Estimating the role of maize Y-EPSPS gene in glyphosate resistance in Arabidopsis transgenic lines

Abstract

The herbicide glyphosate inhibits the key enzyme 5-enolpyruvate shikimate-3-phosphate synthase (EPSPS) in the aromatic amino acid synthesis pathway of plants. This study aims to explore the Y-EPSPS gene derived from maize through codon optimization and validate its glyphosate resistance in Arabidopsis Thaliana. Germination rates of seeds under different glyphosate concentrations revealed that seeds overexpressing the Y-EPSPS gene exhibited higher germination rates compared to wild-type seeds. DAB and NBT staining methods were used to measure ROS levels in Arabidopsis plants under 0.8 mM glyphosate stress, showing that plants overexpressing Y-EPSPS had lower ROS levels compared to wild-type plants. Soluble sugar and malondialdehyde (MDA) content were higher in Y-EPSPS overexpressing plants, whereas MDA content was lower, indicating a potential stress response to glyphosate. Chlorophyll content and FV/FW ratio were higher in plants overexpressing Y-EPSPS compared to wild-type plants, suggesting reduced susceptibility to glyphosate. Enzyme activity and gene expression analysis further demonstrated significant increases in POD, SOD, and CAT enzyme activities in Y-EPSPS overexpressing plants compared to wild-type, while SD enzyme activity decreased significantly. Expression levels of ROS detoxification-related genes (AtCAT3 and AtSOD1) and stress defense-related genes (AtLTP3, AtSOS1, and DQSD) were also elevated to varying degrees in Y-EPSPS overexpressing plants compared to wild-type plants. These results indicate that the optimized Y-EPSPS gene confers certain resistance to glyphosate.