This article explores the molecular behavior of plants in response to heavy metals (HMs), focusing on their criticality and toxicity. It discusses the sources, occurrence, and agroecological impacts of HMs in soil, as well as the plant's response mechanisms, including the role of transporters and molecular responses. HMs, such as Cu, Zn, Mn, Mo, Fe, and Ni, are essential for plant growth, while others like Al, Cd, Cr, Pb, and Hg are toxic. The article highlights the negative effects of HMs on plant health, including oxidative stress, DNA damage, and disrupted physiological processes. Plants have developed various strategies to tolerate HMs, such as the sequestration of metals into vacuoles, the synthesis of phytochelatins and metallothioneins, and the activation of stress proteins. The article also discusses the role of metal transporters in the uptake, sequestration, and detoxification of HMs, as well as the impact of HMs on seed germination and plant growth. The beneficial roles of certain HMs, such as Cu, Zn, Mn, Mo, Fe, and Ni, are also reviewed, along with the concept of hormesis and cross-tolerance. The study emphasizes the importance of understanding the molecular and biochemical responses of plants to HMs for developing strategies to mitigate their toxic effects and improve agricultural productivity.This article explores the molecular behavior of plants in response to heavy metals (HMs), focusing on their criticality and toxicity. It discusses the sources, occurrence, and agroecological impacts of HMs in soil, as well as the plant's response mechanisms, including the role of transporters and molecular responses. HMs, such as Cu, Zn, Mn, Mo, Fe, and Ni, are essential for plant growth, while others like Al, Cd, Cr, Pb, and Hg are toxic. The article highlights the negative effects of HMs on plant health, including oxidative stress, DNA damage, and disrupted physiological processes. Plants have developed various strategies to tolerate HMs, such as the sequestration of metals into vacuoles, the synthesis of phytochelatins and metallothioneins, and the activation of stress proteins. The article also discusses the role of metal transporters in the uptake, sequestration, and detoxification of HMs, as well as the impact of HMs on seed germination and plant growth. The beneficial roles of certain HMs, such as Cu, Zn, Mn, Mo, Fe, and Ni, are also reviewed, along with the concept of hormesis and cross-tolerance. The study emphasizes the importance of understanding the molecular and biochemical responses of plants to HMs for developing strategies to mitigate their toxic effects and improve agricultural productivity.