Effects of Jasmonic Acid in ER Stress and Unfolded Protein Response in Tomato Plants

Abstract

Endoplasmic reticulum (ER) stress elicits a protective mechanism called unfolded protein response (UPR) to maintain cellular homeostasis, which can be regulated by defence hormones. In this study, the physiological role of jasmonic acid (JA) in ER stress and UPR signalling has been investigated in intact leaves of tomato plants. Exogenous JA treatments not only induced the transcript accumulation of UPR marker gene SlBiP but also elevated transcript levels of SlIRE1 and SlbZIP60. By the application of JA signalling mutant jai1 plants, the role of JA in ER stress sensing and signalling was further investigated. Treatment with tunicamycin (Tm), the inhibitor of N-glycosylation of secreted glycoproteins, increased the transcript levels of SlBiP. Interestingly, SlIRE1a and SlIRE1b were significantly lower in jai1. In contrast, the transcript accumulation of Bax Inhibitor-1 (SlBI1) and SlbZIP60 was higher in jai1. To evaluate how a chemical chaperone modulates Tm-induced ER stress, plants were treated with sodium 4-phenylbutyrate, which also decreased the Tm-induced increase in SlBiP, SlIRE1a, and SlBI1 transcripts. In addition, it was found that changes in hydrogen peroxide content, proteasomal activity, and lipid peroxidation induced by Tm is regulated by JA, while nitric oxide was not involved in ER stress and UPR signalling in leaves of tomato.

Activation of Local and Systemic Defence Responses by Flg22 Is Dependent on Daytime and Ethylene in Intact Tomato Plants

“…Data were evaluated by the AXIOVISION REL. 4.8 software (Carl Zeiss Inc., Munich, Germany) [ 117 , 118 ]. Leaves of three different plants were used for sampling in the case of each treatment.…”

Role of ethylene in ER stress and the unfolded protein response in tomato (Solanum lycopersicum L.) plants

“…Six-week-old tomato plants in hydroponic culture were used for all experiments. The nutrient solution was changed three times per week according to Czékus et al (2020). The conditions of the controlled environment used for plant growing were as follows: photon flux density (Osram Sylvania, Danvers, MA, USA), 200 μmol m − 2 s − 1 ; light/dark cycle, 12/12 h; day/night temperatures, 24/22 • C; and relative humidity, 55%-60%.…”

“…Tomato plants at the five-leaf stage were treated with the ET precursor ACC at concentrations of 0.1 or 1 mM (Borbély et al, 2019) or with the ER stress-inducing agent tunicamycin (Tm) at 0.5 μg mL − 1 via their addition into the nutrient solution (Watanabe and Lam, 2008). To estimate the direct effects of Tm on the induction of ER stress, 1 mM sodium 4-phenylbutyrate (PBA; as a widely used chemical chaperone) was also added into the nutrient solution in the presence or absence of Tm (Czékus et al, 2020). All chemicals were purchased from Sigma-Aldrich (St. Louis MO, USA).…”

“…RNA extraction and analysis of gene expression were performed as described by Czékus et al (2020). The genomic DNA was eliminated by digestion with DNase I (Thermo Scientific, Waltham, MA, USA).…”

“…Traditionally, salicylic acid (SA), jasmonic acid (JA), ethylene (ET), and abscisic acid are considered as the main defense-related or stress hormones in plants ( Bari and Jones, 2009). The role of SA in ER stress and UPR is the topic that has been investigated the most in this context (Nagashima et al, 2014;Poór et al, 2019), and there is some relevant information about the role of JA in this process (Xu et al, 2019;Czékus et al, 2020). Nevertheless, the role of ET in the UPR remains mostly unclear but has been postulated as a fine-tuner of the activation of tolerance or PCD (Depaepe et al, 2021).…”