How prevalent is chemical hormesis in the natural and experimental worlds?

Mushak, Paul

doi:10.1016/j.scitotenv.2012.11.028

Cited by 24 publications

(12 citation statements)

References 33 publications

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“…Simultaneous estimates of the fre quency of nonhormetic dose-response relationships required for reliable determination of hormesis frequency were not done in these analyses. No evidence in the available literature was found to show that hormesis was generalizable in the natural or experi mental worlds (27). Chemical hormesis has been mainly evaluated for isolated endpoints (22).…”

Section: Discussionmentioning

confidence: 99%

Stimulatory Effects of Sublethal Doses of Dimethachlon on Sclerotinia sclerotiorum

Zhou

Liang

et al. 2014

Plant Disease

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A b s t r a c t -X. 2014. Stimulatory effects of sublethal doses of dimethachlon on Sclerotinia sclerotiorum. Plant Dis. 98:1364-1370.Growth and virulence stimulations of sublethal doses of fungicides on plant-pathogenic fungi and oomycetes have been reported and the stimulatory effects are potentially relevant to plant disease manage ment. Sclerotinia sclerotiorum is one of the most devastating and eco nomically important necrotrophic fungal phytopathogens, capable of infecting more than 400 species of plants worldwide. In order to study stimulatory effects of sublethal doses of fungicides on S. sclerotiorum, 55 dimethachlon-sensitive isolates and 3 dimethachlon-resistant iso lates of S. sclerotiorum were assayed to determine effects of sublethal doses of dimethachlon on mycelial growth rate on potato dextrose agar (PDA) media and virulence on oilseed rape plants. Results showed that all 3 dimethachlon-resistant isolates and 13 of the 55 sensitive isolates exhibited stimulatory responses to sublethal doses of dimethachlon.Dimethachlon-resistant isolates grew significantly (P < 0.05) faster on PDA media amended with dimethachlon at 0.5 to 4 pg/ml than on fungicide-free PDA media. As for virulence on detached leaves of oilseed rape plants, lesion diameters of dimethachlon-resistant isolates after growth on PDA media amended with dimethachlon at 0.5 to 2 pg/ml were significantly larger (P < 0.05) than the control. The maxi mum stimulatory effects were 42.40 to 59.80%. In pot experiments, for both dimethachlon-sensitive and -resistant isolates, significant (P < 0.05) virulence stimulations were observed after spraying with di methachlon at a concentration of 2 pg/ml. After growing on dimethachlon-amended PDA media, H20 2 sensitivity of S. sclerotiorum de creased significantly (P < 0.05) compared with the nonamended PDA control.At present, fungicides still play an essential and, in most cases, maybe the most important role in successful and effective plant disease management. When controlling fungal and oomycete plant pathogens by application of fungicides, a small amount of phyto pathogens will inevitably be exposed to sublethal doses of fungi cides. Exposure to sublethal doses of fungicides can occur under diverse circumstances, such as inappropriate fungicide applica tions, in combination with other fungicides with different active ingredient, and emergence of fungicide-resistant strains (16,26). Normal doses of fungicides for sensitive phytopathogen strains are perhaps sublethal doses for fungicide-resistant strains. In most experiments, researchers are mainly interested in effects of normal (high) doses of fungicides on plant pathogens, and effects of suble thal doses of fungicides have been largely ignored.In experiments to test in vitro sensitivity of Sclerotinia scleroti orum (Lib.) de Bary to fungicide, we noticed that some isolates grew faster on potato dextrose agar (PDA) media amended with sublethal doses of fungicides than on fungicide-free PDA media. There have been some reports of plant pathogen growth...

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Section: Discussionmentioning

confidence: 99%

Stimulatory Effects of Sublethal Doses of Dimethachlon on Sclerotinia sclerotiorum

Zhou

Liang

et al. 2014

Plant Disease

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“…Therefore, knowledge on the specificity and number of endpoints stimulated by a specific compound is limited. Nevertheless, hormesis is usually observed for a single endpoint at a single time point and does not require or imply a stimulatory response at other times after treatment or for any other endpoint at any time . For example, some herbicides (e.g.…”

Section: Factors Influencing Herbicide Hormesismentioning

confidence: 99%

“…Nevertheless, hormesis is usually observed for a single endpoint at a single time point and does not require or imply a stimulatory response at other times after treatment or for any other endpoint at any time. 5,38,39 For example, some herbicides (e.g. bromacil, bromoxynil, chloramben, propachlor, terbacil, EPTA and MSMA) can stimulate root growth at low doses but have no hormetic effect on shoot growth, while the opposite was observed for glyphosate in maize and soybean.…”

Section: Endpoint Measuredmentioning

confidence: 99%

Herbicides and plant hormesis

Belz

Duke

2014

Pest Management Science

166

173

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Herbicide hormesis is commonly observed at subtoxic doses of herbicides and other phytotoxins. The occurrence and magnitude of this phenomenon are influenced by plant growth stage and physiological status, environmental factors, the endpoint measured and the timing between treatment and endpoint measurement. The mechanism in some cases of herbicide hormesis appears to be related to the target site of the herbicide, whereas in other examples hormesis may be by overcompensation to moderate stress induced by the herbicides or a response to disturbed homeostasis. Theoretically, herbicide hormesis could be used in crop production, but this has been practical only in the case of the use of herbicides as sugar cane 'ripeners' to enhance sucrose accumulation. The many factors that can influence the occurrence, the magnitude and the dose range of hormetic increases in yield for most crops make it too unpredictable and risky as a production practice with the currently available knowledge. Herbicide hormesis can cause undesired effects in situations in which weeds are unintentionally exposed to hormetic doses (e.g. in adjacent fields, when shielded by crop vegetation). Some weeds that have evolved herbicide resistance may have hormetic responses to recommended herbicide application rates. Little is known about such effects under field conditions. A more complete understanding of herbicide hormesis is needed to exploit its potential benefits and to minimize its potential harmful effects in crop production.

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“…However, generalizations, according to which ''hormetic-like biphasic dose responses may represent a general biological dose-response pattern or strategy'' 11 are not sufficiently supported by scientific evidence. 15,16 Moreover, hormesis merely further defines one response; but most toxicoses have many responses. 10 Some noxious agents can have a cumulative effect or act synergistically with other harmful factors, for example, on the cells with a limited or no potential for cellular regeneration such as cardiomyocytes or neurons.…”

mentioning

confidence: 99%

Hormesis

Jargin

2015

Hum Exp Toxicol

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How prevalent is chemical hormesis in the natural and experimental worlds?

Cited by 24 publications

References 33 publications

Stimulatory Effects of Sublethal Doses of Dimethachlon on Sclerotinia sclerotiorum

Stimulatory Effects of Sublethal Doses of Dimethachlon on Sclerotinia sclerotiorum

Herbicides and plant hormesis

Hormesis

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