scholarly journals Protoporphyrinogen oxidase as a molecular target for diphenyl ether herbicides

1989 ◽  
Vol 260 (1) ◽  
pp. 231-235 ◽  
Author(s):  
M Matringe ◽  
J M Camadro ◽  
P Labbe ◽  
R Scalla
Keyword(s):  
Zea Mays ◽  
Solanum Tuberosum ◽  
Diphenyl Ether ◽  
Protoporphyrin Ix ◽  
Molecular Target ◽  
Plant Tissues ◽  
Mitochondrial Membranes ◽  
Protoporphyrinogen Oxidase ◽  
Cellular Target

Diphenyl ether herbicides induce an accumulation of protoporphyrin IX in plant tissues. By analogy to human porphyria, the accumulation could be attributed to decreased (Mg or Fe)-chelatase or protoporphyrinogen oxidase activities. Possible effects of acifluorfen-methyl on these enzymes were investigated in isolated corn (maize, Zea mays) etioplasts, potato (Solanum tuberosum) and mouse mitochondria, and yeast mitochondrial membranes. Acifluorfen-methyl was strongly inhibitory to protoporphyrinogen oxidase activities whatever their origins [concn. causing 50% inhibition (IC50) = 4 nM for the corn etioplast enzyme]. By contrast, it was roughly 100,000 times less active on (Mg or Fe)-chelatase activities (IC50 = 80-100 microM). Our results lead us to propose protoporphyrinogen oxidase as a cellular target for diphenyl ether herbicides.

Molecular Aspects of Herbicide Action on Protoporphyrinogen Oxidase

1993 ◽  
Vol 48 (3-4) ◽  
pp. 326-333 ◽  
Author(s):  
Beate Nicolaus ◽  
Gerhard Sandmann ◽  
Peter Böger
Keyword(s):  
Diphenyl Ether ◽  
Protoporphyrin Ix ◽  
Protoporphyrinogen Oxidase ◽  
Relative Specificity ◽  
Oxidase Inhibition ◽  
Dilution Experiments ◽  
Membrane Bound ◽  
The Common ◽  
Molecular Aspects ◽  
Derivatives Of

Abstract Protoporphyrinogen oxidase, the last enzyme of the common tetrapyrrole biosynthetic pathway, is inhibited by several peroxidizing compounds resulting in accumulation of photodynamic tetrapyrroles, mainly protoporphyrin IX. The inhibition characteristics of two chemi­cally unrelated compounds were studied using membrane bound protoporphyrinogen oxidase from corn etioplasts. As shown by Lineweaver-Burk-analysis, the inhibition of enzyme activity by the diphenyl ether oxyfluorfen and the cyclic imide MCI 15 are competitive with respect to the substrate. The competitive interaction of protoporphyrinogen and the two chemically un­related inhibitors indicate a relative specificity of the binding site. The reversibility of oxyfluorfen inhibition was evaluated by dilution experiments and was shown to be independent of the presence of DTT. The analysis of structure-activity-relationship on protoporphyrinogen oxidase inhibition was investigated with para-substituted derivatives of phenyl-3,4,5,6-tetrahydro-phthalimides. The results obtained by QSAR -calculation yielded a good correlation of the inhibitory activity determined by the lipophilicity of the para-substituent. These data point to one binding region of the inhibitors within a lipophilic environment associated with the active center of the enzyme.

Isolation and Characterization of a Chlamydomonas reinhardtii Mutant Resistant to Photobleaching Herbicides

1993 ◽  
Vol 48 (3-4) ◽  
pp. 339-344 ◽  
Author(s):  
Hiromichi Oshio ◽  
Hideyuki Shibata ◽  
Nobuaki Mito ◽  
Masako Yamamoto ◽  
Elizabeth H. Harris ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Oxidase Activity ◽  
Higher Plants ◽  
Diphenyl Ether ◽  
Protoporphyrin Ix ◽  
Nuclear Genome ◽  
Photosynthetic Electron Transport ◽  
Wild Type ◽  
Protoporphyrinogen Oxidase ◽  
Isolation And Characterization

