title: Overexpression of AtPCS1 in tobacco increases arsenic and arsenic plus cadmium accumulation and detoxification.
abstract: The heterologous expression of AtPCS1 in tobacco plants exposed to arsenic plus cadmium enhances phytochelatin levels, root As/Cd accumulation and pollutants detoxification, but does not prevent root cyto-histological damages. High phytochelatin (PC) levels may be involved in accumulation and detoxification of both cadmium (Cd) and arsenic (As) in numerous plants. Although polluted environments are frequently characterized by As and Cd coexistence, how increased PC levels affect the adaptation of the entire plant and the response of its cells/tissues to a combined contamination by As and Cd needs investigation. Consequently, we analyzed tobacco seedlings overexpressing Arabidopsis phytochelatin synthase1 gene (AtPCS1) exposed to As and/or Cd, to evaluate the levels of PCs and As/Cd, the cyto-histological modifications of the roots and the Cd/As leaf extrusion ability. When exposed to As and/or Cd the plants overexpressing AtPCS1 showed higher PC levels, As plus Cd root accumulation, and detoxification ability than the non-overexpressing plants, but a blocked Cd-extrusion from the leaf trichomes. In all genotypes, As, and Cd in particular, damaged lateral root apices, enhancing cell-vacuolization, causing thinning and stretching of endodermis initial cells. Alterations also occurred in the primary structure region of the lateral roots, i.e., cell wall lignification in the external cortex, cell hypertrophy in the inner cortex, crushing of endodermis and stele, and nuclear hypertrophy. Altogether, As and/or Cd caused damage to the lateral roots (and not to the primary one), with such damage not counteracted by AtPCS1 overexpression. The latter, however, positively affected accumulation and detoxification to both pollutants, highlighting that Cd/As accumulation and detoxification due to PCS1 activity do not reduce the cyto-histological damage.
authors.affiliation: Department of Environmental Biology, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Letizia
authors.initials: L
authors.lastname: Zanella
authors.affiliation: Department of Environmental Biology, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Fattorini
authors.affiliation: Dipartimento di Biologia e Biotecnologie Charles Darwin, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Brunetti
authors.affiliation: Dipartimento di Scienze della Terra, dell'Ambiente e della Vita, Polo Botanico Hanbury, University of Genoa, Genoa, Italy.
authors.forename: Enrica
authors.initials: E
authors.lastname: Roccotiello
authors.affiliation: Dipartimento di Scienze della Terra, dell'Ambiente e della Vita, Polo Botanico Hanbury, University of Genoa, Genoa, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Cornara
authors.affiliation: Department of Environmental Biology, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: D'Angeli
authors.affiliation: Department of Environmental Biology, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Della Rovere
authors.affiliation: Istituto di Biologia Medicina Molecolare e Nanobiotecnologie Consiglio Nazionale delle Ricerche, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Maura
authors.initials: M
authors.lastname: Cardarelli
authors.affiliation: Dipartimento di Scienze della Terra, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Barbieri
authors.affiliation: Department of Life Sciences, University of Parma, Parma, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Sanità di Toppi
authors.affiliation: Department of Life Sciences, University of Parma, Parma, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Degola
authors.affiliation: Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Lindberg
authors.affiliation: Department of Environmental Biology, "Sapienza" University of Rome, Rome, Italy.
authors.forename: Maria Maddalena
authors.initials: MM
authors.lastname: Altamura
authors.affiliation: Department of Environmental Biology, "Sapienza" University of Rome, Rome, Italy. giuseppina.falasca@uniroma1.it.
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Falasca
mesh_terms: D019881:Aminoacyltransferases / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001151:Arsenic / Q000378:metabolism* / Q000633:toxicity; D002104:Cadmium / Q000378:metabolism* / Q000633:toxicity; D018506:Gene Expression Regulation, Plant; D008658:Inactivation, Metabolic; D054811:Phytochelatins / Q000378:metabolism*; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified; D036226:Seedlings / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D014026:Nicotiana / Q000235:genetics / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; D002104:Cadmium; D054811:Phytochelatins; D019881:Aminoacyltransferases; C502365:AT5G44070 protein, Arabidopsis; D001151:Arsenic
keywords: Arsenic and cadmium; AtPCS1 overexpression; Element analysis; Leaf crystal; Nicotiana tabacum; Phytochelatin; Root damage