Nanoparticle-mediated enhancement of plant tolerance to combined abiotic stresses: Mechanisms and applications

Plants are exposed to an increasing number of complex abiotic stresses such as drought, salt, extreme temperatures and heavy metal contamination which often occur in combination and severely inhibit growth, development and crop yield. These stresses affect water and nutrient uptake, photosynthesis, cause oxidative damage, produce reactive oxygen species (ROS), and affect hormonal and metabolic systems. Conventional approaches such as selective breeding and agronomic manipulations do not provide significant relief under multifactorial stress conditions. Nanoparticles (NPs) have unique physicochemical properties like high surface area, reactivity and tunable surface chemistry that allow their interaction with plants at physiological, biochemical and molecular levels. Thus, nanotechnology is a promising alternative. The engineered nanoparticles can enhance water and nutrient uptake, serve as antioxidants, stabilize cellular osmotic equilibrium and modify stress-responsive gene expression. Recent studies have shown that these nanoparticles may induce tolerance to combined stress conditions, but the vast majority of studies have been limited to single-stress scenarios. This mini-review highlights the recent advances in nanoparticle-mediated plant stress tolerance and discusses the mechanisms, potential agricultural applications, and challenges and future prospects for sustainable crop production.