Glyphosate-resistant (GR) soybeans (Glycine max) genetically modified to produce glyphosate-insensitive5-enolpyruvyl-shikimate-3-phosphate synthase (EPSPS)(Reddy et al. 2001) were commercialized in 1996 in US(Duke 2005). The
‘first generation’ transgenic cultivars(GR1) were developed by insertion of the cp4 EPSPS coding sequence derived from the common soil bacterium Agrobacterium spp. strain CP4 (Franz et al. 1997).Improved trait selection combined with transgenic modification led to ‘second generation’ (GR2) cultivars that were commercially available in 2008 and promoted as higher yielding relative to GR1 cultivars. Recent reportson plant injury in some GR soybean cultivars after glyphosate application (Zablotowicz and Reddy 2007)stimulated greenhouse and field research showing that photosynthesis, plant nutrient content and biomass were significantly decreased in some GR1 and GR2 soybean cultivars (Zobiole et al. 2010b,c) by glyphosate applied at different rates and at different soybean growth stages.In addition to affecting plant physiological functions,glyphosate may enhance higher incidence of many diseases as a result of the reduced nutritional status of the plant and may detrimentally impact many beneficial soil micro-organisms (Kremer et al. 2005; Johal and Huber