Glyphosate effect

Figure 13. Glyphosate effect on anthraquinone production and shikimate accumulation in G. mollugo cell cultures ( 84j. Cells were harvested 10 days after inoculation with 2 cm of packed cells into 25 mL medium containing glyphosate. Anthraquinone content of the cells was corrected for the amount present in the inoculum.

Herbicide Glasses and Databases. Herbicides can be classified as selective and nonselective. Selective herbicides, like 2,4-D (2,4-dichlorophenoxyacetic acid), metolachlor [51218-45-2] and EPTC [759-94 ] are more effective against some types of plants than others, eg, broadleaved plants vs grasses. Glyphosate [1071 -83-6] is representative of the nonselective herbicides used for total vegetable control. 

Uses. The largest usage of PCl is to produce phosphonic acid, H PO, which in reaction with iminodiacetic acid and formaldehyde forms a glyphosate intermediate that is decarboxymethylated to glyphosate, an effective nonselective herbicide (see Herbicides). Phosphoms trichloride is also a convenient chlorinating reagent for producing various acyl and alkyl chlorides. 

Figure 3, Effect of pH on initial rate of nitrosation of glyphosate at 25 C ( 2), Initial concentrations of glyphosate and sodium nitrite, 10,5 and 7.5mM respectively.

Glyphosate also inhibits the activity of a form of 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase (13), however, this inhibition is relatively weak. Effects of glyphosate on the enzymes of aromatic amino acid synthesis have been described in more detail in recent reviews (14-17). 

The effects of glyphosate on phenolic compound production are two-fold 1) accumulation of phenolic compounds that are derivatives of aromatic amino acids is reduced and 2) pools of phenolic compounds derived from constituents of the shikimate pathway prior to 5-enolpyruvylshikimate-3-phosphate become larger. Assays that do not distinguish between effects on these two groups, such as that for hydroxyphenolics of Singleton and Rossi (18), can lead to equivocal and difficult to interpret results (e.g. 3-5). 

Figure 3. Effect of glyphosate on fresh weight (o), chlorophyll content (x), and anthocyanin content ( ) of excised buckwheat cotyledons after 24 h of treatment in the light. Reproduced with permission from Ref. 6. Copyright 1980, Plant Physiology.

Many herbicides and other chemicals have been reported to influence levels of various phenolic compounds in higher plants by unknown mechanisms. It is unlikely that more than a few of these compounds have a primary influence on secondary phenolic compound synthesis. For instance, in our survey of the effects of 17 herbicides on anthocyanin accumulation, only glyphosate appeared to directly influence accumulation (31). The effects of several compounds on secondary phenolic compound production for which the mechanism of influence is unknown are summarized in Table II. A much longer list could be derived from the literature. Unfortunately, many of these compounds are phytotoxic or are known to have effects other than on secondary aromatic compound production. In most cases the effects on these compounds correlate well with extractable PAL activity (31, 71, 72, 73, 74) (Figure 5), even though they do not directly affect the enzyme. 

Little information has been published on pesticide degradation products, produced in coffee, that may have significant physiological effects. Some information has been published, however, for glyphosate,191 aldicarb,194 and carbofuran,187 although there is some controversy surrounding the carbofuran data.188... 

Chan, K. and S.C. Leung. 1986. Effects of paraquat and glyphosate on growth, respiration, and enzyme activity of aquatic bacteria. Bull. Environ. Contam. Toxicol. 36 52-59. 

Gimsing, A.L. Borggaard, O.K. (2001) Effect of KCl and CaCl2 as background electrolytes on the competitive adsorption of glyphosate and phosphate on goethite. Clays Clay Min. 49 270-275... 

Genetic effects in human populations, guidelines for the study of (No. 46,1985) Glyphosate (No. 159,1994)... 

Kleter, G.A., Harris, C.A., Stephenson, G.R. and Unsworth, J. (2008) Comparison of herbicide regimes and the associated potential environmental effects of glyphosate-resistant crops vs. what they replace in Europe. Pestic Manage Sci, 64, 479-488. 

Glyphosate Urinary glyphosate Exposure pathways risk assessment external dose to toxic effect in animals limited analysis of biomarker to external dose Biomarker results can be put into risk context by using existing risk assessment... 

With the culture of soybean and field com so intimately intertwined throughout the Midwest, changes in soybean weed control affect com weed control as well. One real effect of the widespread adoption of glyphosate-tolerant varieties has been the disincentive to discover and develop new products and new chemistries. Since the advent of glyphosate-resistant soybean, very few products have been developed for that market. 

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