Ecotoxicology https://doi.org/10.1007/s10646-020-02208-1 Mechanisms of cadmium-stress avoidance by selenium in tomato plants Leticia Rodrigues Alves 1 ● Emilaine Rocha Prado 1 ● Reginaldo de Oliveira 1 ● Elcio Ferreira Santos 2 ● Ivana Lemos de Souza 3 ● André Rodrigues dos Reis 4 ● Ricardo Antunes Azevedo 5 ● Priscila Lupino Gratão 1 Accepted: 31 March 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020 Abstract Cadmium (Cd) is probably the most damaging metal to plant species; with a long biological half-life, it can be taken up by plants, disrupting the cell homeostasis and triggering several metabolic pathways. Selenium (Se) improves plant defence systems against stressful conditions, but the biochemical antioxidant responses to Cd stress in tomato plants is poorly understood. To further address the relationship of Cd-stress responses with Se mineral uptake, Cd and Se concentration, proline content, MDA and H 2 O 2 production, and the activity of SOD, APX, CAT and GR enzymes were analyzed in Micro-Tom (MT) plants submitted to 0.5 mM Cd. The results revealed different responses according to Se combination and Cd application. For instance, roots and leaves of MT plants treated with Se exhibited an increase in dry mass and nutritional status, exhibited lower proline content and higher APX and GR activities when compared with plants with no Se application. Plants submitted to 0.5 mM Cd, irrespective of Se exposure, exhibited lower proline, MDA and H 2 O 2 content and higher SOD, CAT and GR activities. Selenium may improve tolerance against Cd, which allowed MT plants exhibited less oxidative damage to the cell, even under elevated Cd accumulation in their tissues. The results suggest that Se application is an efficient management technique to alleviate the deleterious effects of Cd-stress, enhancing the nutritional value and activity of ROS-scavenging enzymes in tomato plants. Keywords Abiotic stress ● Antioxidant metabolism ● Selenium ● Solanum lycopersicum Introduction Cadmium (Cd) is a heavy metal that is toxic to living organisms. Due to bioaccumulation and its increasing use in industry, cadmium presents an increasing hazard (Alves et al. 2016, Edelstein and Ben-Hur 2018). Plants can easily uptake this heavy metal, which triggers drastic alteration in tissues and metabolic pathways (Ma et al. 2017, Zhu et al. 2018). Even at low concentrations, Cd can modify root morphology, limiting the root-to-shoot transport of nutrients (Lux et al. 2011) and decrease nutrient uptake because Cd competes with and can replace the uptake of calcium, copper, iron, manga- nese and zinc (Rabêlo et al. 2018). Moreover, Cd provokes uncontrolled oxidation that disrupt cell balance and cause electrolyte leakage, which activates biochemical responses by favouring the production of reactive oxygen species (ROS), disrupting the plant defence systems (Alves et al. 2017). Plants are able to detoxify excessive oxidation caused by Cd by complex enzymatic and non-enzymatic mechanisms that protect plant cells against oxidative damage and restore the cell redox balance (Gratão et al. 2015). The first defence response at the cellular level involves antioxidant enzymes * Priscila Lupino Gratão pl.gratao@unesp.br 1 Universidade Estadual Paulista (UNESP), Faculdade de Ciências Agrárias e Veterinárias (FCAV), Departamento de Biologia Aplicada à Agropecuária, Jaboticabal, SP CEP 14884-900, Brazil 2 Universidade de São Paulo (USP), Centro de Energia Nuclear na Agricultura (CENA), Laboratório de Nutrição Mineral de Plantas, Piracicaba, SP CEP 13418-900, Brazil 3 Universidade Estadual Paulista (UNESP), Faculdade de Ciências Agrárias e Veterinárias (FCAV), Departamento de Fitossanidade, Jaboticabal, SP CEP 14884-900, Brazil 4 Universidade Estadual Paulista (UNESP), Faculdade de Ciências e Engenharia, Laboratório de Biologia, Tupã, SP CEP 17602-496, Brazil 5 Universidade de São Paulo (USP), Escola Superior de Agricultura Luiz de Queiroz (ESALQ), Depto. de Genética, Piracicaba, SP 13418-900, Brazil Supplementary information The online version of this article (https:// doi.org/10.1007/s10646-020-02208-1) contains supplementary material, which is available to authorized users. 1234567890();,: 1234567890();,: