Purification and characterization of a safener‐induced glutathione S‐transferase from wheat (<i>Triticum aestivum</i>)

Pascal, Sophie; Scalla, René

doi:10.1034/j.1399-3054.1999.106103.x

Cited by 47 publications

(44 citation statements)

References 55 publications

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“…Upon treatment of grass crops with safeners, GSTs able to conjugate these herbicides are induced predominantly in shoot tissues. This response is associated with a high level of protection against herbicide damage in maize (Irzyk and Fuerst, 1993;Holt et al, 1995;Dixon et al, 1998), wheat Riechers et al, 1997;Pascal and Scalla, 1999;Xu et al, 2002), rice Hatzios, 2002a, 2002b), and sorghum (Dean et al, 1990;Gronwald and Plaisance, 1998).…”

Section: Discussionmentioning

confidence: 99%

“…It is thought that safeners reduce herbicide toxicity in crops by inducing the expression of GSTs capable of conjugating the herbicide to GSH. GST-mediated metabolism of herbicides in maize (Zea mays; Dixon et al, 1997aDixon et al, , 1997b, sorghum (Sorghum bicolor; Gronwald and Plaisance, 1998), wheat (Triticum aestivum; Cummins et al, 1997;Pascal and Scalla, 1999), rice (Oryza sativa; Wu et al, 1999;Hatzios, 2002a, 2002b), and barley (Hordeum vulgare; Scalla and Roulet, 2002) can be selectively increased by treatment with herbicide safeners. The utility of safeners in agriculture depends on them not enhancing herbicide tolerance in target weeds.…”

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confidence: 99%

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Organ-Specific Expression of Glutathione S-Transferases and the Efficacy of Herbicide Safeners in Arabidopsis

DeRidder

Goldsbrough

2005

Plant Physiology

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The functions of plant glutathione S-transferases (GSTs) under normal growth conditions are poorly understood, but their activity as detoxification enzymes has been harnessed in agriculture for selective weed control. Herbicide safeners protect monocot crops from herbicide injury but have little effect on weedy monocot or dicot species. Protection by safeners is associated with expression of herbicide-metabolizing enzymes including GSTs, but the basis for selective action of safeners between monocots and dicots is not known. To address this question we have studied the response of Arabidopsis (Arabidopsis thaliana) to various safeners. Benoxacor, fenclorim, and fluxofenim did not protect Arabidopsis from herbicide injury but did induce RNA expression of the glutathione-conjugate transporters encoded by AtMRP1, AtMRP2, AtMRP3, and AtMRP4. These safeners also induced the organ-specific expression of AtGSTU19 and AtGSTF2, two previously characterized Arabidopsis GSTs from different classes of this enzyme family. RNA hybridization, immunoblot, and reporter gene analyses indicated expression of AtGSTU19 induced by safeners predominated in roots. To test the hypothesis that increased expression of AtGSTU19 would be sufficient to provide tolerance to chloroacetamide herbicides, a chimeric gene was produced containing the open reading frame for this GST driven by a constitutive promoter. Plants containing this transgene had a modest increase in AtGSTU19 protein, predominantly in roots, but this had no effect on tolerance to chloroacetamide herbicides. The localized induction of GSTs by safeners in roots of Arabidopsis may explain why these compounds are unable to provide herbicide tolerance to dicot plant species.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Organ-Specific Expression of Glutathione S-Transferases and the Efficacy of Herbicide Safeners in Arabidopsis

DeRidder

Goldsbrough

2005

Plant Physiology

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“…Marrs (1996) suggested that, in plants, a common effect of heavy metals, pathogen attack and/or wounding would be the generation of reactive oxygen species and that GSTs are induced in response to oxidative stress to protect cellular compounds from damage. Pascal & Scalla (1999) hypothesized that GSTs can function in plants like glutathione peroxidases, which are major mechanisms of antioxidant defense. In a general manner, Vangronsveld et al (1997) suggested that the induction of antioxidative enzymes is an indirect effect of metal toxicity.…”

