Glyphosate - HH-RA.org

Bibliography Tag: glyphosate

Zobiole et al., 2010a

Luiz Henrique Saes Zobiole, Rubem Silvério de Oliveira Jr, Don Morgan Huber, Jamil Constantin, César de Castro, Fábio Alvares de Oliveira, Adilson de Oliveira Jr, “Glyphosate reduces shoot concentrations of mineral nutrients in glyphosate-resistant soybeans,” Plant and Soil, 2009, 328:1, DOI: 10.1007/s11104-009-0081-3.

ABSTRACT:

Although glyphosate-resistant (GR) technology is used in most countries producing soybeans (Glycine max L.), there are no particular fertilize recommendations for use of this technology, and not much has been reported on the influence of glyphosate on GR soybean nutrient status. An evaluation of different cultivar maturity groups on different soil types, revealed a significant decrease in macro and micronutrients in leaf tissues, and in photosynthetic parameters (chlorophyll, photosynthetic rate, transpiration and stomatal conductance) with glyphosate use (single or sequential application). Irrespective of glyphosate applications, concentrations of shoot macro- and micronutrients were found lower in the near-isogenic GR-cultivars compared to their respective non-GR parental lines Shoot and root dry biomass were reduced by glyphosate with all GR cultivars evaluated in both soils. The lower biomass in GR soybeans compared to their isogenic normal lines probably represents additive effects from the decreased photosynthetic parameters as well as lower availability of nutrients in tissues of the glyphosate treated plants. FULL TEXT

Gaines et al., 2010

Todd A. Gaines, Wenli Zhang, Dafu Wang, Bekir Bukun, Stephen T. Chisholm, Dale L. Shaner, Scott J. Nissen, William L. Patzoldt , Patrick J. Tranel , A. Stanley Culpepper , Timothy L. Grey , Theodore M. Webster , William K. Vencill, R. Douglas Sammons, Jiming Jiang, Christopher Prestoni, Jan E. Leacha, and Philip Westraa, “Gene amplification confers glyphosate resistance in Amaranthus palmeri,” PNAS, 2010, 107:3, DOI: 10.1073/PNAS/PNAS.0906649107.

ABSTRACT:

The herbicide glyphosate became widely used in the United States and other parts of the world after the commercialization of glyphosate-resistant crops. These crops have constitutive overexpression of a glyphosate-insensitive form of the herbicide target site gene, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). Increased use of glyphosate over multiple years imposes selective genetic pressure on weed populations. We investigated recently discovered glyphosate-resistant Amaranthus palmeri populations from Georgia, in comparison with normally sensitive populations. EPSPS enzyme activity from resistant and susceptible plants was equally inhibited by glyphosate, which led us to use quantitative PCR to measure relative copy numbers of the EPSPS gene. Genomes of resistant plants contained from 5-fold to more than 160-fold more copies of the EPSPS gene than did genomes of susceptible plants. Quantitative RT-PCR on cDNA revealed that EPSPS expression was positively correlated with genomic EPSPS relative copy number. Immunoblot analyses showed that increased EPSPS protein level also correlated with EPSPS genomic copy number. EPSPS gene amplification was heritable, correlated with resistance in pseudo-F₂ populations, and is proposed to be the molecular basis of glyphosate resistance. FISH revealed that EPSPS genes were present on every chromosome and, therefore, gene amplification was likely not caused by unequal chromosome crossing over. This occurrence of gene amplification as an herbicide resistance mechanism in a naturally occurring weed population is particularly significant because it could threaten the sustainable use of glyphosate-resistant crop technology. FULL TEXT

Eker et al., 2006

Selim Eker, Levent Ozturk, Atilla Yazici, Bulent Erenoglu, Volker Romheld, Ismail Cakmak, “Foliar-Applied Glyphosate Substantially Reduced Uptake and Transport of Iron and Manganese in Sunflower (Helianthus annuus L.) Plants,” Journal of Agricultural and Food Chemistry, 2006, DOI: 10.1021/JF0625196

ABSTRACT:

