Plant-minerals-water interactions: An investigation on Juncus acutus exposed to different Zn sources

• Published in: The Science of the total environment Vol. 870; p. 161931
• Main Authors: Medas, Daniela, Meneghini, Carlo, Pusceddu, Claudia, Carlomagno, Ilaria, Aquilanti, Giuliana, Dore, Elisabetta, Murgia, Vittorio, Podda, Francesca, Rimondi, Valentina, Vacca, Salvatore, Wanty, Richard B., De Giudici, Giovanni
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 20.04.2023
• Subjects: Biodegradation, Environmental; citrates; cysteine; environment; hydrochemistry; irrigation; Juncus acutus; Metal speciation; Metals - analysis; mineral content; Minerals - analysis; phytoremediation; plant growth; plant height; Plant Roots - metabolism; Plants - metabolism; Pollutants; Rhizosphere; Rhizosphere minerals; Soil Pollutants - analysis; Water - analysis; XANES; Zinc - analysis; Pollutants; Rhizosphere minerals; Metal speciation; XANES
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.161931

Juncus acutus has been proposed as a suitable species for the design of phytoremediation plans. This research aimed to investigate the role played by rhizosphere minerals and water composition on Zn transformations and dynamics in the rhizosphere-plant system of J. acutus exposed to different Zn sources. Rhizobox experiments were conducted using three different growing substrates (Zn from 137 to 20,400 mg/kg), and two irrigation lines (Zn 0.05 and 180 mg/l). The plant growth was affected by the substrate type, whereas the Zn content in the water did not significantly influence the plant height for a specific substrate. J. acutus accumulated Zn mainly in roots (up to 10,000 mg/kg dw); the metal supply by the water led to variable increases in the total Zn concentration in the vegetal organs, and different Zn distributions both controlled by the rhizosphere mineral composition. Different Zn complexation mechanisms were observed, mainly driven by cysteine and citrate compounds, whose amount increased linearly with Zn content in water, but differently for each of the investigated systems. Our study contributes to gain a more complete picture of the Zn pathway in the rhizosphere-plant system of J. acutus. We demonstrated that this vegetal species is not only capable of developing site-specific tolerance mechanisms, but it is also capable to differently modulate Zn transformation when Zn is additionally supplied by watering. These findings are necessary for predicting the fate of Zn during phytoremediation of sites characterized by specific mineralogical properties and subject to water chemical variations. [Display omitted] •Zn tolerance occurs by Zn complexation to citrate and cysteine.•Variation of Zn content in water lead to different uptake mechanisms.•Zn complexation by J. acutus is mainly influenced by rhizosphere mineralogy.