, 2012). In a review on this topic, however, conflicting results were found, with most studies indicating that mineral nutrition is not affected by glyphosate tolerance trait or application of glyphosate (Duke et al.,
2012). Glyphosate has been shown to reduce photosynthesis and nutrient uptake in GM-soy, in greenhouse and field trials, both for first and second generation of glyphosate resistant soy plants. High glyphosate application rates have been shown to reduce alfa-linolenic acid (ALA, 18:3n−3) but increase oleic acid (OL, 18:1n−9) ( Bellaloui, Zablotowicz, Reddy, & Abel, 2008), i.e., producing a less healthy profile of fatty acids. Glyphosate may also, depending on soil type, alter micronutrient status, in PLX3397 order particular Mn and Zn. Our data showed significantly Pembrolizumab higher Zn concentrations in organic soy samples (mean 37.0 mg/kg), but no differences between GM and conventional soy samples (mean 30.4 and 31.7 mg/kg, respectively). This indicates that factors other than glyphosate may be relevant, such as the use of
organic versus synthetic fertiliser or long-term accumulated differences in soil treatment and quality. Status of the micronutrient Mn was not affected by the production system in our samples. In general, a healthy microbial community, ‘the plant microbiome’, in the soil of the rhizosphere is an important contributing factor for plant trait characteristics and plant health (Lundberg et al., 2012). Glyphosate has the potential to adversely affect microbial communities present in soils into which plants are rooted, i.e. increased colonisation by Fusarium ( Kremer & Means, 2009). AMPA is mildly phytotoxic, and leads to
reduced photosynthesis (‘yellowing’) and transpiration rates in soy plants (Ding, Reddy, Zablotowicz, Bellaloui, & Bruns, 2011). Other ingredients of glyphosate-based herbicides have also been described as detrimental to GM-soy. We found a significant positive correlation between AMPA residue levels in the GM soybeans and increasing levels of LA and iron (Fe). The acceptance level of glyphosate in food and feed, i.e., the maximum residue level (MRL) GNAT2 has been increased by authorities in countries where Roundup-Ready GM crops are produced or where such commodities are imported. In Brazil, the MRL in soybean in 2004 was increased from 0.2 to 10 mg/kg: a 50-fold increase, but only for GM-soy. The MRL for glyphosate in soybeans has also increased in the US and Europe. In Europe, it was raised from 0.1 to 20 mg/kg in 1999, and the same MRL of 20 mg/kg was adopted by the US based on recommendations of the Codex Alimentarius Commission. In all of these cases, MRL values appear to have been adjusted, not based on new evidence indicating glyphosate toxicity was less than previously understood, but pragmatically in response to actual observed increases in the content of residues in glyphosate-tolerant GM soybeans.