Effect of different photosystem II inhibitors on chloroplasts isolated from species either susceptible or resistant toward s-triazine herbicides

Oettmeier, Walter; Masson, Klaus; Fedtke, Carl; Konze, Jörg R.; Schmidt, Robert R.

doi:10.1016/0048-3575(82)90077-3

Cited by 59 publications

(46 citation statements)

References 22 publications

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“…However, mutants of higher plants resistant to atrazine but still DCMU sensitive have been characterized by two different groups [24,26]. We have also selected several mutants resistant to one herbicide and sensitive to the other [25].…”

Section: Photosynthesismentioning

confidence: 99%

Evidence for different binding sites on the 33‐kDa protein for DCMU, atrazine and Q_B

1984

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Two DCMU-resistant strains of the cyanobacterium Synechocystis 6714 were used to analyse the binding sites of DCMU, atrazine and QB. DCMU'-11~ was DCMU and atrazine resistant; it presented an impaired electron flow and its 33-kDa protein was weakly attached to the membrane. DCMU'-IIB, derived from the former, simultaneously regained atrazine sensitivity, normal electron flow and a tight linkage of the 33-kDa protein to the membrane. This mutant shows that loss of DCMU binding does not necessarily affect the binding of either atrazine or QB. The role of the 33-kDa protein is discussed. Cyanobacteria Mutant Herbicide

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Section: Photosynthesismentioning

confidence: 99%

Evidence for different binding sites on the 33‐kDa protein for DCMU, atrazine and Q_B

1984

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“…But, all resistant plants have not been determined to have the mutation from serine to glycine, so naturally occurring serine to threonine mutants are possible. Some mutant plants have been reported to be resistant to substituted ureas, especially methoxyaminotype ureas (22,25). These biotypes may have the Thr-264 mutation.…”

Section: Discussionmentioning

confidence: 99%

The Mechanism of Herbicide Resistance in Tobacco Cells with a New Mutation in the Q_B Protein

Sigematsu¹,

Sato²,

Yamada³

1989

Plant Physiol.

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A new mutant of the psbA gene conferring resistance to 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) was obtained by selection of photomixotrophic tobacco (Nkotiana tabacum cv Samsun NN) cells. The 264th codon AGT (serine) in the wild psbA gene was changed to ACT (threonine) in these mutant tobacco cells. All other higher plants resistant to atrazine exhibit a change to GGT (glycine) in this codon. Measurements of Hill reaction activity and chlorophyll fluorescence showed that the threonine 264-containing plastoquinone serving as secondary stable electron acceptor of PSII (QB protein) had not only strong resistance to triazine-type herbicides but also moderate resistance to substituted urea-type herbicides. Threonine-type QB protein showed especially strong resistance to methoxylamino derivatives of the substituted urea herbicides. The projected secondary structures of the mutant Q5 proteins indicate that the crossresistance of threonine 264 QB protein to triazine and urea herbicides is mainly due to a conformational change of the binding site for the herbicides. However, the glycine 264 Os protein is resistant to only triazine herbicides because of the absence of an hydroxyl group and not because of a conformational change.Photosystem II (PSII) complex has the important function of splitting water to form molecular oxygen in photosynthesis. Among the components of the PSII complex, the 32 kD polypeptide (known as the QB3 or Dl protein) has a special importance since it forms part of the reaction center which transports electrons from the primary electron acceptor, QA, to the secondary stable electron acceptor, QB (20). The QB protein is also important as the primary target site of many herbicides which act by inhibiting photosynthesis (triazines, substituted ureas, triazinones, uracils and so on) (9, 24).The amino acid sequence ofthe QB protein was determined from the sequence ofthe psbA gene which encodes this protein (11,13, 33). The 3-dimensional structure of the QB protein, however, has not been determined since it is extremely unstable in the isolated state. Thus, the mechanisms of electron transport and herbicide-binding in PSII are not fully under-'

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“…That is, there are apparently 20% more DCMU-binding sites than atrazine-binding sites in spinach thylakoids. Oettmeier et al (1982) also reported that DCMU-binding sites exceeded atrazine-binding sites in Arnarantkus retroflexus by 12%.…”

