title: Microscopic processes ruling the bioavailability of Zn to roots of Euphorbia pithyusa L. pioneer plant.
abstract: Euphorbia pithyusa L. was used in a plant growth-promoting assisted field trial experiment. To unravel the microscopic processes at the interface, thin slices of E. pithyusa roots were investigated by micro-X-ray fluorescence mapping. Roots and rhizosphere materials were examined by X-ray absorption spectroscopy at the Zn K-edge, X-ray diffraction, and scanning electron microscopy. Results indicate some features common to all the investigated samples. (i) In the rhizosphere of E. pithyusa, Zn was found to exist in different phases. (ii) Si and Al are mainly concentrated in a rim at the epidermis of the roots. (iii) Zn is mostly stored in root epidermis and does not appear to be coordinated to organic molecules but mainly occurs in mineral phases such as Zn silicates. We interpreted that roots of E. pithyusa significantly promote mineral evolution in the rhizosphere. Concomitantly, the plant uses Si and Al extracted by soil minerals to build a biomineralization rim, which can capture Zn. This Zn silicate biomineralization has relevant implications for phytoremediation techniques and for further biotechnology development, which can be better designed and developed after specific knowledge of molecular processes ruling mineral evolution and biomineralization processes has been gained.
authors.affiliation: Department of Chemical and Geological Sciences, University of Cagliari , 09127 Cagliari, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Medas
authors.forename: Giovanni
authors.initials: G
authors.lastname: De Giudici
authors.forename: Maria Antonietta
authors.initials: MA
authors.lastname: Casu
authors.forename: Elodia
authors.initials: E
authors.lastname: Musu
authors.forename: Alessandra
authors.initials: A
authors.lastname: Gianoncelli
authors.forename: Antonella
authors.initials: A
authors.lastname: Iadecola
authors.forename: Carlo
authors.initials: C
authors.lastname: Meneghini
authors.forename: Elena
authors.initials: E
authors.lastname: Tamburini
authors.forename: Anna Rosa
authors.initials: AR
authors.lastname: Sprocati
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Turnau
authors.forename: Pierfranco
authors.initials: P
authors.lastname: Lattanzi
mesh_terms: D001682:Biological Availability; D028481:Euphorbia / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism*; D058441:Rhizosphere; D017640:Silicates / Q000378:metabolism; D056928:X-Ray Absorption Spectroscopy; D014961:X-Ray Diffraction; D015032:Zinc / Q000378:metabolism*
chemical_list: D017640:Silicates; D015032:Zinc