PHYSIOLOGICAL RESPONSES INDUCED BY ENDOPLASMIC RETICULUM STRESS IN PLANTS EXPOSED TUNICAMYCIN AND DITHIOTHREITOL

Abstract

Endoplasmic reticulum (ER) stress is characterized by an accumulation of unfolded proteins induced by several adverse conditions, such as drought, salinity, and pathogens. Both tunicamycin (TM) and dithiothreitol (DTT) are applied to study the ER stress in plants. Although there is not a consensus of the concentration and chemicals used as well as physiological markers, it triggers the unfolded protein response (UPR) composed by sensors into the ER membrane, which start a signaling process to restore homeostasis or induce cell death. In this way, this review includes the advances in the knowledge of ER response induced by TM and DTT treatments, especially their downstream physiological effects. From low TM (≤ 0.5 µg ml-1) and DTT (0.5 to 1.0 mM) concentrations, the chlorophyll loss is linked to reactive oxygen species (ROS), and SA and JA signaling that result in growth impairment associated with UPR genes unbalance. Above 0.5 μg.ml-1 of TM or 1.0 mM DTT, a ROS cytoprotective role is crucial to stress acclimation or cell death. From 1.0 to 10 μg.ml-1 TM or 2.0 to 10 mM DTT, necrotic lesions are linked to electrolyte leakage, and fatty acid oxidation, which was more aggravated/intense at high concentration (50 and 200 μg.ml-1). Overall, this work associates crescent concentrations of two ER stressors and its downstream physiological responses, which helps to elucidate possible mechanisms to adjust to environmental stresses starting the mechanisms of adaptation to survival or death.