A group of highly active N -phenylimide photobleaching herbicides have been synthesized. These N -phenylimide herbicides as well as diphenyl ether herbicides induce protoporphyrin IX accumulation and inhibit protoporphyrinogen oxidase activity at extremely low concentrations in higher plants. The binding of a 14C -labeled N -phenylimide herbicide S-23121 [N-[4-chloro- 2-fluoro-5-[(1-m ethyl-2-propynyl)oxy]phenyl]-3,4,5,6-tetrahydrophthalimide] to the solubilized plastid fractions of greening corn seedlings is competed by the diphenyl ether herbicide acifluorfen-ethyl, but not by diuron, an inhibitor of photosynthetic electron transport. These results indicate a similar mode of action for both N -phenylimide and diphenyl ether herbicides.In order to investigate the mechanism of photobleaching herbicides at the molecular level, a strain of Chlamydomonas reinhardtii RS-3 resistant to N -phenylimide S-23142 [N -(4-chloro- 2-fluoro-5-propargyloxyphenyl)-3,4,5,6-tetrahydrophthalimide] was isolated by mutagenesis with N -m ethyl-N′-nitro-N -nitrosoguanidine. The 90% inhibition concentration of N -phenylimide S-23142 for growth of RS-3 was 100 times higher than that for wild type. Maximum accumulation of protoporphyrin IX was reached at 0.03 μᴍ of S-23142 for the wild type and 3 μᴍ for RS-3. RS-3 was resistant to oxadiazon, oxyfluorfen and acifluorfen-ethyl which had been shown to have the same mechanism of action as N -phenylimide herbicides, but not to paraquat, diuron or fluridone. Genetic analysis of RS-3 strain showed that the resistance results from a dominant mutation ( rs-3) in the nuclear genome. The magnesium protoporphyrin IX synthesizing activity from 5-am inolevulinic acid in chloroplast fragments isolated from RS-3 was less sensitive to S-23142 than that from wild type (CC-407). Protoporphyrinogen oxidase activity in Percoll™ -purified chloroplasts from RS-3 was also less sensitive to S-23142 than that from wild type. These results indicate that the resistance of RS-3 is specific for photobleaching herbicides, and that the mutation is related to protoporphyrinogen oxidase, the primary site of the photobleaching herbicide action.

scholarly journals Kinetic studies on protoporphyrinogen oxidase inhibition by diphenyl ether herbicides

1991 ◽  
Vol 277 (1) ◽  
pp. 17-21 ◽  
Author(s):  
J M Camadro ◽  
M Matringe ◽  
R Scalla ◽  
P Labbe
Keyword(s):  
Methyl Ester ◽  
Diphenyl Ether ◽  
Kinetic Studies ◽  
Inhibition Kinetics ◽  
Mitochondrial Membranes ◽  
Protoporphyrinogen Oxidase ◽  
Nitrobenzoic Acid ◽  
Diphenyl Ethers ◽  
Oxidase Inhibition ◽  
Kinetics Of

Diphenyl ethers (DPEs) and related herbicides are powerful inhibitors of protoporphyrinogen oxidase, an enzyme involved in the biosynthesis of haems and chlorophylls. The inhibition kinetics of protoporphyrinogen oxidase of various origins by four DPEs, (methyl)-5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid (acifluorfen and its methyl ester, acifluorfen-methyl), methyl-5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-chlorobenzoate (LS 820340) and methyl-5-[2-chloro-5-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid (RH 5348), were studied. The inhibitions of the enzymes from maize (Zea mays) mitochondrial and etiochloroplastic membranes and mouse liver mitochondrial membranes were competitive with respect to the substrate, protoporphyrinogen IX, for all four molecules. The relative efficiencies of the inhibitors were: acifluorfen-methyl greater than LS 820340 much greater than RH 5348 greater than or equal to acifluorfen. The four molecules showed mixed-competitive type inhibition of the enzyme from yeast mitochondria where acifluorfen, a carboxylic acid, had the same inhibitory activity as its methyl ester, acifluorfen-methyl, and both were much greater than that of LS 820340 and RH 5348.

scholarly journals PPO-Inhibiting Herbicides and Structurally Relevant Schiff Bases: Evaluation of Inhibitory Activities against Human Protoporphyrinogen Oxidase

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 383
Author(s):  
Milan Jakubek ◽  
Michal Masařík ◽  
Tomáš Bříza ◽  
Robert Kaplánek ◽  
Kateřina Veselá ◽  
...  
Keyword(s):  
Melting Temperature ◽  
Schiff Bases ◽  
Anticancer Agents ◽  
Protoporphyrin Ix ◽  
Docking Study ◽  
Structural Motif ◽  
Protoporphyrinogen Oxidase ◽  
Ic50 Values ◽  
Inhibitory Activities ◽  
Potential Inhibitors

