Convenient Assay of O2-Generated on Potato Tuber Tissue Slices Treated with Fungal Elicitor by Electron Spin Resonance - No Secondary Oxidative Burst Induction by H2O2Treatment

Abstract

Since the discovery of generation of <TEX>$O_2^-$</TEX> in plant, many evidence for the oxidative burst (OXB) has been accumulated in various combinations of plant and pathogen or elicitor systems. <TEX>$O_2^-$</TEX> generating system responsible for the OXB was coupled with oxidation of reduced nicotinamide adenine dinucleotide phosphate (NADPH) in microsomal fraction isolated from sliced aged potato tuber slices which were treated by hyphal wall components elicitor from Phytophthora infestans (HWC). We developed new assay method for quantitative measurement of oxygen radical <TEX>$O_2^-$</TEX> by using electron spin resonance (ESR) analysis during elicitor­induced OXB on the surface of plant tissues. The ESR analysis using an <TEX>$O_2^-$</TEX> trapper, Tiron (1,2-dihydroxy-3,5­benzenedisulfonic acid), provided a convenient assay for detecting only <TEX>$O_2^-$</TEX> during elicitor-induced OXB producing various active oxygen species (AOS) on plant tissue surface. Tiron was oxidized to Tiron semiquinon radical by <TEX>$O_2^-$</TEX>. Quantity of the radical signal was measured by specific spectra on ESR spectroscopy. The level of <TEX>$O_2^-$</TEX> was high in from surface of potato tuber tissue treated with hyphal cell wall elicitor (HWC) from Phytophthora infestans. There was no secondary OXB induction by <TEX>$H_2O_2$</TEX> treatment in plant.