Unleashing the Potential of Engineered Nanoparticles in Mitigating Abiotic Stress in Plants: A Review

Abiotic stress is a major problem which threatens agricultural productivity and global food security. Drought, extreme temperatures, salinity, and heavy metal contaminations cause disturbances in plant cellular homeostasis, impair metabolic processes, and reduce crop yields. Plants possess innate defense mechanisms against abiotic stresses by expressing stress-responsive genes, accumulating osmo-protectants, and the activation of antioxidant enzymes. Failure of these defense mechanisms under prolonged stress conditions leads to homeostatic imbalances. Recently, nanotechnological approaches like nanoparticle-mediated delivery systems have been developed to enhance the plants' resilience against stress conditions. Engineered nanoparticles (ENPs) have unique physicochemical properties such as a high surface area, high reactivity, and a tunable surface chemistry. These properties enable the nanoparticles to interact with plant systems at molecular and cellular levels, modulate stress signaling pathways, trigger the upregulation of stress-responsive genes, and reduce oxidative stress by increasing antioxidant enzymes' activity. However, under certain environmental conditions, ENPs may also induce oxidative damages and exhibit phytotoxicity. This review encompasses a comprehensive overview on the role of nanoparticles in abiotic stress management, along with detailed insights into the biosafety and environmental toxicity of ENPs. Overall, the review highlights the novel insights of ENPs-plant interactions and identifies existing knowledge gaps through a systematic literature review to guide future research towards sustainable agriculture.