Interactive effect of silicon and nitric oxide effectively contracts copper toxicity in Salvia officinalis L.

Abstract

Excess copper (Cu) causes the toxic effects in plants and health hazards to humans. Therefore, in this study, the effect of sodium silicate (1 mM Si) and sodium nitroprusside (200 µM SNP as a releasing NO), was assessed on Cu tolerance in Salvia officinalis L. plants exposed to 400 µM CuSO₄. Results revealed that the combined supplementation with Si and SNP rather than the single application of these chemicals lowered Cu concentrations and translocation factor and increased Mg, Zn, and Fe concentrations in roots and shoots. Furthermore, combined treatment more efficiently decreased electrolyte leakage enhanced the activities of POD and APX in the leaves and roots, and improved relative water content and the content of Chl. a and Chl. b in leaves and consequently further increased tolerance index. Silicon supply enhanced NO content and applying Si + SNP more than the treatment of Si alone increased Si concentrations in the roots and shoots under Cu stress. Therefore, the reciprocal interaction of Si and NO might enhance Cu tolerance in plants, and the combined application of Si and SNP might be a promising strategy to decrease heavy metal accumulation in medicinal plants grown in polluted lands.

NOVELTY STATEMENT

In most studies, co-precipitation of silicon and heavy metals in medium has been suggested as a reason for reducing heavy metal uptake in plants. In this study, the impact of Si on NO generation and the role of NO signaling in regulating Cu uptake and translocation and defensive responses were assessed to clarify another mechanism of Si in inducing Cu tolerance in sage. Furthermore, the combined application of Si and SNP has been indicated as an innovative strategy to enhance Cu tolerance and decrease heavy metal accumulation in medicinal plants grown in polluted lands.

Keywords:

• Antioxidant enzymes
• cation homeostasis
• Cu accumulation
• Sage
• silicon
• SNP

Author contributions

Pariya Pirooz: performing experiments, data analysis, and writing. Rayhaneh Amooaghaie: supervision, conceptualization, designing, methodology, and writing. Somayeh Bakhtiari: atomic absorption analysis, visualization, ad vision, and reviewing. All authors also participated and agreed with the approval of the final version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The raw data of this MS are available and Excel of data can be rendered upon reasonable request.

Additional information

Funding

This study was funded by the Plant Science Department of Shahrekord University, Iran.