Plants glyphosate-resistant

FIGURE 9-31 Glyphosate-resistant soybean plants. The photographs... 

Baerson, S.R., D.J. Rodriguez, M. Tran, Y. Feng, N.A. Biest, and G.M. Dill (2002). Glyphosate-resistant goosegrass Identification of a mutation in the target enzyme 5-enolpyruvylshikimate-3-phosphate synthase. Plant Physiol., 129 1265-1275. 

The advantage for the farmer is that he needs only one product, instead of several different selective (and more expensive) herbicides. Roundup ready soybeans were launched in 1996 and today 50 percent of the soybean crop in the United States is derived from roundup ready seeds. Other glyphosate-resistant transgenic crops introduced by Monsanto are maize and oil seed rape. Competing companies also developed herbicide-resistant plants or plants genetically modified to be protected against certain pests, but none has achieved a commercial breakthrough, mainly because of political reasons. 

Atrazine resistance and plants made resistant by genetic engineering Resistance to glyphosate 9.3.5.1 Summary... 

A major milestone occurred in 1996 with the commercial introduction of glyphosate resistant soybean [22]. Since then, the glyphosate resistant trait (Roundup Ready , RR) has been introduced into canola, cotton, com, alfalfa, sugar beet, and others. All RR crops thus far contain a glyphosate insensitive EPS PS derived either from the plant or bacteria. 

Table 6.2.1 Comparison of steady state kinetics of EPSPS enzymes from plant and bacteria that are used to engineer glyphosate resistance in crops.

Taken together, the investigation of glyphosate resistance, both in cultured plant cells and in bacteria, supports the conclusion that EPSP synthase is a major target of glyphosate. While no glyphosate-resistant plant EPSP synthase has been identified, current efforts are directed towards the transformation of crop plants with... 

Greenhouse Study. This research conclusively confirmed that the suspected glyphosate-resistant horseweed is resistant to glyphosate (Table I). Visual evaluations at 14 d indicated less than 15% control in resistant populations, while the susceptible plants showed 99% control. 

Glyphosate horseweed from Delaware has previously been examined to elucidate the resistance mechanism (20). Initial indications are that glyphosate uptake into the plant and subsequent translocation to the active site were not responsible for the observed resistance. However, enhanced glyphosate metabolism was also not implicated in this preliminary report. A hypothesis of this research group (20) was that an altered form of the EPSPS enzyme was present in glyphosate-resistant horseweed, although the plants retained some susceptible isoforms of the same enzyme. 

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