Review of potential environmental impacts of transgenic glyphosate-resistant soybean in Brazil

Abstract

Transgenic glyphosate-resistant soybeans (GRS) have been commercialized and grown extensively in the Western Hemisphere, including Brazil. Worldwide, several studies have shown that previous and potential effects of glyphosate on contamination of soil, water, and air are minimal, compared to those caused by the herbicides that they replace when GRS are adopted. In the USA and Argentina, the advent of glyphosate-resistant soybeans resulted in a significant shift to reduced- and no-tillage practices, thereby significantly reducing environmental degradation by agriculture. Similar shifts in tillage practiced with GRS might be expected in Brazil. Transgenes encoding glyphosate resistance in soybeans are highly unlikely to be a risk to wild plant species in Brazil. Soybean is almost completely self-pollinated and is a non-native species in Brazil, without wild relatives, making introgression of transgenes from GRS virtually impossible. Probably the highest agricultural risk in adopting GRS in Brazil is related to weed resistance. Weed species in GRS fields have shifted in Brazil to those that can more successfully withstand glyphosate or to those that avoid the time of its application. These include Chamaesyce hirta (erva-de-Santa-Luzia), Commelina benghalensis (trapoeraba), Spermacoce latifolia (erva-quente), Richardia brasiliensis (poaia-branca), and Ipomoea spp. (corda-de-viola). Four weed species, Conyza bonariensis, Conyza Canadensis (buva), Lolium multiflorum (azevem), and Euphorbia heterophylla (amendoim bravo), have evolved resistance to glyphosate in GRS in Brazil and have great potential to become problems.

Glyphosate’s Suppression of Cytochrome P450 Enzymes and Amino Acid Biosynthesis by the Gut Microbiome: Pathways to Modern Diseases

“…Brazil is the second largest producer and exporter of soybeans in the world behind Argentina, and it has embraced genetically modified soybeans engineered to be glyphosate-tolerant as a means to increase production since the mid 1990's. A rapidly evolving glyphosate-resistant weed population in Brazil due to genetically engineered glyphosate-tolerant crops is leading to increased use of glyphosate in recent years [250], the same time period in which a rapid drop in birth rates was observed. A steady increase in the rate of preterm births in Brazil over the past two decades has been noted, although the cause remains elusive.…”

Glyphosate impairs male offspring reproductive development by disrupting gonadotropin expression

“…Glyphosate [N-(phosphonometyl)glycine] is a broad-spectrum herbicide (Hayes and Laws 1991;Cerdeira et al 2007) that is effective against weeds, especially in association with transgenic glyphosate-resistant crop systems (Cerdeira et al 2007), and represents approximately 30% of all herbicides used in agriculture (Inoue et al 2003). Even though glyphosate is considered a low-toxic herbicide, recent studies have revealed toxic effects resulting from even low-dose commercial formulations.…”

Avaliação do uso de glyphosate em soja geneticamente modificada e sua relação com o ácido chiquímico

“…Preferencialmente translocado para tecidos reprodutivos e nódulos da soja (Reddy et al, 2004), pode haver potencial efeito desse herbicida no metabolismo do nitrogênio na soja GM e, consequentemente, na sua produção (Cerdeira et al, 2007). Entretanto, os dados da Tabela 3 mostram que a produtividade de grãos não foi significativamente alterada pelas aplicações de glyphosate tanto quando aplicado isoladamente como sequencialmente.…”

“…Apesar de resistente ao glyphosate, sob determinadas condições a soja geneticamente modificada (GM) tem apresentado injúrias a aplicações desse herbicida associadas à formulação utilizada (Cerdeira et al, 2007). Muito embora não tenham sido reportadas reduções significativas na produção da soja GM, Albrecht & Ávila (2010) afirmam que aplicações de glyphosate alteraram a qualidade das sementes e seu vigor, reduzindo também a produtividade da soja GM.…”