Enzymatic Hydrolysis of Herbicides in Plants

Hoagland, Robert E.; Graf, George

doi:10.1017/s0043174500035700

Cited by 14 publications

(1 citation statement)

References 16 publications

(16 reference statements)

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“…For example, the remarkable selectivity of propanil to rice is due to the activity of an aryl acylamidase (AAI) that hydrolyses the herbicide to 3,4-dichloroaniline (DCA) and propionic acid in rice plants (Frear & Still, 1968;Still & Kuzirian, 1967;Yih, McRae & Wilson, 1968). Selectivity of propanil to rice is achieved because most weeds have no AAI or, if present, the enzyme has a much lower activity compared to that of rice (Hoagland & Graf, 1972). However, AAI is found in weedy rice and in several wild species of the genus Oryza whose response to propanil is related to the activity of the enzyme (Chen & Matsunaka, 1990).…”

Section: Available Alternatives To Herbicide Resistant Ricementioning

confidence: 99%

Herbicide resistant rice (Oryza sativa L.): Global implications for weedy rice and weed management*

Olofsdotter

Valverde²,

Madsen³

2000

Annals of Applied Biology

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Summary Rice cultivars resistant to broad‐spectrum herbicides have been developed and their commercial release is imminent, especially for imidazolinone and glufosinate resistant varieties in the USA and Latin America. Glyphosate‐resistant rice should follow within a few years. Rice growers throughout the world could benefit from the introduction of herbicide‐resistant rice cultivars that would allow in‐crop, selective control of weedy Oryza species. Other perceived benefits are the possibility to control ‘hard‐to‐kill’ weed species and weed populations that have already evolved resistance to herbicides currently used in rice production, especially those of the Echinochloa species complex. Weed management could also be improved by more efficient post‐emergence control. Introduction of herbicide resistant rice could also bring areas heavily infested with weedy rice that have been abandoned back to rice production, allow longer term crop rotations, reduce consumption of fossil fuels, promote the replacement of traditional chemicals by more environmentally benign products, and provide more rice grain without adding new land to production. There are also concerns, however, about the impact of releasing herbicide‐resistant rice on weed problems. Of most concern is the possibility of rapid transfer of the resistance trait to compatible weedy Oryza species. Development of such herbicide resistant weedy rice populations would substantially limit the chemical weed management options for farmers. Herbicide‐resistant rice volunteers also could become problematic, and added selection pressure to weed populations could aggravate already serious weed resistance problems. Because of the risk of weedy Oryza species becoming resistant to broad‐spectrum herbicides, mitigating measures to prevent gene flow, eventually attainable by both conventional breeding and molecular genetics, have been proposed. With commercialisation of the first herbicide resistant varieties planned for 2001, these mitigating measures will not be available for use with this first generation of herbicide resistant rice products. Release of herbicide resistant rice should depend on a thorough risk assessment especially in areas infested with con‐specific weedy rice or intercrossing weedy Oryza species. Regulators will have to balance risks and benefits based on local needs and conditions before allowing commercialisation of herbicide‐resistant rice varieties. If accepted, these varieties should be considered as components of integrated weed management, and a rational herbicide use and weedy rice control should be promoted to prevent losing this novel tool.

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Section: Available Alternatives To Herbicide Resistant Ricementioning

confidence: 99%

Herbicide resistant rice (Oryza sativa L.): Global implications for weedy rice and weed management*

Olofsdotter

Valverde²,

Madsen³

2000

Annals of Applied Biology

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Resistance Mechanism of Propanil-Resistant Barnyardgrass: II. In-vivo Metabolism of the Propanil Molecule

1997

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Propanil-resistant barnyardgrass populations, previously veriÐed in Arkansas rice Ðelds and in greenhouse tests, were examined in the laboratory to ascertain if the resistance mechanism in this weed biotype was herbicide metabolism. Propanil-resistant barnyardgrass was controlled [95% in the greenhouse when carbaryl (an aryl acylamidase inhibitor) was applied two days prior to propanil. Laboratory studies with 14C-radiolabelled propanil indicated that the herbicide was hydrolysed in propanil-resistant barnyardgrass and rice to form 3,4-dichloroaniline, but no detectable hydrolysis occurred in susceptible barnyardgrass. Two additional polar metabolites were detected in propanil-resistant barnyardgrass and rice and tentatively identiÐed by thin layer chromatography. Overall, metabolites in the resistant barnyardgrass had values similar to those R f in rice, indicating similar metabolism for both species. These data, coupled with data from a previous report on the resistant biotype showing no di †erential absorption/translocation or molecular modiÐcation of the herbicide binding site in the resistant biotype, indicate that the resistance mechanism is metabolic degradation of propanil.

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The relationship of metabolism studies to the modes of action of herbicides

Kirkwood¹

1983

Pestic. Sci.

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Metabolism studies are necessary in the understanding of the mode of action of herbicides, their loss of activity and their selectivity. Molecular change of a herbicide may involve photochemical degradation, and non‐enzymic or enzymic reactions that normally inactivate, but in some cases activate, a compound. Molecular change resulting in activation is discussed with regard to the (2,4‐dichlorophenoxy)‐alkanoic acids, the pyridines paraquat and diquat, the anilides benzoylprop‐ethyl and flamprop‐methyl, and the thiocarbamates. Inactivation due to metabolism is reviewed with regard to herbicides applied to soil and foliage. Of the soil‐applied herbicides, the 1,3,5‐triazines and the nitrile dichlobenil are exemplified as cases in which selectivity may be due largely to interspecific differences in metabolism. Of the foliage‐applied translocated compounds, the metabolism of the phenoxyalkanoic acid herbicides has been extensively investigated and may involve conjugation, side‐chain degradation or extension, ring hydroxylation and protein binding. The mode of action of glyphosate, asulam, dalapon and aminotriazole in perennial weeds is discussed with particular reference to their metabolism.

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Enzymatic Hydrolysis of Herbicides in Plants

Cited by 14 publications

References 16 publications

Herbicide resistant rice (Oryza sativa L.): Global implications for weedy rice and weed management*

Herbicide resistant rice (Oryza sativa L.): Global implications for weedy rice and weed management*

Resistance Mechanism of Propanil-Resistant Barnyardgrass: II. In-vivo Metabolism of the Propanil Molecule

The relationship of metabolism studies to the modes of action of herbicides

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