Does transpiration in hyperaccumulator Pteris vittata mediate asenic translocation from the roots to fronds via xylem?
By Yong-He Han
Since the first arsenic (As) hyperaccumulator Pteris vittata was discovered by Ma et al.(2001), we have clarified somewhat in As detoxification in this fern. It is believed that P. vittata, as a “model fern” for As study, may take up arsenate (AsV) and arsenite (AsIII) via phosphate transporters (PHTs) and aquaglyceroporins (AQGPs) respectively similar to Oryza sativa and Arabidopsis thaliana. Although Indriolo et al.(2010) reported that AsIII transporter PVACR3 mediates AsIII sequestration in the vacuoles of P. vittata fronds, result from Chen et al.(2013) showed different alternative that AsIII is likely to be pumped into apoplasts. One interesting question is that how P. vittata translocates AsIII from the roots to fronds, resulting in up to 2.3% As in P. vittata fronds.
Based on the fact that As promotes P. vittata growth even though hundreds of ppm As is amended, without adverse effects, and pinnae accumulates a high content of As, I think whether As translocation in P. vittata is mediated by transpiration via xylem. When P. vittata was exposed to As, it grew better than that of the condition without As amendation, and it tolerated to drought condition. We thus should answer the potential roles of transpiration in arsenic translocation in P. vittata.