Evidence clearly shows that cationic micronutrients in spray solutions reduce the herbicidal effectiveness of glyphosate for weed control due to the formation of metal−glyphosate complexes. The formation of these glyphosate−metal complexes in plant tissue may also impair micronutrient nutrition of nontarget plants when exposed to glyphosate drift or glyphosate residues in soil. In the present study, the effects of simulated glyphosate drift on plant growth and uptake, translocation, and accumulation (tissue concentration) of iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) were investigated in sunflower (Helianthus annuus L.) plants grown in nutrient solution under controlled environmental conditions. Glyphosate was sprayed on plant shoots at different rates between 1.25 and 6.0% of the recommended dosage (i.e., 0.39 and 1.89 mM glyphosate isopropylamine salt). Glyphosate applications significantly decreased root and shoot dry matter production and chlorophyll concentrations of young leaves and shoot tips. The basal parts of the youngest leaves and shoot tips were severely chlorotic. These effects became apparent within 48 h after the glyphosate spray. Glyphosate also caused substantial decreases in leaf concentration of Fe and Mn while the concentration of Zn and Cu was less affected. In short-term uptake experiments with radiolabeled Fe (⁵⁹Fe), Mn (⁵⁴Mn), and Zn (⁶⁵Zn), root uptake of ⁵⁹Fe and ⁵⁴Mn was significantly reduced in 12 and 24 h after application of 6% of the recommended dosage of glyphosate, respectively. Glyphosate resulted in almost complete inhibition of root-to-shoot translocation of ⁵⁹Fe within 12 h and ⁵⁴Mn within 24 h after application. These results suggest that glyphosate residues or drift may result in severe impairments in Fe and Mn nutrition of nontarget plants, possibly due to the formation of poorly soluble glyphosate−metal complexes in plant tissues and/or rhizosphere interactions. FULL TEXT

Dill, 2005

Gerald M Dill, “Glyphosate-resistant crops: history, status and future,” Pest Management Science, 2005, 61, DOI: 10.1002/PS.1008.

ABSTRACT:

The commercial launch of glyphosate-resistant soybeans in 1996 signaled the beginning of a new era in weed management in row crops. Today, over 80% of the soybeans grown in the USA are glyphosate resistant. Since that time, many crops have been transformed that have allowed crop applications of many classes of herbicide chemistries. Crops currently under production include maize, soybean, cotton and canola. Transformation technology and selection methods have improved and the rate of development as well as the breadth of crops being considered as commercial targets has increased. On the basis of recent adoption rates by growers around the world, it appears that glyphosate-resistant crops will continue to grow in number and in hectares planted. However, global public acceptance of biotechnology-derived products will continue to impact the rate of adoption of this and other new innovations derived from transformation technology. FULL TEXT

Binimelis et al., 2009

Rosa Binimelis, Walter Pengue, Iliana Monterroso, ‘‘’Transgenic treadmill’: Responses to the emergence and spread of glyphosate-resistant johnsongrass in Argentina,” Geoforum, 2009, 40:4.

ABSTRACT:

The broad-spectrum herbicide glyphosate has become the largest-selling crop-protection product worldwide. The increased use of glyphosate is associated with the appearance of a growing number of tolerant or resistant weeds, with socio-environmental consequences apart from the loss of productivity. In 2002, a glyphosate-resistant biotype of johnsongrass (Sorghum halepense (L.)) appeared in Argentina and now covers at least 10,000 ha. This paper analyzes the driving forces behind the emergence and spread of this weed and also examines management responses and their implications.

Preventive strategies against glyphosate-resistant johnsongrass fail because of the institutional setting. Reactive measures, however, transfer the risks to the society and the environment through the introduction of novel genetically modified crops that allow the use of yet more herbicide. This in turn reinforces the emergence of herbicide-resistant weeds, constituting a new phenomenon of intensification, the “transgenic treadmill”. FULL TEXT

Mortensen et al., 2012

David A. Mortensen, J. Franklin Egan, Bruce D. Maxwell, Matthew R. Ryan, Richard G. Smith, “Navigating a Critical Juncture for Sustainable Weed Management,” BioScience, 2012, 62:1.

ABSTRACT:

Agricultural weed management has become entrenched in a single tactic—herbicide-resistant crops—and needs greater emphasis on integrated practices that are sustainable over the long term. In response to the outbreak of glyphosate-resistant weeds, the seed and agrichemical industries are developing crops that are genetically modified to have combined resistance to glyphosate and synthetic auxin herbicides. This technology will allow these herbicides to be used over vastly expanded areas and will likely create three interrelated challenges for sustainable weed management. First, crops with stacked herbicide resistance are likely to increase the severity of resistant weeds. Second, these crops will facilitate a significant increase in herbicide use, with potential negative consequences for environmental quality. Finally, the short-term fix provided by the new traits will encourage continued neglect of public research and extension in integrated weed management. Here, we discuss the risks to sustainable agriculture from the new resistant crops and present alternatives for research and policy. FULL TEXT

Thongprakaisang et al., 2013

Thongprakaisang S, Thiantanawat A, Rangkadilok N, Suriyo T, Satayavivad J, “Glyphosate induces human breast cancer cells growth via estrogen receptors,” Food and Chemical Toxicology, 2013 59, DOI: 10.1016/j.fct.2013.05.057.