Section: Materials and Methods Collectionmentioning

confidence: 99%

Effects of mercury on antioxidant mechanisms in the marine phanerogam Posidonia oceanica

et al. 2002

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“…This enhancement is selective, with the specific GST isoenzymes induced depending on the safener used. For example, treatment of wheat with naphthalic anhydride resulted in the induction of the phi class TaGST2-3, which detoxifies the herbicide fluorodifen (Pascal and Scalla, 1999). In contrast, the tau class isoenzymes TaGST1-2, TaGST1-3, and TaGST1-4, which are active in detoxifying fenoxaprop ethyl, were enhanced in response to the safener fenchlorazole ethyl (Cummins et al, 1997).…”

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Induction of Glutathione S-Transferases in Arabidopsis by Herbicide Safeners

et al. 2002

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Herbicide safeners increase herbicide tolerance in cereals but not in dicotyledenous crops. The reason(s) for this difference in safening is unknown. However, safener-induced protection in cereals is associated with increased expression of herbicide detoxifying enzymes, including glutathione S-transferases (GSTs). Treatment of Arabidopsis seedlings growing in liquid medium with various safeners similarly resulted in enhanced GST activities toward a range of xenobiotics with benoxacor, fenclorim, and fluxofenim being the most effective. Safeners also increased the tripeptide glutathione content of Arabidopsis seedlings. However, treatment of Arabidopsis plants with safeners had no effect on the tolerance of seedlings to chloroacetanilide herbicides. Each safener produced a distinct profile of enhanced GST activity toward different substrates suggesting a differential induction of distinct isoenzymes. This was confirmed by analysis of affinity-purified GST subunits by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. AtGSTU19, a tau class GST, was identified as a dominant polypeptide in all samples. When AtGSTU19 was expressed in Escherichia coli, the recombinant enzyme was highly active toward 1-chloro-2,4-dinitrobenzene, as well as chloroacetanilide herbicides. Immunoblot analysis confirmed that AtGSTU19 was induced in response to several safeners. Differential induction of tau GSTs, as well as members of the phi and theta classes by safeners, was demonstrated by RNA-blot analysis. These results indicate that, although Arabidopsis may not be protected from herbicide injury by safeners, at least one component of their detoxification systems is responsive to these compounds.Plants actively detoxify both endogenous toxins, such as secondary metabolites and degradation products arising from oxidative stress, and exogenous man-made chemicals, such as herbicides, using a three-phase detoxification system (Neuefeind et al., 1997). In the first phase, oxidation, reduction, or hydrolysis reactions catalyzed by enzymes such as cytochrome P450 monooxygenases result in the exposure, or introduction, of a functional group. Phase two enzymes then catalyze the conjugation of these metabolites with sugars or the tripeptide glutathione (GSH). In the case of GSH, glutathione S-transferases (GSTs) catalyze this conjugation reaction. In the third phase of metabolism, molecules "tagged" with GSH are recognized by ATP-binding cassette transporters in the tonoplast or plasma membrane, which then transfer these conjugates into the vacuole or apoplast (Rea, 1999).GSTs constitute a family of multifunctional enzymes present in both plants and animals. These dimeric enzymes catalyze the conjugation of GSH to a variety of electrophilic, hydrophobic, and often toxic substrates, thereby reducing their toxicity (Marrs, 1996;Dixon et al., 1998). In addition to GSH conjugation, GSTs may also exhibit glutathione peroxidase (GPOX) or isomerase activities, or function as binding proteins known as ligandins (Edwards et al., ...

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Purification and characterization of a safener‐induced glutathione S‐transferase from wheat (Triticum aestivum)

Cited by 47 publications

References 55 publications

Organ-Specific Expression of Glutathione S-Transferases and the Efficacy of Herbicide Safeners in Arabidopsis

Organ-Specific Expression of Glutathione S-Transferases and the Efficacy of Herbicide Safeners in Arabidopsis

Effects of mercury on antioxidant mechanisms in the marine phanerogam Posidonia oceanica

Induction of Glutathione S-Transferases in Arabidopsis by Herbicide Safeners

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