title: Response of barley plants to Fe deficiency and Cd contamination as affected by S starvation.
abstract: Both Fe deficiency and Cd exposure induce rapid changes in the S nutritional requirement of plants. The aim of this work was to characterize the strategies adopted by plants to cope with both Fe deficiency (release of phytosiderophores) and Cd contamination [production of glutathione (GSH) and phytochelatins] when grown under conditions of limited S supply. Experiments were performed in hydroponics, using barley plants grown under S sufficiency (1.2 mM sulphate) and S deficiency (0 mM sulphate), with or without Fe(III)-EDTA at 0.08 mM for 11 d and subsequently exposed to 0.05 mM Cd for 24 h or 72 h. In S-sufficient plants, Fe deficiency enhanced both root and shoot Cd concentrations and increased GSH and phytochelatin levels. In S-deficient plants, Fe starvation caused a slight increase in Cd concentration, but this change was accompanied neither by an increase in GSH nor by an accumulation of phytochelatins. Release of phytosiderophores, only detectable in Fe-deficient plants, was strongly decreased by S deficiency and further reduced after Cd treatment. In roots Cd exposure increased the expression of the high affinity sulphate transporter gene (HvST1) regardless of the S supply, and the expression of the Fe deficiency-responsive genes, HvYS1 and HvIDS2, irrespective of Fe supply. In conclusion, adequate S availability is necessary to cope with Fe deficiency and Cd toxicity in barley plants. Moreover, it appears that in Fe-deficient plants grown in the presence of Cd with limited S supply, sulphur may be preferentially employed in the pathway for biosynthesis of phytosiderophores, rather than for phytochelatin production.
authors.affiliation: DAFNE, University of Viterbo, 01100 Viterbo, Italy. sastolfi@unitus.it
authors.forename: S
authors.initials: S
authors.lastname: Astolfi
authors.forename: S
authors.initials: S
authors.lastname: Zuchi
authors.forename: G
authors.initials: G
authors.lastname: Neumann
authors.forename: S
authors.initials: S
authors.lastname: Cesco
authors.forename: L
authors.initials: L
authors.lastname: Sanità di Toppi
authors.forename: R
authors.initials: R
authors.lastname: Pinton
mesh_terms: D002104:Cadmium / Q000633:toxicity*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D001467:Hordeum / Q000187:drug effects* / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D054811:Phytochelatins / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism
chemical_list: D002104:Cadmium; D013455:Sulfur; D054811:Phytochelatins; D007501:Iron; D005978:Glutathione