Mode of Action of Novel 2-(Benzylamino)-4-methyl-6-(trifluoro- methyl)-1,3,5-triazine Herbicides:  Inhibition of Photosynthetic Electron Transport and Binding Studies

1999 ◽  
Vol 47 (10) ◽  
pp. 4398-4402 ◽  
Author(s):  
Aiko Ohki ◽  
Nobuhiro Kuboyama ◽  
Kazuya Koizumi ◽  
Akira Tanaka ◽  
Yukiharu Sato ◽  
...  
Keyword(s):  
Electron Transport ◽  
Mode Of Action ◽  
Photosynthetic Electron Transport ◽  
Triazine Herbicides ◽  
Binding Studies

Metribuzin-Resistant Mutants of Chlamydomonas reinhardii

1984 ◽  
Vol 39 (5) ◽  
pp. 437-439 ◽  
Author(s):  
N. Pucheu ◽  
W. Oettmeier ◽  
U. Heisterkamp ◽  
K. Masson ◽  
G.F. Wildner
Keyword(s):  
Electron Transport ◽  
Photosynthetic Electron Transport ◽  
Wild Type ◽  
Binding Studies ◽  
Molecular Weight Range ◽  
Chlamydomonas Reinhardii ◽  
Thylakoid Membrane Proteins ◽  
Mutant Strains ◽  
Resistant Mutants

Herbicide resistance in Chlamydomonas reinhardii cells was induced by mutagenesis with 5-fluorodeoxyuridine and ethylmethanesulfonate. Four mutant strains were isolated and analyzed for resistance against DCMU-type or phenolic inhibitors of photosynthetic electron transport. The mutants were different in both the extent and the pattern of their resistance: the R/S value, i.e. the ratio of I50 values of the inhibition of photosynthetic electron transport in isolated resistant and susceptible thylakoids, varied for metribuzin from 10 000 to 36. The mutant MZ-1 was resistant against metribuzin, atrazine and DCMU, whereas the mutant MZ-2 showed resistance mainly against metribuzin and atrazine. The mutant MZ-3 was similar to MZ-1, but showed a lesser extent of resistance against DCMU. The mutant MZ-4 showed resistance against metribuzin, but not against atrazine. These results demonstrate that the resistance against one herbicide of the DCMU-type (metribuzin) must not be accompanied by similar resistance against te other inhibitors. Binding studies with radioactively labeled herbicides, [14C]metribuzin, [14C]atrazine and [3H]DCMU, and isolated thylakoids supported these observations. Phosphorylation of thylakoid membrane proteins was studied with wild-type cells and resistant mutants under in vivo conditions in the light. The 32P-labeled main proteins bands were in the molecular weight range of 10-14 kDa, 26-29 kDa, 32-35 kDa and 46-48 kDa. The pattern and the extent of incorporation of 32P were similar for the mutants and the wild-type cells.

Inhibition of Photosynthetic Electron Transport by the Quinone Antagonist UHDBT

1981 ◽  
Vol 36 (3-4) ◽  
pp. 272-275 ◽  
Author(s):  
Walter Oettmeier ◽  
Klaus Masson ◽  
Doris Godde
Keyword(s):  
Electron Transport ◽  
Green Alga ◽  
Photosynthetic Electron Transport ◽  
Binding Studies ◽  
Chlamydomonas Reinhardii ◽  
Efficient Inhibitor ◽  
Low Concentrations

UHDBT (5-n-undecyl-6-hydroxy-4,7-dioxobenzothiazole) is an efficient inhibitor of photosynthetic electron transport in chloroplasts from spinach (pI50-value = 7.61) and the green alga Chlamydomonas reinhardii. At low concentrations of UHDBT its site of inhibition is located at the reducing side of plastoquinone, identical to that of 3-(3,4-dichlorophenyl)-1, 1-dimethylurea (DCMU). This became evident from functional as well as binding studies. At higher concentrations of UHDBT a secondary inhibition site at the oxidizing side of plastoquinone, identical to that of 2,5-dibromo-3-methyl-6-isopropyl-1,4-benzoquinone (DBMIB) becomes evident

scholarly journals Photosynthetic Electron Transport Inhibition by 2-Substituted 4-Alkyl-6-benzylamino-1,3,5-triazines with Thylakoids from Wild-Type and Atrazine-Resistant Chenopodium album

2002 ◽  
Vol 57 (11-12) ◽  
pp. 1009-1015 ◽  
Author(s):  
Ruiko Okano ◽  
Aiko Ohki ◽  
Shinpei Ohki ◽  
Hitoshi Kohno ◽  
Jack J. S. van Rensen ◽  
...  
Keyword(s):  
Electron Transport ◽  
Chenopodium Album ◽  
Photosynthetic Electron Transport ◽  
Resistance Ratio ◽  
Triazine Herbicides ◽  
Inhibition Assay ◽  
Wild Type ◽  
Amino Groups ◽  
Triazine Derivatives ◽  
Derivatives Of