Section: K~ = Kd (1 + [T]/ki)mentioning

confidence: 99%

“…Using radioactively-labelled herbicides, it has been shown (Tischer and Strotmann 1977;Oettmeier et al 1982) that herbicide binding was directly related to the inhibition of linear electron transport. Herbicide-binding is usually analysed by a plot of the reciprocal of bound herbicide, Cb (mol Chl/mol) vs. the reciprocal of free herbicide concentration, Cf (M-~), which gives for a singlespecies of binding site a straight line of the form: 1/Cb = 1/Cb .... -I-(Kd/C b .... )'(l/Of) where Cb .... is the maximum number of binding sites, obtained from the intercept, and Kd is the dissociation constant of the herbicide-PSII complex, and is inversely related to the affinity of the binding sites.…”

Section: Introductionmentioning

confidence: 99%

“…Herbicide-binding is usually analysed by a plot of the reciprocal of bound herbicide, Cb (mol Chl/mol) vs. the reciprocal of free herbicide concentration, Cf (M-~), which gives for a singlespecies of binding site a straight line of the form: 1/Cb = 1/Cb .... -I-(Kd/C b .... )'(l/Of) where Cb .... is the maximum number of binding sites, obtained from the intercept, and Kd is the dissociation constant of the herbicide-PSII complex, and is inversely related to the affinity of the binding sites. Occasionally, a marked deviation from a straight line is evident at high concentrations of atrazine (Tischer and Strotmann 1977;Jursinic and Stemler 1983), diuron (Oettmeier et al 1982) or phenmedipham (Tischer and Strotmann 1977). Initially, the downward deviation from a straight line obtained with high concentrations of herbicide was attributed to non-specific binding to thylakoid membranes (Tischer and Strotmann 1977;Laasch et al 1981).…”

Section: Introductionmentioning

confidence: 99%

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A reassessment of the use of herbicide binding to measure photosystem II reaction centres in plant thylakoids

1990

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The binding of the herbicide atrazine to thylakoid membranes is often used to quantify Photosystem II reaction centres. Two atrazine binding sites, with high and low affinities, have been observed on the D1 and D2 polypeptides of Photosystem II, respectively (McCarthy S., Jursinic P. and Stemler A. (1988) Plant Physiol. 86S:46). We have observed that the accessibility of the low-affinity binding sites is variable, being limited in freshly isolated thylakoids or in fresh frozen-thawed thylakoids, but increasing during storage of the membranes on ice. In contrast, the accessibility of the high-affinity binding sites, which are titratable at low concentrations (< 500 nM) of herbicide, is much less variable, although the dissociation constant is greatly influenced by ethanol. We conclude that to quantify Photosystem II reaction centres by atrazine binding, it is sufficient and more reliable to assay only the high-affinity binding sites.

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Effect of different photosystem II inhibitors on chloroplasts isolated from species either susceptible or resistant toward s-triazine herbicides

Cited by 59 publications

References 22 publications

Evidence for different binding sites on the 33‐kDa protein for DCMU, atrazine and Q_B

Evidence for different binding sites on the 33‐kDa protein for DCMU, atrazine and Q_B

The Mechanism of Herbicide Resistance in Tobacco Cells with a New Mutation in the Q_B Protein

A reassessment of the use of herbicide binding to measure photosystem II reaction centres in plant thylakoids

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Effect of different photosystem II inhibitors on chloroplasts isolated from species either susceptible or resistant toward s-triazine herbicides

Cited by 59 publications

References 22 publications

Evidence for different binding sites on the 33‐kDa protein for DCMU, atrazine and QB

Evidence for different binding sites on the 33‐kDa protein for DCMU, atrazine and QB

The Mechanism of Herbicide Resistance in Tobacco Cells with a New Mutation in the QB Protein

A reassessment of the use of herbicide binding to measure photosystem II reaction centres in plant thylakoids

Contact Info

Product

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Evidence for different binding sites on the 33‐kDa protein for DCMU, atrazine and Q_B

Evidence for different binding sites on the 33‐kDa protein for DCMU, atrazine and Q_B

The Mechanism of Herbicide Resistance in Tobacco Cells with a New Mutation in the Q_B Protein