DEVELOPMENT, IDENTIFICATION, AND CHARACTERIZATION OF A GLYPHOSATE-TOLERANT SOYBEAN LINE

Glyphosate (N-phosphonomethyl-glycine) is the active ingredient in the nonselective herbicide Roundup. The sensitivity of crop plants to gly phosate has limited its in-season use as a postemergence herbicide. Th e extension of the use of Roundup herbicide to allow in-season applica tion in major crops such as soybeans [Glycine mar (L.) Merr.] would pr ovide nerv weed control options for farmers. A glyphosate-tolerant soy bean line, 40-3-2, was obtained through expression of the bacterial 5- enolpyruvylshikimate-3-phosphate synthase (EPSP synthase, EPSPS) enzym e from Agrobacterium sp. strain CP4. Line 40-3-2 is highly tolerant to glyphosate, showing no visual injury after application of up to 1.68 kg acid equivalent (a.e.) ha(-1) of glyphosate under field conditions. Molecular characterization studies determined that the single genetic insert in fine 40-3-2 contains only a portion of the cauliflower mosa ic virus 35S promoter (P-E35S), the Petunia hybrida EPSPS chloroplast transit peptide (CTP), the CP4 EPSPS gene, and a portion of the 3' non translated region of the nopaline synthase gene (NOS 3') terminator. I nheritance studies have shown that the transgene behaves as a single d ominant gene and is stable over several generations.