Transgenic Tobacco Plants Expressing a Bacterial Detoxifying Enzyme are Resistant to 2,4-D

Streber, W.; Willmitzer, Lothar

doi:10.1038/nbt0889-811

Cited by 76 publications

(35 citation statements)

References 26 publications

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“…Other bacterial enzymes have been transformed into plants to increase their herbicide detoxification capabilities, although none have used P450s. These include a phosphonothricin acetyltranferase (DeBlock et al, 1987), bromoxynil nitrilase (Stalker et al, 1988), and a 2,4-D-dealkylating enzyme that is "monooxygenase-like," but not a P450 (Streber and Willmitzer, 1989).…”

Section: Discussionmentioning

confidence: 99%

Plant Expression of a Bacterial Cytochrome P450 That Catalyzes Activation of a Sulfonylurea Pro-Herbicide

et al. 1994

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The Sfreptomyces griseolus gene encoding herbicide-metabolizing cytochrome P450sul (CYP105Al) was expressed in transgenic tobacco (Nicofiana tabacum). Because this P450 can be reduced by plant chloroplast ferredoxin in vitro, chloroplast-targeted and nontargeted expression were compared. Whereas P450sul antigen was found in the transgenic plants regardless of the targeting, only those with chloroplast-directed enzyme performed P450sul-mediated N-dealkylation of the sulfonylurea 2-methylethyl-2,3-dihydro-N-[(4,6-dimethoxypyrimidin-2-yl)aminocarbonyl~-1,2-benzoisothiazole-7-sulfonamide-1,l-dioxide (R7402). Chloroplast targeting appears to be essential for the bacterial P450 to function in the plant. Because the R7402 metabolite has greater phytotoxicity than R7402 itself, plants bearing active P450sul are susceptible to injury from R7402 treatment that is harmless to plants without P45OSul. Thus, P450sul expression and R7402 treatment can be used as a negative selection system in plants. Furthermore, expression of P450sul from a tissue-specific promoter can sequester production of the phytotoxic R7402 metabolite to a single plant tissue. In tobacco expressing P450sul from a tapetum-specific promoter, treatment of immature flower buds with R7402 caused dramatically lowered pollen viability. Such treatment could be the basis for a chemical hybridizing agent.P450 monooxygenases play a central role in plant response to a variety of environmental challenges, including herbicide and other pesticide treatments (Cole, 1983;Durst, 1991). The best examples of this role are those P450s that can chemically alter an herbicide to a form with reduced phytotoxicity, resulting in much higher herbicide tolerance in the plant where this metabolism occurs (Frear et al., 1969(Frear et al., ,1991Sweetser et al., 1982; Jacobson and Shimabukuru, 1984;Brown, 1990). Significant variability in P450 enzyme activity exists among plant species, both in the presence of distinct enzymic forms and in their range of substrate specificity. This variability is a major determinant in herbicide selectivity, the differential herbicide sensitivity of weed and crop species. Altering herbicide selectivity, particularly confemng resistance in a crop plant, might be accomplished by expression of Present address:

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Section: Discussionmentioning

confidence: 99%

Plant Expression of a Bacterial Cytochrome P450 That Catalyzes Activation of a Sulfonylurea Pro-Herbicide

et al. 1994

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“…2,4-Dichlorophenoxyacetic acid (2,4-D) mono-oxygenase encoded by the tfdA gene catalyzes the ®rst step in the bacterial 2,4-D degradative pathway (Fig 4). 8 When the gene was expressed in plants under the control of either a constitutive or a light-inducible promoter, the transgenic plants tolerated elevated levels of foliar-applied 2,4-D. 31,32 The bxn gene encoded a speci®c nitrilase that converts bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) to its primary metabolite 3,5-dibromo-4-hydroxybenzoic acid (Fig 5). The transgenic plants expressing the enzyme tolerated high levels of a commercial formulation of bromoxynil.…”

Section: Transfer Of Herbicide Resistance Genes Into Cropsmentioning

confidence: 99%

The use of cytochrome P450 genes to introduce herbicide tolerance in crops: a review

1999

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Mechanisms of herbicide resistance include (1) modi®ed target site, (2) enhanced detoxi®cation or delayed activation, and (3) alterations in the uptake, translocation, or compartmentalization of a herbicide. The ®rst two mechanisms have mainly been identi®ed in plants. Herbicide resistance genes were isolated for several herbicides of different modes of action. Genes that coded for herbicide target or detoxi®cation enzymes were transferred into crop plants. The transgenic plants expressing these genes were tolerant of the active ingredients of herbicides.Before commercialization, the transgenic plants were tested in the ®eld for risk assessment. In the case of crops with herbicide detoxi®cation enzymes, including cytochrome-P450-species-metabolizing xenobiotics, the substrate speci®city of the enzymes as well as the toxicological properties of the herbicide metabolites and the pattern of secondary metabolites in plants must be evaluated.

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“…These include for example, bromoxynil resistance crops bearing a nitrilase (Freyssinet et al, 1996), glufosinateresistant crops bearing an acetyl-transferase (Vasil, 1996), 2, 4-D resisting crops bearing a highly specific soluble cytochrome P-450 monooxygenase (Streber & Willmitzer, 1989), phenmidipham resisting crops bearing a bacterial gene and dalapon resisting crops bearing a dehalogenase (Buchanon-Wallaston et al, 1992). Of these, only the bromoxynil-and glufosinate resistant crops have reached commercialization.…”

Section: Metabolically Resistant Genetically Modified -Herbicide Resimentioning

confidence: 99%

Herbicide Tolerant Food Legume Crops: Possibilities and Prospects

Singh¹,

Yadav²

2012

Herbicides - Properties, Synthesis and Control of Weeds

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Transgenic Tobacco Plants Expressing a Bacterial Detoxifying Enzyme are Resistant to 2,4-D

Cited by 76 publications

References 26 publications

Plant Expression of a Bacterial Cytochrome P450 That Catalyzes Activation of a Sulfonylurea Pro-Herbicide

Plant Expression of a Bacterial Cytochrome P450 That Catalyzes Activation of a Sulfonylurea Pro-Herbicide

The use of cytochrome P450 genes to introduce herbicide tolerance in crops: a review

Herbicide Tolerant Food Legume Crops: Possibilities and Prospects

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