The roles of abscisic acid and ethylene in cadmium accumulation and tolerance in plants

Background Cadmium (Cd) pollution in agricultural soils causes the decrease of crop yield as well as crops contamination with Cd, which then enters a food chain threatening human health. Scope The adverse effects of Cd on plant growth and development occur at the morphological, physiological, biochemical, and molecular levels and, to a large extent, explain by Cd-induced interference to regulatory networks, including those mediated by plant phytohormones. At the same time, some phytohormones such as abscisic acid (ABA) and ethylene regulate Cd accumulation and tolerance in plants. These regulatory effects are attributed to two major traits, namely control of plant redox homeostasis and reinforcement of apoplastic barrier formation at root. It is also known that ABA and ethylene interact with each other to confer plant adaptation to adverse stress conditions. Conclusion This review summarizes the current knowledge of the mechanistic basis by which ABA and ethylene assist plants in adaptation to soil Cd toxicity. This knowledge might provide clues and arm breeders with practical tools to alleviate Cd toxicity and reduce Cd accumulation in agricultural crops.