The Activity of Oxyradical-Detoxifying Enzymes Is Not Correlated with Paraquat Resistance inConyza canadensis(L.) Cronq.

Turcsányi, Enikö; Darkó, Éva; Borbély, György; Lehoczki, E.

doi:10.1006/pest.1998.2326

Cited by 21 publications

(13 citation statements)

References 47 publications

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“…The opinion prevails that the antioxidant enzyme cycle only provides a tem porary protection, until some other type of mechanism(s) ensuring long-term survival starts to operate. Experim ents carried out on plants belonging to five different R biotypes of C onyza canadensis L. growing at various sites in Hungary proved convincingly that despite the very different resistance factors there was neither a dif ference in SOD activity (Turcsänyi et al, 1994) nor in ascorbate peroxidase, glutathione reductase and catalase before or after spraying with paraquat (Turcsänyi et al, 1998).…”

Section: Hypotheses On the Mechanism Of Paraquat Resistancementioning

confidence: 99%

“…In paraquat-atrazine coresistant (PqA R ) plants, RF val ues varied between 210 and 650, depending on the prehistory of the plant (Szigeti et al, , 1994. In the flowering stage RF values as high as 1000 were reported (Turcsänyi et al, 1998). When treated with diquat, the R F value of the PqR bio type, resistant only to paraquat, was 47, while that of the PqA R biotypes found at various sites in Hungary exhibited resistance factors of between 50 and 110 (Szigeti et al, 1994).…”

Section: Characteristics Of Paraquat-resistant Biotypes Of Conyza Canmentioning

confidence: 99%

“…The possibility of an increase in SOD activity as part of the resistance mechanism was excluded by the simultaneous application of the Cu-chelator N,N-diethyldithiocarbamate (DDC) and paraquat (D arkö et al, 1994;Turcsänyi et al, 1998). DDC is the in vivo inhibitor of Cu/ZnSOD (Heikkila et al, 1976).…”

Section: Effect Of Paraquat Treatment On the Chloroplast Structure Pmentioning

confidence: 99%

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Paraquat Resistance of Weeds - the Case of Conyza canadensis (L.) Cronq

Szigeti

Rácz

Lásztity

2001

Zeitschrift Für Naturforschung C

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C on yza, Herbicide Resistance, ParaquatThe paper gives an overview of literature on paraquat resistance of weeds and the pro posed mechanism of resistance. New results we achieved on horseweed ( C onyza canadensis /L J, Cronq.) are discussed in detail.It was demonstrated that there is no significant constitutive difference related to the para quat resistance between untreated susceptible and paraquat-resistant horseweed plants. The lower sensitivity of flowering resistant plants may be due to the fact that paraquat content in treated leaves of flowering resistant plants was only 25% as compared to those measured at rosette stage. Our results confirm that paraquat resistance is not based on elevated level and activity of antioxidant enzyme system. The hypothesized role of polyam ines in the resis tance mechanisms can be excluded. The higher putrescine and total polyamine content of paraquat treated resistant leaves can rather be regarded as a general stress response, than as a symptom of paraquat resistance. A paraquat-inducible protein is supposed to play a role in the resistance, which presumably functions by binding paraquat to an inactivating site and/ or by carrying paraquat to metabolically inactive cell compartment (vacuole, cell wall). From m odel experiments it is concluded that paraquat and diquat preferentially form hydrophylic interactions with proteins containing a higher amount o f lysine and glutamic acid. C onse quently, the reason for paraquat resistance in horseweed is probably a hydrophylic interac tion of paraquat with a protein, leading to inactivation of paraquat through forming a conju gate and/or sequestration into the vacuole or the cell wall. Bipyridyls and their mode of actionThe two best-known bipyridyl compounds, para quat (l,r-dim ethyl-4,4'-bipyridinium ) and diquat (9,10-dihydro-8a,10a-diazoniaphenanthrene), are used, generally in the form of haloid salts, as the active ingredients of post-emergent, non-selective, contact herbicides. These compounds are applied in vineyards, orchards and forests for total weed control, in horticulture for the weed control of seedbeds, and in the field for defoliation and desic cation of crops. These compounds are inactivated in the soil, as they bind irreversibly to clay miner als, so they have no residual effects. The com pounds are extremely toxic to vertebrates, and thus to man: the L D 50 value characterising the oral A bbreviations: LHCP, light harvesting chlorophyll pro tein complex; PqAR , paraquat/atrazine coresistant; PqR, paraquat-resistant; PS I, II, photosystem I, II; R, resistant; RF, resistance factor; S, susceptible; SOD, su peroxide dismutase. toxicity in rats is 157 mg/kg body weight for para quat. The minimum lethal dose by oral ingestion in human beings is about 35 mg/kg body weight. Because of the high toxicity the use of herbicides containing paraquat is severely restricted or banned in many E uropean countries. N everthe less, investigations on its effect and resistance mechanisms continue with scarcely diminished in tensity....

