title: Microscopic biomineralization processes and Zn bioavailability: a synchrotron-based investigation of Pistacia lentiscus L. roots.
abstract: Plants growing on polluted soils need to control the bioavailability of pollutants to reduce their toxicity. This study aims to reveal processes occurring at the soil-root interface of Pistacia lentiscus L. growing on the highly Zn-contaminated tailings of Campo Pisano mine (SW Sardinia, Italy), in order to shed light on possible mechanisms allowing for plant adaptation. The study combines conventional X-ray diffraction (XRD) and scanning electron microscopy (SEM) with advanced synchrotron-based techniques, micro-X-ray fluorescence mapping (μ-XRF) and X-ray absorption spectroscopy (XAS). Data analysis elucidates a mechanism used by P. lentiscus L. as response to high Zn concentration in soil. In particular, P. lentiscus roots take up Al, Si and Zn from the rhizosphere minerals in order to build biomineralizations that are part of survival strategy of the species, leading to formation of a Si-Al biomineralization coating the root epidermis. XAS analysis rules out Zn binding to organic molecules and indicates that Zn coordinates Si atoms stored in root epidermis leading to the precipitation of an amorphous Zn-silicate. These findings represent a step forward in understanding biological mechanisms and the resulting behaviour of minor and trace elements during plant-soil interaction and will have significant implications for development of phytoremediation techniques.
authors.affiliation: Department of Chemical and Geological Sciences, University of Cagliari, 09127, Cagliari, Italy.
authors.forename: G
authors.initials: G
authors.lastname: De Giudici
authors.affiliation: Department of Chemical and Geological Sciences, University of Cagliari, 09127, Cagliari, Italy. dmedas@unica.it.
authors.forename: D
authors.initials: D
authors.lastname: Medas
authors.affiliation: Science Department, University Roma Tre, 00146, Rome, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Meneghini
authors.affiliation: Institute of Translational Pharmacology, UOS of Cagliari, National Research Council, Scientific and Technological Park of Sardinia POLARIS, Pula, Italy.
authors.forename: M A
authors.initials: MA
authors.lastname: Casu
authors.affiliation: Elettra-Sincrotrone Trieste, Basovizza, Trieste, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Gianoncelli
authors.affiliation: Elettra-Sincrotrone Trieste, Basovizza, Trieste, Italy.|ESRF-The European Synchrotron, 71 Avenue des Martyrs, 38000, Grenoble, France.
authors.forename: A
authors.initials: A
authors.lastname: Iadecola
authors.affiliation: CRS4-Microlab Scientific and Technological Park of Sardinia, Pula, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Podda
authors.affiliation: Department of Chemical and Geological Sciences, University of Cagliari, 09127, Cagliari, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Lattanzi
mesh_terms: D000535:Aluminum / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D001673:Biodegradation, Environmental; D007558:Italy; D008855:Microscopy, Electron, Scanning; D027927:Pistacia / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D058441:Rhizosphere; D012825:Silicon / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D014961:X-Ray Diffraction; D015032:Zinc / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism
chemical_list: D012987:Soil; D012989:Soil Pollutants; D000535:Aluminum; D015032:Zinc; D012825:Silicon
keywords: Aluminium; Metal bioavailability; Pistacia lentiscus L.; Plant biomineralization; Silicon; XAS; Zinc; μ-XRF