The effect of 2-benzylamino-1,3,5-triazines on photosynthetic electron transport (PET) was measured with thylakoids isolated from atrazine-resistant, wild-type Chenopodium album, and spinach to find novel 1,3,5-triazine herbicides bearing a strong PET inhibition. The PET inhibition assay with Chenopodium (wild-type and resistant), yielded a resistance ratio (R/ W = I50 (resistant)/I50 (wild-type)) of 324 for atrazine while for benzylamino-1,3,5-triazine derivatives of diamino-1,3,5-triazines a R/W of 11 to 160 was found. The compounds having a benzylamino group at one of the amino groups in the diamino-1,3,5-triazines have a resistant ratio down to one half to 1/30 of the atrazine value. The average resistance ratio of 21 benzylamino derivatives of monoamino-1,3,5-triazines was found to be about 4.0. The inhibition of 21 benzylamino-1,3,5-triazines assayed with atrazine-resistant Chenopodium thylakoids, indicated by pI50 (R) -values, correlated well with the PET inhibition pI50 (W) of wildtype thylakoids from Chenopodium.

Resistance to Triazine Herbicides in Horseweed (Conyza canadensis)

Weed Science ◽  
1984 ◽  
Vol 32 (5) ◽  
pp. 669-674 ◽  
Author(s):  
Endre Lehoczki ◽  
Gábor Laskay ◽  
Endre Pölös ◽  
József Mikulás
Keyword(s):  
Electron Transport ◽  
Lipid Content ◽  
Marked Reduction ◽  
Photosynthetic Electron Transport ◽  
Photosynthetic Characteristics ◽  
Resistance Factor ◽  
Conyza Canadensis ◽  
Triazine Herbicides ◽  
Chloroplast Membranes ◽  
Atrazine Resistance

Insensitivity to atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] and certain other herbicides was found in plants of horseweed (Conyza canadensis(L.) Crong. ♯4ERICA) collected from vineyards where atrazine had been applied extensively. There were no differences in the uptake, translocation, or accumulation of radiolabeled atrazine between plants of the susceptible and resistant biotypes. However, atrazine at 1 × 10-4M caused no inhibition of photosynthetic electron transport in resistant leaves. Photosynthetic characteristics of leaves of susceptible and resistant plants showed different sensitivities to atrazine, but similar sensitivities to diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] and ioxynil (4-hydroxy-3,5-diiodobenzonitrile). Isolated chloroplast membranes from resistant plants exhibited a resistance factor of 1000 to atrazine but only 10 to 30 to methylthio-s-triazines. DNOC (4,6-dinitro-o-cresol) was found to be more effective in susceptible chloroplasts than in resistant ones. A marked reduction in the galactolipid content, especially digalactosyl diglyceride, was found in resistant leaves. It is suggested that these alterations in lipid content and composition may contribute to atrazine resistance in horseweed.

Superoxide-and Ethane-Formation in Subchloroplast Particles: Catalysis by Pyridinium Derivatives

1980 ◽  
Vol 35 (9-10) ◽  
pp. 770-775 ◽  
Author(s):  
E. F. Elstner ◽  
H. P. Fischer ◽  
W. Osswald ◽  
G. Kwiatkowski
Keyword(s):  
Electron Transport ◽  
Photosystem I ◽  
Photosynthetic Electron Transport ◽  
Redox Potentials ◽  
Light Reaction ◽  
Pyridinium Bromide ◽  
Superoxide Formation ◽  
Fatty Acid Peroxidation ◽  
Chlorophyll Bleaching ◽  
Ethane Formation

Abstract Oxygen reduction by chloroplast lamellae is catalyzed by low potential redox dyes with E′0 values between -0 .3 8 V and -0 .6 V. Compounds of E′0 values of -0 .6 7 V and lower are inactive. In subchloroplast particles with an active photosystem I but devoid of photosynthetic electron transport between the two photosystems, the active redox compounds enhance chlorophyll bleaching, superoxide formation and ethane production independent on exogenous substrates or electron donors. The activities of these compounds decrease with decreasing redox potential, with one exception: 1-methyl-4,4′-bipyridini urn bromide with an E′0 value of lower -1 V (and thus no electron acceptor of photosystem I in chloroplast lamellae with intact electron transport) stimulates light dependent superoxide formation and unsaturated fatty acid peroxidation in sub­ chloroplast particles, maximal rates appearing after almost complete chlorophyll bleaching. Since this activity is not visible with compounds with redox potentials below -0 .6 V lacking the nitrogen atom at the 1-position of the pyridinium substituent, we assume that 1 -methyl-4,4′-bi-pyridinium bromide is “activated” by a yet unknown light reaction.

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