**Péter Poór \*, Zalán Czékus, Irma Tari and Attila Ördög**

Department of Plant Biology, University of Szeged, Közép fasor 52, H-6726 Szeged, Hungary **\*** Correspondence: poorpeti@bio.u-szeged.hu; Tel.: +36-62-544-307

Received: 18 October 2019; Accepted: 19 November 2019; Published: 21 November 2019

**Abstract:** Different abiotic and biotic stresses lead to the accumulation of unfolded and misfolded proteins in the endoplasmic reticulum (ER), resulting in ER stress. In response to ER stress, cells activate various cytoprotective responses, enhancing chaperon synthesis, protein folding capacity, and degradation of misfolded proteins. These responses of plants are called the unfolded protein response (UPR). ER stress signaling and UPR can be regulated by salicylic acid (SA), but the mode of its action is not known in full detail. In this review, the current knowledge on the multifaceted role of SA in ER stress and UPR is summarized in model plants and crops to gain a better understanding of SA-regulated processes at the physiological, biochemical, and molecular levels.

**Keywords:** binding protein; cell death; pathogenesis-related genes; systemic acquired resistance; tunicamycin
