Foliar application of 24-epibrassinolide improves Solanum nigrum L. tolerance to high levels of Zn without affecting its remediation potential. (April 2020)

• Record Type: Journal Article
• Authors: Sousa, Bruno; Soares, Cristiano; Oliveira, Francisca; Martins, Maria; Branco-Neves, Simão; Barbosa, Beatriz; Ataíde, Inês; Teixeira, Jorge; Azenha, Manuel; Azevedo, Ricardo Antunes; Fidalgo, Fernanda
• Is Part Of: Chemosphere. Volume 244(2020)
• Publication Date: 2020-04
• Subjects: 24-Epibrassinolide -- Heavy metals -- Oxidative stress -- Phytoremediation -- Proline; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2019.125579
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Although Solanum nigrum L. is a phytoremediator for different metals, its growth and physiology are still compromised by toxic levels of zinc (Zn). Thus, the development of eco-friendly strategies to enhance its tolerance, maintaining remediation potential is of special interest. This study evaluated the potential of 24-epibrassinolide (24-EBL) to boost S. nigrum defence against Zn towards a better growth rate and remediation potential. After 24 days of exposure, the results revealed that Zn-mediated inhibitory effects on biomass and biometry were efficiently mitigated upon application of 24-EBL, without affecting Zn accumulation. The evaluation of oxidative stress markers reported that Zn excess stimulated the accumulation of superoxide anion (O2 .- ), but reduced hydrogen peroxide (H2 O2 ) levels, while not altering lipid peroxidation (LP). This was accompanied by an up-regulation of the antioxidant system, especially proline, superoxide dismutase (SOD) and ascorbate peroxidase (APX) in both organs, and ascorbate in roots of Zn-exposed plants. Foliar application of 24-EBL, however, induced distinctive effects, lowering proline levels in both organs, as well as APX activity in shoots and SOD in roots, whilst stimulating GSH and total thiols in both organs, as well as SOD and APX activity, in shoots and in roots, respectively. Probably due to a better antioxidant efficiency, levels of O2 .- and H2 O2 in pre-treated plants remained identical to the control, while LP further decreased in shoots. Overall, our results indicate a protective effect of 24-EBL on S. nigrum response to excess Zn, contributing for a better tolerance and growth rate, without disturbing its phytoremediation potential. Highlights: Soil contamination by heavy metals is a threat towards the environment. Solanum nigrum L. exposed to zinc had reduced yield and altered redox homeostasis. The redox alterations led to the upregulation of the antioxidant system. Pre-treatment with 24-EBL reverted the negative toxic effects imposed by zinc. 24-EBL treatment did not affect S. nigrum 's phytoremediation potential.