The effects of ethylene signaling in the cadmium-induced stress response in Arabidopsis thaliana

Abstract

Environmental pollution by cadmium (Cd) is a widespread problem, causing significant decreases in crop yield. Cadmium indirectly increases the formation of reactive oxygen species (ROS) in plants, thereby causing oxidative stress. Two important molecules involved in plant responses to Cd stress are glutathione (GSH) and ethylene. This project focused on investigating the role of ethylene signaling and its interplay with GSH in Cd-induced stress responses through a full transcriptome analysis in roots and leaves of Cd-exposed wild-type (WT) and ethylene-insensitive (ein2-1) Arabidopsis thaliana plants. The obtained results indicate that ethylene signaling is involved in a wide range of processes, including the response to Cd-induced ROS production, lipid peroxidation and ER stress. In general, differences in Cd-induced responses between WT and ein2-1 mutant plants were mostly pronounced upon acute exposure and were strongly organ-dependent. The previously hypothesized interaction between ethylene signaling and GSH was also supported by the RNA-seq data. When studying these Cd-induced effects in GSH-deficient cadmium sensitive (cad2-1) mutants, it became apparent that, where ethylene plays an important role in the early Cd-induced stress response, GSH also plays an important role in the defense upon prolonged Cd exposure. This study puts new perspectives on the role of ethylene signaling and its interaction with GSH in the Cd-induced stress response.