21-kDa subunits and unlike the enzyme from mammals showed activity in the absence of metal ions. GmGlyox I was active toward the hemithioacetal adducts formed by reacting methylglyoxal, or phenylglyoxal, with glutathione, homoglutathione, or gamma-glutamylcysteine, showing no preference for homoglutathione adducts over glutathione adducts, even though homoglutathione is the dominant thiol in soybean. When the clone X68819 was expressed in E. coli, the respective recombinant enzyme was active as a GST rather than a glyoxalase and was termed GmGST 3. GmGST 3 was active as a homodimer (45 kDa) composed of 26-kDa subunits and showed a preference for glutathione over homoglutathione when conjugating 1-chloro-2,4-dinitrobenzene. Both enzymes are associated with cell division in soybean cultures, but GmGST 3 (0.4% total protein) was 40 times more abundant than GmGlyox I (0.01%).
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Affiliation(s)
- M Skipsey
- Department of Biological Sciences, University of Durham, Durham, DH1 3LE, UK
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21
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Reade JP, Cobb AH. Purification, characterization and comparison of glutathioneS-transferases from black-grass (Alopecurus myosuroidesHuds) biotypes. ACTA ACUST UNITED AC 1999. [DOI: 10.1002/(sici)1096-9063(199910)55:10<993::aid-ps56>3.0.co;2-j] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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22
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Hatton PJ, Cummins I, Price LJ, Cole DJ, Edwards R. Glutathione transferases and herbicide detoxification in suspension-cultured cells of giant foxtail (Setaria faberi). ACTA ACUST UNITED AC 1999. [DOI: 10.1002/(sici)1096-9063(199807)53:3<209::aid-ps762>3.0.co;2-m] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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Dixon DP, Cummins L, Cole DJ, Edwards R. Glutathione-mediated detoxification systems in plants. CURRENT OPINION IN PLANT BIOLOGY 1998; 1:258-66. [PMID: 10066594 DOI: 10.1016/s1369-5266(98)80114-3] [Citation(s) in RCA: 202] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Recent work has highlighted the presence of diverse glutathione-dependent enzymes in plants with potential roles in the detoxification of both xenobiotic and endogenous compounds. In particular, studies on glutathione transferases are further characterising their role in xenobiotic metabolism, and also raising intriguing possible roles in endogenous metabolism. The solution of their three-dimensional structures together with studies on their molecular diversity and substrate specificity is providing new insights into the function and classification of these enigmatic enzymes.
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Affiliation(s)
- D P Dixon
- Department of Biological Sciences, University of Durham, Durham DH1 3LE, UK
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