In maize, co-expression of GAT and GR79-EPSPS provides high glyphosate resistance, along with low glyphosate residues
Researchers from the Biotechnology Research Institute in the Chinese Academy of Agricultural Sciences have successfully developed a new bio-breeding resource for glyphosate-resistant (GR) maize by introducing the microbial genes GAT and GR79-EPSPS.
Herbicide tolerant crops, including glyphosate tolerant crops, offer an innovative solution that can help farmers in weed control management. Million hectares of farmlands are affected by weed infestation yearly all over the world. If left untreated, weed infestation can result in a significant decrease in crop production and yield.
To address this challenge, the researchers introduced a codon-optimized glyphosate N-acetyltransferase gene (GAT) and the enolpyruvyl-shikimate-3-phosphate synthase gene (GR79-EPSPS) into the maize variety B104. A genetically stable high glyphosate resistance transgenic event, designated GG2, was selected from the transgenic maize population through screening with high doses of glyphosate.
The results of the study show that the co-expression of GAT and GR79-EPSPS provides high glyphosate resistance. The findings in the field trials indicate that the transgenic maize event GG2 could tolerate 9000 g acid equivalent (a.e.) glyphosate per hectare or 10 times the recommended glyphosate dose with no negative effect on phenotype or yield. Additionally, the glyphosate (PMG) and aminomethylphosphonic acid (AMPA) residues in GG2 leaves are reduced by more than 90% compared to the levels in HGK60 transgenic plants.