The study of human protoporphyrinogen oxidase (hPPO) inhibition can contribute significantly to a better understanding of some pathogeneses (e.g., porphyria, herbicide exposure) and the development of anticancer agents. Therefore, we prepared new potential inhibitors with Schiff base structural motifs (2-hydroxybenzaldehyde-based Schiff bases 9–13 and chromanone derivatives 17–19) as structurally relevant to PPO herbicides. The inhibitory activities (represented by the half maximal inhibitory concentration (IC50) values) and enzymatic interactions (represented by the hPPO melting temperatures) of these synthetic compounds and commercial PPO herbicides used against hPPO were studied by a protoporphyrin IX fluorescence assay. In the case of PPO herbicides, significant hPPO inhibition and changes in melting temperature were observed for oxyfluorten, oxadiazon, lactofen, butafenacil, saflufenacil, oxadiargyl, chlornitrofen, and especially fomesafen. Nevertheless, the prepared compounds did not display significant inhibitory activity or changes in the hPPO melting temperature. However, a designed model of hPPO inhibitors based on the determined IC50 values and a docking study (by using AutoDock) found important parts of the herbicide structural motif for hPPO inhibition. This model could be used to better predict PPO herbicidal toxicity and improve the design of synthetic inhibitors.

scholarly journals Dinámica de la biomasa microbiana y su relación con la respiración y el nitrógeno del suelo en tierras agrícolas en el valle del Mantaro

2016 ◽  
Vol 16 (1) ◽  
pp. 17
Author(s):  
Amanda Hinostroza ◽  
Julio Malca ◽  
Luis Suárez
Keyword(s):  
Zea Mays ◽  
Solanum Tuberosum ◽  
Santa Ana

Se estudió el efecto del abonamiento orgánico con estiércol de ganado vacuno, ovino, de cuy, fertilización química y sin abonamiento sobre la variación del nitrógeno, variación de la biomasa microbiana del suelo y la respiración del suelo en cultivos de papa (Solanum tuberosum) y maíz (Zea mays) durante la campaña agrícola 2009 en cuatro localidades del valle del Mantaro: El Mantaro, Chupaca, Santa Ana y Huayao, bajo diseño experimental de bloques completamente aleatorios con arreglo factorial. La biomasamicrobiana se cuantificó mediante el método de fumigación – extracción, y la respiración basal del suelo (RB) se determinó mediante incubación. Los resultados indican tendencia polinomial cúbica en la variación del nitrógeno, mostrando una continua disminución hacia los 60 días y un ligero ascenso hacia los 90 días.De otro lado no, existe una relación definida entre la biomasa microbiana y la respiración del suelo. Se han determinado valores de RB desde 0,02 a 3,26y desde 0,14 a 2,34 mg CO2/ha/h en cultivos de papa y maíz, respectivamente; valores que indican actividad microbiológica de muy baja a media en la mayoría de suelos y tratamientos, presentándose la mayor tasa de respiración durante el mes de diciembre, periodo con mayor temperatura en el suelo con respecto a los meses de febrero y marzo, esto comprueba que a mayor temperatura mayor respiración basal.Palabras clave: Biomasa microbiana del suelo. Respiración del suelo. Nitrógeno en el suelo. Valle delMantaro.DOI: http://dx.doi.org/10.21503/CienciayDesarrollo.2013.v16i1.02

Synchytrium endobioticum. [Descriptions of Fungi and Bacteria].

1983 ◽  
Author(s):  
J. C. Walker
Keyword(s):  
Solanum Tuberosum ◽  
Geographical Distribution ◽  
Plant Tissues ◽  
Wart Disease ◽  
Synchytrium Endobioticum ◽  
Potato Wart Disease ◽  
Water Films ◽  
Resting Spores ◽  
America South ◽  
Local Dispersal

Abstract A description is provided for Synchytrium endobioticum. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Solanaceae (potato, Solanum tuberosum). Other plants infected experimentally include several species of Solanum (Karling, 1964), Petunia and Nicotiana spp. (53, 4566), Lycopersicon esculentum, Physalis and Capsicastrum spp. (59, 416). DISEASE: Potato wart disease, causing dark brown warty cauliflower-like excrescences of infected tubers, which decay to release golden-brown resting spores. On aerial shoots green galls may develop, composed of convoluted masses of tissue. GEOGRAPHICAL DISTRIBUTION: Africa, Asia, Europe, North America, South America (CMI Map 1, ed. 5, 1972). TRANSMISSION: By the movement of infected soil or plant tissues. Local dispersal by zoospores swimming in water films may also occur.

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