Highly efficient xylem transport of arsenite in the arsenic hyperaccumulator Pteris vittata

Abstract

Summary• The hyperaccumulator Pteris vittata translocates arsenic (As) from roots to fronds efficiently, but the form of As translocated in xylem and the main location of arsenate reduction have not been resolved.• Here, P. vittata was exposed to 5 µM arsenate or arsenite for 1-24 h, with or without 100 µM phosphate. Arsenic speciation was determined in xylem sap, roots, fronds and nutrient solutions by high-performance liquid chromatography (HPLC) linked to inductively coupled plasma mass spectrometry (ICP-MS).• The xylem sap As concentration was 18-73 times that in the nutrient solution. In both arsenate-and arsenite-treated plants, arsenite was the predominant species in the xylem sap, accounting for 93-98% of the total As. A portion of arsenate taken up by roots (30-40% of root As) was reduced to arsenite rapidly. The majority (c. 80%) of As in fronds was arsenite. Phosphate inhibited arsenate uptake, but not As translocation. More As was translocated to fronds in the arsenite-treated than in the arsenate-treated plants. There was little arsenite efflux from roots to the external solution.• Roots are the main location of arsenate reduction in P. vittata. Arsenite is highly mobile in xylem transport, possibly because of efficient xylem loading, little complexation with thiols in roots, and little efflux to the external medium.

First evidence on different transportation modes of arsenic and phosphorus in arsenic hyperaccumulator Pteris vittata

“…And, considering the much higher As concentration in the endodermis and vascular bundle in the long timescale (Fig. 5), it was deduced that As(III) may have been more easily transported from the endodermis to vascular bundle than As(V), in agreement with Su et al (2008). In rice and microorganisms, including Escherichia coli and yeast (Saccharomyces cerevisiae), it has been observed that As is transported as As(III) through a silicon transporter belonging to a subfamily of aquaporins (Ma et al, 2008;Porquet and Filella, 2007).…”

Arsenic Speciation in Phloem and Xylem Exudates of Castor Bean

“…Previous studies have shown that As(III) dominates in the xylem sap collected from a number of plant species exposed to As(V), including tomato, rice, cucumber, and the As hyperaccumulator P. vittata (Mihucz et al, 2005;Xu et al, 2007;Su et al, 2008Su et al, , 2010. In contrast, As(V) was found to be an important As species in the xylem sap collected from B. juncea, Holcus lanatus, and wheat, accounting for between 30% to 60% of the total As (Pickering et al, 2000;Su et al, 2010).…”

Espécies Arbóreas Potenciais Para a Revegetação De Rejeito Salino Contaminado Com Arsênio

“…O arsenato absorvido pela planta é reduzido a arsenito, que tem elevada afinidade com os grupos tiol de peptídeos (HUANG et al, 2008;MELENDEZ, 2006;SNELLER et al, 1999;SRIVASTAVA;MA;SANTOS, 2006;ZHAO et al, 2008). A complexação de arsenito por tióis é um importante mecanismo de desintoxicação de As, podendo diminuir a sua translocação, especialmente se os complexos forem sequestrados nos vacúolos de células radiculares (SU et al, 2008). A elevada translocação de As na quaresmeira pode ser resultado da baixa capacidade de complexação do metaloide nas células radiculares.…”