Effects of Plant Hormones on Cadmium Stress and Signaling Mechanisms

Cadmium (Cd) is a non-essential heavy metal that significantly threatens plant growth and development. Plant hormones mediate plant responses to Cd stress, acting as signaling molecules that orchestrate a complex network of adaptive mechanisms. This review focuses on ethylene, a gaseous plant hormone, in the plant response to Cd stress. It explores how Cd influences ethylene biosynthesis, particularly ACC synthase (ACS) and ACC oxidase (ACO) activity, and the subsequent signaling pathways that mediate Cd stress responses. Ethylene's multifaceted role in regulating various physiological and molecular processes under Cd stress, including root and shoot growth, oxidative stress, and metal detoxification, is discussed. The review further highlights the intricate crosstalk between ethylene and other key phytohormones, such as auxin, cytokinin, ABA, and JA, in fine-tuning the plant's adaptive coping strategies for Cd toxicity. Finally, the article delves into potential biotechnological applications of this knowledge, including genetic engineering, ACC deaminase-producing bacteria, and ethylene-based phytoremediation strategies. This review emphasizes the potential of understanding ethylene's complex role in Cd stress responses for developing more resilient crops and practical remediation approaches for Cd-contaminated environments.