Regulation of arsenic stress response by ethylene biosynthesis and signaling in Arabidopsis thaliana
Nivedita Singh, Subhash Reddy Gaddam, Deeksha Singh, Prabodh Kumar Trivedi
Abstract
Ethylene, a plant hormone, regulates several biological processes and plant stress responses. Studies suggest that though ethylene production increases, plant growth is reduced during stress conditions. Though there are a few studies showing the involvement of ethylene in heavy metal stress, not much is known about its involvement in arsenic (As) stress. In this study, the role of ethylene in As stress response has been studied in Arabidopsis thaliana. Six ethylene biosynthesis and signaling mutants showed a differential response towards As stress. Out of different mutants, the mutation in ARABIDOPSIS ETHYLENE OVERPRODUCER 1 (eto1−1) and CONSTITUTIVE TRIPLE RESPONSE1 (ctr1-10) provided tolerance; however, ETHYLENE-INSENSITIVE PROTEIN 2 (ein2-T) was the most sensitive. The percentage root reduction, arsenic estimation, superoxide and hydrogen peroxide accumulation showed the tolerant nature of eto1-1 and ctr1-10. The expression of genes involved in arsenic detoxification, sulfur transport was more in eto1-1 and ctr1-10 compared to the sensitive mutant, ein2-T. The expression of genes involved in glutathione (GSH) biosynthesis and the use of a GSH biosynthesis inhibitor suggest a GSH-dependent pathway regulated by ethylene during As stress. In conclusion, our study suggests that ethylene biosynthesis and signaling play an important role in As response in Arabidopsis.