Carbon nanotube-mediated drought stress mitigation in plants through morphological, physiological and biochemical mechanisms

Carbon nanotubes (CNTs) have been explored as a promising approach to improve plant drought resilience by regulating various morphological, physiological, and biochemical processes. Morphologically, CNTs have the ability to infiltrate root tissues, creating nano-channels that may improving water and nutrients uptake. On the Physiological level, these nanomaterials can affect plant hormone signaling by modifying the concentrations of essential hormones such as abscisic acid (ABA), auxins, cytokines, and gibberellins, thereby stimulating cell and root development, and stress resilience. CNTs improve the efficiency of photosynthesis by enhancing chlorophyll fluorescence, chlorophyll content, promoting electron flow, and crucial enzymes activity such as Rubisco and phosphoenolpyruvate carboxylase (PEPC), which are essential for effective CO₂ fixation and photosynthesis assimilation. Biochemically, CNTs mitigate drought-induced oxidative stress by upregulating antioxidant enzymes, managing reactive oxygen species (ROS) levels, and adjusting osmoprotectants like proline and sugars. However, research on CNTs and their impact remains limited,, underscoring the necessity for more thorough exploration of their mechanisms, safety, and long-term effects. This review explores the morphological, physiological and biochemical mechanisms that contribute to CNT-induced stress tolerance in plants, with a particularly focusing on their ability to improve drought resistance. Furthermore, the phytotoxicity effects linked to CNT exposure was discussed. In addition, the limitations and future opportunities for employing CNTs in sustainable agriculture were outlined, covering safety aspects, cost-effectiveness, and environmental sustainability.