THE IMPACT OF Cs-SeNPs ON Raphanus sativus AND Brassica juncea. BIOTRANSFORMATION AND EFFECTS ON METABOLISM

GUSTAVO MORENO-MARTIN; MARIA EUGENIA LEÓN-GONZÁLEZ; FERNANDO GABRIEL MARTÍNEZ; YOLANDA MADRID-ALBARRÁN; JON SANZ-LANDALUZE

Zaragoza

Congreso; IX International Congress on Analytical Nanoscience and Nanotechnology (IX NyNA); 2019

Selenium is an essential micronutrient for human beings and animals1. In several areas of the world such as in southern and eastern European countries Se intake is below the recommended dietary allowance (RDA), 55 μg/day. Traditionally, the most used strategy to improve selenium status in the population is through soil biofortification or foliar application of Selenate-enriched fertilizers2. In the last years, nanoparticles of physiologically important metals/metalloids are being evaluated to improve fertilizer formulations for increased uptake in plant cells and by minimizing nutrient loss. It has been reported that nano-fertilizers can improve crop productivity by enhancing the rate of seed germination, seedling growth, photosynthetic activity, nitrogen metabolism, and carbohydrate and protein synthesis3. However, the knowledge on their uptake, translocation, and fate in plants as well as their effect on plant physiology and metabolism is still scarce.In this work the biotransformation of selenium nanoparticles (SeNPs) in plants and their effect on the metabolism of essential nutrients have been evaluated. For this purpose, two plant species Raphanus sativus and Brassica juncea were hydroponically grown in presence of in house-synthesized SeNPs coated with chitosan (Cs-SeNPs) at 5 mg Se L-1 concentration level. Before performing the experiments, Cs-SeNPs were fully characterized by TEM in aqueous, perlite and 0.1 strength Hoagland?s nutrient solution with the aim of evaluating the effect of hydroponic medium composition on the size, shape and state of aggregation of these NPs. After growing, the plants were harvested and divided into root and aerial part to determine selenium accumulation, selenium species distribution and the effect of the presence of Se on micronutrients uptake such as Fe, Cu, Zn and Mo. ICP-MS measurements of the acid digest extracts provided a total content of selenium in the root and the aerial part of both plants of about 50 ± 5 and 30 ± 2 μg Se/g, respectively. In order to evaluate the biotransformation of Cs-SeNPs in their interaction with plants, selenium compounds were subsequently extracted by using protease (90% extraction efficiency) and further analyzed by HPLC-ICP-MS using an anion exchange PRP-X100 and EVO C18 columns. The method enabled the identification of two Se-containing peaks (MeSeCys, SeMet, the first in the highest concentration) by matching the retention time of the recorded signals to the commercial standards and with column recovery values of 70%. The identity of Se-metabolites was further confirmed by HPLC-ESI-MS/MS which through transitions and relative abundance also enabled the identification of ɣ-glutamyl-MeSeCys. Finally, the effect of Cs-SeNPs on Fe, Cu, Zn and Mo uptake by plant species was evaluated by Principal Component Analysis (PCA)