Selenium nanoparticles from Dermacoccus abyssi MT1.1ᵀ improve water status, biomass, and antioxidant defense in...

Salt stress severely limits plant growth and agricultural productivity. Nanoparticles have emerged as a promising strategy to alleviate salinity stress. This study investigated the biogenic synthesis of selenium nanoparticles (SeNPs) using the culture supernatant of Dermacoccus abyssi MT1.1^T and evaluated their effects on tomato germination and seedling growth under salt stress. Successfully synthesized SeNPs were spherical, nanoscale, negatively charged, and moderately stable. Application of SeNPs at 5 mg mL^-1 showed no phytotoxic effects on tomato germination under 50, 100, and 150 mM NaCl. Under 150 mM NaCl, SeNP-treated seedlings exhibited increased fresh and dry weights and enhanced accumulation of proline and total soluble sugars, leading to improved relative water content. Furthermore, SeNPs alleviated salt-induced oxidative stress by reducing hydrogen peroxide levels and enhancing antioxidant enzymes, including catalase and guaiacol peroxidase. These findings highlight biogenic SeNPs from D. abyssi MT1.1^T as a potential eco-friendly nanobiostimulant for improving tomato salt tolerance.