DOI: https://doi.org/10.5513/JCEA01/27.3.5193
Review article
Plant defense mechanisms against heavy metal stress
2026, 27 (3) p. 824-838
Abstract
Heavy metal toxicity adversely affects key physiological processes in plants, including photosynthesis and respiration, resulting in reduced plant growth, development, and productivity. Plants manage the negative effects of heavy metal toxicity through a complex set of mechanisms that can be categorized into two main strategies: avoidance strategy and tolerance strategy. The avoidance strategy serves as the initial defence line for plants facing heavy metal toxicity, showcasing their ability to avert or block the entry of heavy metal ions into the plant. The key mechanisms involved in heavy metal avoidance include the immobilization of heavy metals through root exudates or mycorrhizal associations and the incorporation of heavy metals into the root cell walls. In contrast, the tolerance strategy encompasses all mechanisms that a plant activates when heavy metal ions have already been absorbed, aiming to reduce or neutralize their negative effects. These mechanisms involve the overexpression of genes associated with heavy metal tolerance, along with metal chelation by phytochelatins and metallothioneins, followed by their compartmentalization in the vacuole. Understanding all of these defence mechanisms, as well as the signalling pathways involved in plants’ responses to heavy metal stress, is critical for developing strategies to increase crop resilience to heavy metal-contaminated environments.
Keywords
avoidance, chaperons, chelation, compartmentalization, tolerance
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