Manganese Nanoparticles Control Salinity-Modulated Molecular Responses in Capsicum annuum L. through Priming: A Sustainable Approach for Agriculture

The application of nanomaterials as a method to overcome plant stress and increase crop yield is relatively new as compared to the use of fertilizers and pesticides in agricultural production. In the present study, manganese (III) oxide nanoparticles (MnNPs) were investigated as a nanopriming agent to alleviate salinity stress in Capsicum annuum L. during germination at 100 mM NaCl. In general, the root growth in both nonsalt and salt-stressed seedlings was significantly improved by MnNPs (0.1, 0.5, 1 mg/L). Scanning electron microscopy and energy-dispersive spectroscopy showed the penetration of MnNPs through the seed coat and the formation of nanoparticle–corona complex. MnNPs have different surface chemistries when present in water or NaCl, which may lead to their different affinities to proteins and alter the N–H bonding according to Fourier transform infrared spectroscopy. Salt stress inhibited root growth, induced proteins and lignin pattern changes, and redistributed the manganese, sodium, potassium, and calcium contents between the shoot and root. However, neither the redistributions nor manganese superoxide dismutase expression were affected by MnNPs but by MnSO4. This study describes how nanopriming elicits compositional changes and molecular interactions among key biomolecules and implies the role of MnNPs in plant salt stress management in order to promote sustainable agriculture.