ABSTRACT: Glyphosate is an active ingredient of the most widely used herbicide and it is believed to be less toxic than other pesticides. However, several recent studies showed its potential adverse health effects to humans as it may be an endocrine disruptor. This study focuses on the effects of pure glyphosate on estrogen receptors (ERs) mediated transcriptional activity and their expressions. Glyphosate exerted proliferative effects only in human hormone-dependent breast cancer, T47D cells, but not in hormone-independent breast cancer, MDA-MB231 cells, at 10⁻¹² to 10⁻⁶M in estrogen withdrawal condition. The proliferative concentrations of glyphosate that induced the activation of estrogen response element (ERE) transcription activity were 5-13 fold of control in T47D-KBluc cells and this activation was inhibited by an estrogen antagonist, ICI 182780, indicating that the estrogenic activity of glyphosate was mediated via ERs. Furthermore, glyphosate also altered both ERα and β expression. These results indicated that low and environmentally relevant concentrations of glyphosate possessed estrogenic activity. Glyphosate-based herbicides are widely used for soybean cultivation, and our results also found that there was an additive estrogenic effect between glyphosate and genistein, a phytoestrogen in soybeans. However, these additive effects of glyphosate contamination in soybeans need further animal study. FULL TEXT

Richard et al., 2005

Richard S, Moslemi S, Sipahutar H, Benachour N, Seralini GE, “Differential effects of glyphosate and roundup on human placental cells and aromatase, ” Environmental Health Perspectives, 2005, 113:6.

ABSTRACT:

Roundup is a glyphosate-based herbicide used worldwide, including on most genetically modified plants that have been designed to tolerate it. Its residues may thus enter the food chain, and glyphosate is found as a contaminant in rivers. Some agricultural workers using glyphosate have pregnancy problems, but its mechanism of action in mammals is questioned. Here we show that glyphosate is toxic to human placental JEG3 cells within 18 hr with concentrations lower than those found with agricultural use, and this effect increases with concentration and time or in the presence of Roundup adjuvants. Surprisingly, Roundup is always more toxic than its active ingredient. We tested the effects of glyphosate and Roundup at lower nontoxic concentrations on aromatase, the enzyme responsible for estrogen synthesis. The glyphosate-based herbicide disrupts aromatase activity and mRNA levels and interacts with the active site of the purified enzyme, but the effects of glyphosate are facilitated by the Roundup formulation in microsomes or in cell culture. We conclude that endocrine and toxic effects of Roundup, not just glyphosate, can be observed in mammals. We suggest that the presence of Roundup adjuvants enhances glyphosate bioavailability and/or bioaccumulation. FULL TEXT

Winchester et al., 2017

Winchester PD, Parvez S, Proctor C, Ying J, Gerona RR, “Fetal Exposure to Glyphosate,” Presentation, Pediatric Academic Societies, May 6-7, 2017, San Francisco, California.

SUMMARY:

Measured glyphosate in pregnant women to estimate fetal exposure and monitor potential adverse effects on pregnancy outcomes. Glyphosate was present in 91% of the urine samples and higher glyphosate levels were correlated with shorter pregnancies and lower birth weights. FULL TEXT

Niemann et al., 2015

Niemann L, Sieke C, Pfeil R, Solecki R., “A critical review of glyphosate findings in human urine samples and comparison with the exposure of operators and consumers,” 2015, Journal of Consumer Protection and Food Safety, 10: 3-12, DOI: 10.1007/s00003-014-0927-3.

ABSTRACT: For active substances in plant protection products (PPP) with well defined urinary elimination, no potential for accumulation and virtually no metabolism, measuring of urine levels could be a powerful tool for human biomonitoring. Such data may provide reliable estimates of actual internal human exposure that can be compared to appropriate reference values, such as the ‘acceptable daily intake (ADI)’ or the ‘acceptable operator exposure level (AOEL)’. Traces of the active compound glyphosate were found in human urine samples, probably resulting either from occupational use for plant protection purposes or from dietary intake of residues. A critical review and comparison of data obtained in a total of seven studies from Europe and the US was performed. The conclusion can be drawn that no health concern was revealed because the resulting exposure estimates were by magnitudes lower than the ADI or the AOEL. The expected internal exposure was clearly below the worst-case predictions made in the evaluation of glyphosate as performed for the renewal of its approval within the European Union. However, differences in the extent of exposure with regard to the predominant occupational and dietary exposure routes and between Europe and North America became apparent. FULL TEXT

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