INVESTIGATING DISEASE RESISTANCE IN EUTREMA SALSUGINEUM & THE ESTABLISHMENT OF A EUTREMA-P. SYRINGAE PLANT PATHOSYSTEM

Abstract

<p><em>Eutrema salsugineum</em> is an extremophile plant native to the Yukon Territory and coastal China. As an extremophile, Yukon <em>Eutrema</em> is tolerant to highly saline, drought conditions and cold temperatures while Shandong <em>Eutrema</em> can survive in highly saline conditions (Griffith et al., 2007; Guevara et al., 2012; Inan et al., 2004). The disease resistance responses of the Yukon and Shandong accessions of <em>Eutrema</em> were investigated to understand how an abiotic stress-tolerant plant responds to biotic stress. A pathosystem was developed using <em>Pseudomonas</em> <em>syringae</em> pv. <em>tomato</em> DC3000 (<em>Pst</em>) to examine <em>Eutrema</em> defense responses. Compared to <em>Arabidopsis </em>(Col-0), both <em>Eutrema</em> accessions exhibited resistance to <em>Pst,</em> with Shandong <em>Eutrema</em> displaying greater resistance than Yukon <em>Eutrema</em>. Resistance to <em>P. syringae</em> pv. <em>maculicola</em> (<em>Psm</em>) was also observed in both accessions. Furthermore, both <em>Eutrema</em> accessions displayed a differential capacity for effector-triggered immunity (ETI). RNA-Seq data of uninoculated Shandong vs. Yukon <em>Eutrema</em> revealed an overrepresentation of defense genes including <em>PR1</em> (<em>pathogenesis-related1</em>; Champigny et al., 2013). Expression of the <em>Eutrema</em> <em>PR1</em> ortholog in uninoculated Shandong leaves combined with enhanced resistance to <em>Pst</em> compared to Yukon <em>Eutrema</em> or Col-0 <em>Arabidopsis</em> suggests that Shandong plants exist in a defense-primed state. Resistance to other pathogens such as <em>Pectobacterium</em> <em>carotovorum</em> ssp. <em>wasabiae</em> (<em>Pcw</em>) further supported the hypothesis that Shandong <em>Eutrema</em> is primed for pathogen tolerance. The <em>Eutrema</em>-<em>P. syringae</em> pathosystem will facilitate future studies to understand how <em>Eutrema</em> deals with multiple or concurrent stresses and this knowledge will contribute to efforts to improve tolerance to both abiotic and biotic stress in crop plants.</p>