<i>WRKY</i> Transcription Factors Shared by BTH-Induced Resistance and <i>NPR1</i>-Mediated Acquired Resistance Improve Broad-Spectrum Disease Resistance in Wheat

Abstract

In <i>Arabidopsis</i>, both pathogen invasion and benzothiadiazole (BTH) treatment activate the <i>nonexpresser of pathogenesis-related genes 1</i> (<i>NPR1</i>)-mediated systemic acquired resistance, which provides broad-spectrum disease resistance to secondary pathogen infection. However, the BTH-induced resistance in Triticeae crops of wheat and barley seems to be accomplished through an <i>NPR1</i>-independent pathway. In the current investigation, we applied transcriptome analysis on barley transgenic lines overexpressing wheat <i>wNPR1</i> (<i>wNPR1-OE</i>) and knocking down barley <i>HvNPR1</i> (<i>HvNPR1-Kd</i>) to reveal the role of <i>NPR1</i> during the BTH-induced resistance. Most of the previously designated barley chemical-induced (<i>BCI</i>) genes were upregulated in an <i>NPR1</i>-independent manner, whereas the expression levels of several pathogenesis-related (<i>PR</i>) genes were elevated upon BTH treatment only in <i>wNPR1-OE.</i> Two barley <i>WRKY</i> transcription factors, <i>HvWRKY6</i> and <i>HvWRKY70</i>, were predicted and further validated as key regulators shared by the BTH-induced resistance and the <i>NPR1</i>-mediated acquired resistance. Wheat transgenic lines overexpressing <i>HvWRKY6</i> and <i>HvWRKY70</i> showed different degrees of enhanced resistance to <i>Puccinia striiformis</i> f. sp. <i>tritici</i> pathotype CYR32 and <i>Blumeria graminis</i> f. sp. <i>tritici</i> pathotype E20. In conclusion, the transcriptional changes of BTH-induced resistance in barley were initially profiled, and the identified key regulators would be valuable resources for the genetic improvement of broad-spectrum disease resistance in wheat.[Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.