Ethylene mediates dichromate-induced oxidative stress and regulation of the enzymatic antioxidant system-related transcriptome in Arabidopsis thaliana

Abstract

Dichromate [Cr(VI)] induces phytotoxicity either directly by interfering in a plant’s physiological, biochemical, and/or molecular process or indirectly by stimulating reactive oxygen species accumulation (ROS). The underlying mechanism in Cr(VI)-induced ROS mediated phytotoxicity is elusive. In the current study, we investigate the possibility that Cr(VI)-induced alteration in the total biomass production, cell/tissue viability, and cell cycle-related transcriptome is mediated by the accumulation of high ROS level and that ethylene participates in this process. We showed that high Cr(VI) level reduces total biomass, chlorophyll contents, cell/tissue viability, and expression of cell cycle-related genes. Consistently, the oxidative damage and ROS accumulations were significantly increased in the seedlings exposed to higher Cr(VI) concentrations. Furthermore, Cr(VI)-induced EBS::GUS activity and expression level of ethylene signaling and biosynthesis related genes were also reported in the current study. Moreover, Cr(VI)-induced ROS accumulation by down-regulating enzymatic antioxidant system-related genes was slightly increased by the application of exogenous ethylene precursor (ACC), while significantly reduced by ethylene perception and biosynthesis antagonists silver (Ag) and cobalt (Co) respectively. Taken together, our results showed that ethylene mediates dichromate induced ROS accumulation by suppressing the expression level of enzymatic antioxidant enzymes-related genes.