title: Identification and quantification of phytochelatins in roots of rice to long-term exposure: evidence of individual role on arsenic accumulation and translocation.
abstract: Rice has the predilection to take up arsenic in the form of methylated arsenic (o-As) and inorganic arsenic species (i-As). Plants defend themselves using i-As efflux systems and the production of phytochelatins (PCs) to complex i-As. Our study focused on the identification and quantification of phytochelatins by HPLC-ICP-MS/ESI-MS, relating them to the several variables linked to As exposure. GSH, 11 PCs, and As-PC complexes from the roots of six rice cultivars (Italica Carolina, Dom Sofid, 9524, Kitrana 508, YRL-1, and Lemont) exposed to low and high levels of i-As were compared with total, i-As, and o-As in roots, shoots, and grains. Only Dom Sofid, Kitrana 508, and 9524 were found to produce higher levels of PCs even when exposed to low levels of As. PCs were only correlated to i-As in the roots (r=0.884, P <0.001). However, significant negative correlations to As transfer factors (TF) roots-grains (r= -0.739, P <0.05) and shoots-grains (r= -0.541, P <0.05), suggested that these peptides help in trapping i-As but not o-As in the roots, reducing grains' i-As. Italica Carolina reduced i-As in grains after high exposure, where some specific PCs had a special role in this reduction. In Lemont, exposure to elevated levels of i-As did not result in higher i-As levels in the grains and there were no significant increases in PCs or thiols. Finally, the high production of PCs in Kitrana 508 and Dom Sofid in response to high As treatment did not relate to a reduction of i-As in grains, suggesting that other mechanisms such as As-PC release and transport seems to be important in determining grain As in these cultivars.
authors.affiliation: Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Bloco B, Av. dos Estados 5001, Santo André (SP), Brazil.
authors.forename: Bruno Lemos
authors.initials: BL
authors.lastname: Batista
authors.forename: Meher
authors.initials: M
authors.lastname: Nigar
authors.forename: Adrien
authors.initials: A
authors.lastname: Mestrot
authors.forename: Bruno Alves
authors.initials: BA
authors.lastname: Rocha
authors.forename: Fernando
authors.initials: F
authors.lastname: Barbosa Júnior
authors.forename: Adam H
authors.initials: AH
authors.lastname: Price
authors.forename: Andrea
authors.initials: A
authors.lastname: Raab
authors.forename: Jörg
authors.initials: J
authors.lastname: Feldmann
mesh_terms: D001151:Arsenic / Q000378:metabolism*; D001692:Biological Transport; D015415:Biomarkers / Q000378:metabolism; D053898:Biosynthetic Pathways; D002851:Chromatography, High Pressure Liquid; D002523:Edible Grain / Q000378:metabolism; D008954:Models, Biological; D012275:Oryza / Q000378:metabolism*; D054811:Phytochelatins / Q000302:isolation & purification* / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D013045:Species Specificity; D021241:Spectrometry, Mass, Electrospray Ionization; D013054:Spectrophotometry, Atomic; D013438:Sulfhydryl Compounds / Q000378:metabolism
chemical_list: D015415:Biomarkers; D013438:Sulfhydryl Compounds; D054811:Phytochelatins; D001151:Arsenic
keywords: Arsenic transfer factor; HPLC-ICP-MS/ESI-MS; arsenic uptake; phytochelatins; rice