Metabolic Pathways in Plants Under Arsenic Stress: Mechanisms, Responses, and Mitigation Strategies

Arsenic (As) is a highly toxic metalloid that can be absorbed by plants, inducing stress that disrupts vital physiological processes. In response, plants activate defense mechanisms that allow them to cope with As-induced stress. This review provides a comprehensive overview of the metabolic pathways involved in plant responses to As stress, focusing on the mechanisms of As uptake and transport, metabolic and antioxidant responses, molecular regulation, and mitigation strategies that contribute to plant adaptation and tolerance. As exposure disrupts primary metabolism by impairing photosynthesis, the Calvin cycle, and carbon and energy metabolism, while also altering aquaporin-mediated transport and phosphate homeostasis. In addition, As induces oxidative stress, leading to increased lipid peroxidation and enhanced activities of antioxidant enzymes, including superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR). It also affects secondary metabolism by modifying the biosynthesis and accumulation of specialized metabolites involved in stress tolerance. Overall, the evidence reviewed indicates that As can induce changes in both primary and secondary metabolic pathways. Although primary metabolic alterations are relatively well documented, information regarding changes in secondary metabolites, including phenolics and flavonoids, remains limited. Therefore, future research should integrate genomics, transcriptomics, proteomics, and metabolomics to elucidate the molecular basis of As tolerance and support modern crop breeding programs aimed at developing arsenic-tolerant cultivars. Moreover, this knowledge is fundamental for mitigating the impact of As on major food crops such as rice, wheat, maize, and vegetables, where arsenic contamination can reduce productivity, compromise crop quality, and increase the risk of As entry into the food chain. Furthermore, the mechanistic insights gained from these crops may serve as a basis for developing mitigation strategies applicable to other agriculturally important species.