Maize Genomics and Genetics 2024, Vol.15, No.2, 60-69 http://cropscipublisher.com/index.php/mgg 62 Figure 1 In silico analysis and identification of glyphosate-resistant (GR) mutations site (Adopted from Sony et al., 2023) Image caption: A: The conserved amino acid (G172, T173, and P177) sites in EPSPS protein of different plants (B) Phylogenetic analysis of EPSPS protein of different plants; C: (a) Wild structure of EPSPS protein in ribbon-like representation with positioning of selected amino acid to edit; (b) Mutant structure of EPSPS protein in ribbon-like representation with positioning of selected amino acid to edit; (c) Superpositioned structure of mutant and WT EPSPS proteins for geometrical projections; Position of 172, 173, and 177 amino acids are highlighted as blue, yellow, and red, respectively; D: (a) Active site volume of wild EPSPS protein, highlighting the selected three amino acids to edit; (b) The area of the volume within the selected amino acids. (c) Active site volume of Mutant EPSPS protein, highlighting the selected three amino acids to edit; (d) The area of the volume within the selected amino acids. (e) Two-dimensional structure of PEP, mentioning the position of phosphate, amino, and carboxyl group; (f) Two-dimensional structure of glyphosate, mentioning the position of phosphate, amino, and carboxyl group; E: (a) Active site volume of wild EPSPS protein, highlighting the selected three amino acids to edit; (b) The area of the volume within the selected amino acids; (c) Active site volume of mutant EPSPS protein, highlighting the selected three amino acids to edit; (d) The area of the volume within the selected amino acids; (e) Two-dimensional structure of PEP, mentioning the position of the phosphate, amino, and carboxyl group; (f) Two-dimensional structure of Glyphosate, mentioning the position of phosphate, amino, and carboxyl group (Adopted from Sony et al., 2023) Genetic engineering techniques, including transgenic approaches and genome editing, have significantly advanced the development of herbicide-tolerant maize. Key genes such as EPSPS and bar play crucial roles in conferring resistance to glyphosate and glufosinate, respectively, while the integration of additional genes like igrA can further enhance tolerance and reduce herbicide residues. These advancements hold great promise for improving weed management and crop productivity in maize. 3 The Impact of Genetic Engineering on Maize Herbicide Tolerance 3.1 Historical development of herbicide-tolerant maize The development of herbicide-tolerant maize has been a significant milestone in agricultural biotechnology. The initial efforts focused on creating maize varieties that could withstand specific herbicides, thereby simplifying weed management and reducing crop damage. Early genetically engineered (GE) maize varieties were primarily
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