Non-destructive and rapid interrogation of biochemical response of the leaves of wheat seedlings towards Al2O3 nanoparticles stress using attenuated total reflectance Fourier transform infrared spectroscopy

There has been tremendous development in the field of nanotechnology and consequently the release of nanoparticles in the environment and its interaction with the biotic components is inevitable. However, knowledge concerning nanomaterial biosafety, adverse effects, fate, and acquired biological reactivity is still at infancy and requires further scientific efforts to assess their possible nano-agricultural risks. Therefore, the present study aims to reveal the molecular alterations in the leaves of the wheat seedlings caused by direct exposure of Al2O3 NPs in non-destructive and rapid manner using attenuated total reflectance Fourier transform infrared spectroscopy. For this, the seedlings of wheat have been grown in sand matrix under controlled growth conditions and the toxicity of Al2O3 NPs has been introduced to the seedlings at different concentrations (0.2, 0.6, 1.0, 1.4, 1.8, 2.2, 2.6 and 3.0 mM). For determining the biochemical alterations, the infrared spectra of the leaves of control and Al2O3 NPs treated seedlings have been recorded in the wavenumber range 4000-400 cm(-1). The principle component analyses of the preprocessed spectra indicate significant discrimination between the spectral signatures of control and Al2O3 NPs treated seedlings. The treatment of Al2O3 NPs enhances the spectral features of cellulose, hemicelluloses, lignin and pectin in the leaves of wheat seedlings. The treatment also increases the area of mehtylene bands of lipids, carboxyl and amine groups of amino acids and protein. Enhancement is also observed in carbonyl fingerprint region. The increase in the area of these molecules indicates the physiological significance of these molecules in the modulation of Al2O3 NPs stress in the wheat seedlings. The study adds substantive spectral data base to the existing elusive knowledge of nanotoxicity especially Al2O3 NPs to the plants and provides a molecular mechanism that defines the occurrence of biochemical changes and defense strategy of plants towards Al2O3 NPs toxicity.