IntroductionGlyphosate-resistant (GR) soybeans (Glycine max) geneti-cally 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 EPSPScoding sequence derived from the common soil bacte-rium Agrobacterium spp. strain CP4 (Franz et al. 1997).Improved trait selection combined with transgenic modi-fication led to ‘second generation’ (GR2) cultivars thatwere commercially available in 2008 and promoted ashigher yielding relative to GR1 cultivars. Recent reportson plant injury in some GR soybean cultivars afterglyphosate application (Zablotowicz and Reddy 2007)stimulated greenhouse and field research showing thatphotosynthesis, plant nutrient content and biomass weresignificantly decreased in some GR1 and GR2 soybeancultivars (Zobiole et al. 2010b,c) by glyphosate applied atdifferent rates and at different soybean growth stages.In addition to affecting plant physiological functions,glyphosate may enhance higher incidence of many dis-eases as a result of the reduced nutritional status of theplant and may detrimentally impact many beneficial soilmicro-organisms (Kremer et al. 2005; Johal and Huber