Improved glyphosate resistance of 5-enolpyruvylshikimate-3-phosphate synthase from Vitis vinifera in transgenic Arabidopsis and rice by DNA shuffling

To date, only AroA variant derived from Agrobacterium tumefaciens CP4 has been used to generate the commercial glyphosate-resistant crops currently available in the market. This single source of the EPSPS gene may have caused the decrease in herbicide tolerance, which has become a major concern of those involved in field management programs. Therefore, it is of interest to increase aroA/EPSPS gene diversity and seek new glyphosate-tolerant genes for developing glyphosate-tolerant crops. In the current study, EPSPS gene from Vitis vinifera (VvEPSPS) was cloned using reverse transcription polymerase chain reaction. However, wild type VvEPSPS cannot be directly used for developing transgenic crops because of its extreme glyphosate sensitivity. Recent studies have demonstrated that DNA shuffling is an effective strategy in producing multi-mutated EPSPS resourced from plants (EPSPSplant) with improved glyphosate resistance in bacteria and plants. After performing DNA shuffling on VvEPSPS gene, one highly glyphosate-resistant mutant with seven amino acid variations was isolated after five rounds of shuffling and screening. The mutant showed seven amino acid changes in the EPSPS gene, namely, Q93R, T113A, P117L, G126A, C160Y, N239H, and V343A. The assay of glyphosate resistance further confirmed the potential of the VvEPSPS(mutant) in developing glyphosate-resistant crops.