Suppression of glyphosate toxicity in plants following peroxide treatment

Abstract

Food production is affected by rise in population, infertile soil, and water scarcity. Wheat and legumes are the major crops globally, but often encounter reduced growth due to various chemical and environmental stresses. The 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase is a key enzyme in the biosynthetic pathway of aromatic amino acid in plants and microbes. Glyphosate is a broad spectrum, non-selective herbicide, which acts as an inhibitor of EPSP. In contrast, reactive oxygen species (ROS) generated by hydrogen peroxide (H₂O₂) in soil is thought to provide growth stimulation in plants. It has been postulated that the oxidation of glyphosate may occur through ROS generated by H₂O₂ that acts as electron acceptor and may work via the modulation of EPSP and its degradation. Therefore, in this work in silico molecular docking studies were conducted showing blockade in the active cavity of EPSP by H₂O₂ that prevented the binding of glyphosate. The key amino acid residues of EPSP involved in the binding with glyphosate are His-385 and Lys-411, while H₂O₂ hinders the interaction of glyphosate with the aforesaid residues. The ERRAT plot provided 97.608 score and RAMPAGE displayed no outliers, which showed the validity of the modified 1G6S PDB structure of EPSP. In vivo studies further corroborated the inhibition of glyphosate by H₂O₂ and also growth promotion. This study provides a novel way to counteract glyphosate toxicity to commercially important crops.

Keywords:

• degradation
• glyphosate
• hydrogen peroxide
• reactive species
• in silico

Acknowledgments

We want to pay sincere thanks to Dr Hamendra Singh Parmar for his intellectual help at every step of my project. His practical and experimental abilities made me solve some unavoidable questions raised by these experiments. We are very thankful to Ms Neha Barve for her in silico support and for making us understand minuteness of the software and their usage.