TMEM37 and infection: These results imply that although enhanced PR gene expression is a marker for SA-mediated resistance in early stages of e.g. viral pathogenesis (van Loon et al., 2006; Király et al., 2012; Gullner et al., 2017a; Klessig et al., 2018), in SA-deficient plants it is clearly a marker of host stress and/or a failed resistance response in advanced stages of infection.