Nano-Boehmite Induced Oxidative and Nitrosative Stress Responses in Vigna radiata L.

Abstract

Wide spectrum and increasing use of nano-sized aluminum oxyhydroxide\xa0(boehmite, nBhm) particles have left a risk of their environmental exposure and possible toxic impacts. However, little is known about their toxicity. Current investigation was aimed to assess the toxic impacts of nBhm on Vigna radiata L., a model plant. Seedlings of V. radiata were exposed to 0 – 12\xa0mM nBhm for ten days, and nBhm reduced the biomass production in a dose-dependent manner, with the greatest impacts under 12\xa0mM nBhm causing 16% and 4% reduction in root and shoot dry weight (DW), respectively. Higher dose of nBhm damaged the cellular membrane stability and chlorophyll contents. The levels of major reactive oxygen species including superoxide radical, hydrogen peroxide and hydroxyl radical were increased by 2.65, 2.45 and 2.50 times more in leaves and 2.31, 2.55 and 5.71 times more in roots, respectively, in plants subjected to 12\xa0mM nBhm treatment. Spectrophotometry and in-gel assays confirmed that the nBhm triggered antioxidative machinery with up-regulation of superoxide dismutase, catalase and peroxidase enzymes. Concurrent accumulation of non-enzymatic antioxidants was also recorded in the form of proline and ascorbic acid. The nBhm exposed plants showed higher nitric oxide production with 12\xa0mM nBhm treatment causing 1.91- and 1.49-fold hike in nitric oxide content of leaves and roots, respectively. Interestingly, roots and leaves behaved contrastingly in terms of nitrate reductase activity in response to the nBhm treatment. The hierarchical clustering and principal component analysis revealed the closeness of the stress-indicating attributes towards higher nBhm concentrations. Collectively, nBhm exerted negative impacts on V. radiata in a dose-dependent manner, with higher toxicity at the concentration\u2009≥\u20098\xa0mM, mediated through oxidative and nitrosative bursts.