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Section: Hypotheses On the Mechanism Of Paraquat Resistancementioning

confidence: 99%

Section: Characteristics Of Paraquat-resistant Biotypes Of Conyza Canmentioning

confidence: 99%

Section: Effect Of Paraquat Treatment On the Chloroplast Structure Pmentioning

confidence: 99%

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Paraquat Resistance of Weeds - the Case of Conyza canadensis (L.) Cronq

Szigeti

Rácz

Lásztity

2001

Zeitschrift Für Naturforschung C

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“…In horseweed no elevated levels of enzymes detoxifying reactive oxygen radicals could be detected after Pq treatment (Turcsányi et al, 1998). Ferritin2 may therefore play an important role in oxygen radical detoxification by decreasing the cellular level of uncomplexed iron and reducing the production of hydroxyl radicals.…”

Section: Article In Pressmentioning

confidence: 98%

“…In these plants Pq is able to reach the chloroplasts, as indicated by the transitory inhibition of their functional activity characterized by ratio of variable and maximum fluorescence (F v / F m ) (Lehoczki et al, 1992). These plants have low activities of enzymes that detoxify oxygen radicals (Turcsányi et al, 1998). It has been suggested that Pq-inducible protein(s) may play a role in resistance.…”

Section: Introductionmentioning

confidence: 99%

Ferritin2 gene in paraquat-susceptible and resistant biotypes of horseweed Conyza canadensis (L.) Cronq.

Soós

Jóri

Páldi

et al. 2006

Journal of Plant Physiology

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Mechanisms of resistance to paraquat in plants

Hawkes

2014

Pest Management Science

108

109

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The aim of this brief review is to draw information from studies of the mechanism of evolved resistance in weeds, together with information from laboratory studies of paraquat tolerance in model plants. Plants having mutations that limit paraquat uptake into cytoplasm, that confer various stress tolerances or that have transgenes that co-express two or more of the chloroplast Halliwell-Asada cycle enzymes can all exhibit enhanced tolerance to paraquat. However, none of these mechanisms correspond to the high-level resistances that have evolved naturally in weeds. Most, but not all, of the evidence from studies of paraquat-resistant biotypes of weeds can reasonably be reconciled with the proposal of a single major gene mechanism that sequesters paraquat away from chloroplasts and into the vacuole. However, the molecular details of this putative mechanism remain ill-defined.

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The Activity of Oxyradical-Detoxifying Enzymes Is Not Correlated with Paraquat Resistance inConyza canadensis(L.) Cronq.

Cited by 21 publications

References 47 publications

Paraquat Resistance of Weeds - the Case of Conyza canadensis (L.) Cronq

Paraquat Resistance of Weeds - the Case of Conyza canadensis (L.) Cronq

Ferritin2 gene in paraquat-susceptible and resistant biotypes of horseweed Conyza canadensis (L.) Cronq.

Mechanisms of resistance to paraquat in plants

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