Mechanisms and applicability of nanotechnology-mediated beneficial microbes in mitigation of salinity stress in plants.

Soil salinity is a major abiotic-stress that severely impacts global agricultural productivity by reducing plant's water-uptake, causing ion toxicity, and disrupting metabolic balance. Beneficial microorganisms, including plant growth-promoting rhizobacteria (PGPR) and fungi, play a remarkable role in mitigating salt-stress through mechanisms such as osmotic adjustment, ion homeostasis, phytohormone regulation, and antioxidant defense systems. Under very high salinity, microbial inoculants also often suffer from poor survival rates, ineffective root colonization, and uneven field performance. Recent developments in nanotechnology have brought fresh approaches to maximize microbial effectiveness, therefore, offering better defense against environmental stresses and enhancing plant-microbe interactions. Under salt stress, engineered nanomaterials including nanocarriers and nano-formulations improve microbial viability, enable regulated administration, and induce biofilm formation, thereby strengthening plant resistance. Furthermore, nanoparticles enhance stress tolerance systems by modulating critical signal transduction pathways and inducing genomic and proteomic changes in microorganisms. Despite these promising benefits, concerns regarding nanoparticle toxicity, environmental persistence, regulatory challenges, and economic feasibility remain largely unaddressed. Comprehensive risk analyses and the creation of environmentally benign, biodegradable nanomaterials are necessary given the possible long-term effects mediated nanoparticles on microbial populations, soil's quality, and including crop's safety. This review explores emerging trends in nano-enabled agricultural applications, critically assesses the mechanistic contribution of nanotechnology in reducing microbial-mediated salinity stress, and addresses important issues and future research directions for the sustainable deployment of nanotechnology in plant stress management.