Assessment of the major biochemical and physiological mechanisms underlying green-synthesised selenium nanoparticles-mediated alleviation of lanthanum toxicity in mung bean (Vigna radiata L.).

The entry of various nanoparticles into environmental compartments and their eventual presence in plant-based foods and humans is inevitable. This study focussed to elucidate the major mechanisms underlying green-synthesised selenium nanoparticles (SeNPs)-mediated control of lanthanum (La) impacts in 30-day-old mung bean (Vigna radiata L.). The foliar application of 0.6 mg/L SeNPs more prominently improved stomatal behaviour, carbohydrate metabolism, growth and photosynthetic characteristics under the absence and presence of 1.5 mM La. Key indicators of oxidative stress and antioxidant metabolism were measured. The leaves from V. radiata receiving SeNPs exhibited increased antioxidant system that helped in inhibiting the La-toxicity by reducing the content of hydrogen peroxide (HO) by 58.9 % and thiobarbituric acid reactive substances (TBARS) by 52.0 % in comparison with La-stressed plants. The application of SeNPs promoted overall growth and photosynthetic functions by increasing chlorophyll content by 17.6 %, fresh weight and dry weight by 23.9 % and 25.0 %, respectively, under La stress compared to control. Additionally, the study examined the cellular levels of soluble sugars and starch, and also correlated indicators of antioxidant metabolism with the modulation of key Calvin cycle enzymes. The chloroplast of La-stressed V. radiata had disorganized thylakoids, which were transformed to well-developed thylakoids and stacked grana after foliar application of 0.6 mg/L SeNPs. Overall, these findings highlight SeNPs as a potential tool for the alleviation of La stress in plants, and also offer a favourable solution for environmental remediation and sustainable agriculture under La stress.