Effects of arsenic species and phosphorus on arsenic absorption, arsenate reduction and thiol formation in excised parts of Pteris vittata L.

Characterization of Arsenate Reductase in the Extract of Roots and Fronds of Chinese Brake Fern, an Arsenic Hyperaccumulator

“…In this article, however, we give unambiguous proof that the enzymatic reduction of arsenate in Chinese brake fern took place mainly in roots. The observed high levels of arsenite in the fronds and pinnae in the study of Tu et al (2003) might have been caused by nonenzymatic reduction of arsenate by GSH, which is present in all plant cells at concentrations between 1 and 10 mM (Alscher, 1989). The lower ratios of arsenite found in roots by those authors after arsenate treatment may have been caused by a fast transport after reduction into the xylem where remaining positive root pressure could have pumped the ions through the cuts back into the incubation medium.…”

“…Zhao et al (2002) hypothesized that in Chinese brake fern arsenate is likely to be reduced to arsenite in roots, because there was almost no competition between As and phosphate during the transport from roots to fronds. Previously, Tu et al (2003) conducted experiments with excised roots and fronds of Chinese brake fern that were incubated in solution containing arsenate and observed that the ratios of arsenate conversion to arsenite were 3-to 4-fold higher in shoots compared to roots. This observation led these authors to draw the conclusion that the reduction of arsenate in Chinese brake fern would take place mainly in shoots.…”

Anthocyanins, thiols, and antioxidant scavenging enzymes are involved in Lemna gibba tolerance to arsenic

“…In fact, the main strategy for As detoxification in plant cells is based on chelation by phytochelatins or other nonprotein thiols and the subsequent compartmentalization of the As-phytochelatin complex (Mishra et al 2008). Complexed forms of As have lower toxicity than free forms (Tu et al 2004).…”

Arsenic: behavior in the environment, plant uptake mechanisms and human health risks

“…Reduction in As uptake can be related to changes in the transport mechanisms of phosphate (Tu et al, 2004). When the plant necessity for phosphorus is satisfied, it reduces the uptake of both P and As (Shaw, 1989).…”

“…Hyperaccumulator and tolerant species preferentially absorb As in its dominant form in aerobic soils -arsenate (AsV) (Tu et al, 2004). Because of its similarity to phosphate (PO 4 3-), arsenate is absorbed by the plasmalemma of roots; while arsenite (AsIII) occurs passively via aquaglyceroporins, or channels that allow water movement and neutral solutes in the roots (Wang et al, 2002).…”