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The molecular mechanisms of resistance in tomato induced by Pseudomonas fluorescens Sneb825 against root-knot nematode

Haiyan Fan: Shenyang Agricultural University

<div>The root-knot nematode (RKN) is one of the most seriously damaging plant-parasitic nematode in the world and threatens to the production of vegetable crops, including tomato. Biological control with microbial antagonists has received a great deal of attention as a promising measure for reducing the use of fungicides for controlling different plant diseases.<em> Pseudomonas fluorescen</em>s Sneb825 is a beneficial bacterium with high biological activity against RKN and screened from our laboratory’s biocontrol strain library with the potential applications for biocontrol of RKN. <em>P. fluorescen</em>s Sneb825 effectively inhibited <em>Meloidogyne incognita</em> infection in the split-root experiments and increased tomato plant biomass and yield of tomato in the filed experiments. The changes of lignin and ROS content in tomato roots and the expression level of their related genes were detected. The lignin content, hydrogen peroxide content, and superoxide anion radical production rate in tomato roots of irrigated treatments with the metabolite of <em>P. fluorescen</em>s Sneb825 were higher than those in controls. After inoculating with second-stage juveniles of <em>M. incognita</em>, the expression level of lignin biosynthesis related gene <em>TPX1</em>, hydrogen peroxide biosynthesis related gene <em>RBOH1</em>, and peroxidase gene<em> Ep5C </em>in irrigated treatments with the metabolite of <em>P. fluorescen</em>s Sneb825 reached the maximum level at 5, 10, and 10 days post inoculation, respectively. It suggested that a large accumulation of lignin and ROS in tomato induced by <em>P. fluorescen</em>s Sneb825 was a defense strategy to against<em> M. incognita</em>. The results of our study are beneficial to reveal the biocontrol mechanisms of <em>P. fluorescen</em>s Sneb825.</div>