Hydrogen Peroxide Measurement in Arabidopsis Root Tissue Using Amplex Red

This protocol describes the measurement of hydrogen peroxide (H2O2) content in Arabidopsis root tissue by using the Amplex® Red Hydrogen Peroxide/Peroxidase Assay Kit. When root tissue is disrupted and resuspended in phosphate buffer, H2O2 is released from the cells. The obtained root extracts containing H2O2 can be mixed with a solution containing Amplex® Red reagent (10-acetyl-3,7-dihydrophenoxazine). In the presence of horseradish peroxidase, the Amplex® Red reagent reacts with H2O2 in a 1:1 stoichiometry. The resulting product is the red-fluorescent compound resorufin which can be detected fluorometrically or spectrophotometrically. Our protocol is based on the manual of the Amplex® Red Hydrogen Peroxide/Peroxidase Assay Kit and describes a step-by-step procedure with a detailed description of the necessary controls and data analysis. We have also included modifications of the protocol, notes and examples that intend to aid the user in easily reproducing the assay with their own samples.