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The behaviors of antimony (Sb) and arsenic (As) in plants are different, though they are chemical analogs. Here, we examined the Sb uptake and speciation in two As-hyperaccumulators P. vittata and P. cretica , which were exposed to 0.5 or 5 mg L-1 antimonate (SbV) or antimonite (SbIII) under hydroponics for 7 d. Both plants grew better under Sb exposure, especially for P. cretica. The biomass of P. cretica roots increased by 29–46% after exposing to SbV, possibly due to increased S. Further, the Sb content in P. vittata was 17–93% greater than P. cretica , with 2–3 times more SbIII than SbV in both plants and > 92% Sb being concentrated in the roots, showing limited translocation. Under SbV exposure, SbV was dominant in P. vittata roots at 86–94%, while SbIII was predominant in P. cretica roots at 36–95%. P. cretica 's stronger reducing ability than P. vittata may be due to arsenate reductases HAC1 and ACR2 , which were upregulated in both plants. In short, while effective in Sb accumulation, it is mostly concentrated in the roots for both plants. The differences in their accumulation and speciation may help to better understand Sb behaviors in other plants. [Display omitted] • P. vittata & P. cretica grew better under Sb exposure probably due to increased S uptake. • As-hyperaccumulator P. vittata accumulates 17–93% more Sb than P. cretica. • 36–95% SbIII was in P. cretica roots while 86–94% SbV was in P. vittata roots. • SbV was reduced to SbIII in P. cretica roots via upregulating arsenate reductases. [ABSTRACT FROM AUTHOR]

Antimony (Sb) and arsenic (As) are chemical analogs, but their behaviors in plants are different. To investigate the Sb uptake, translocation and speciation in As-hyperaccumulator P. cretica , a hydroponic experiment was conducted. In this study, P. cretica was exposed to 0.2-strength Hoagland nutrient solution, which contained 0.5 or 5 mg/L antimonite (SbIII) or antimonate (SbV). After 14 d exposure, P. cretica took up 1.4–2.8 times more SbIII than SbV. Since P. cretica was unable to translocate Sb, its roots accumulated >97% Sb with the highest at 7965 mg/kg. In both SbIII and SbV treatments, SbIII was the predominant species in P. cretica , with 90–100% and 46–100% SbIII in the roots. As the first barrier against Sb to enter plant cells, more Sb was accumulated in cell wall than cytosol or organelles. The results suggest that P. cretica may detoxify Sb by reducing SbV to SbIII and immobilizing it in root cell walls. Besides, the presence of SbIII significantly reduced the concentrations of dissolved organic C including organic acids in P. cretica root exudates. Further, increasing Sb levels promoted P accumulation in the plant, especially in the fronds, which may help P. cretica growth. The information from this study shed light on metabolic transformation of Sb in As-hyperaccumulators P. cretica , which helps to better understand Sb uptake and detoxification by plants. [Display omitted] •As-hyperaccumulator Pteris cretica accumulated >7000 mg/kg Sb in the roots. • P. cretica was 2.8 times more efficient in taking up SbIII than SbV. •Most SbV in the roots was reduced to SbIII and was associated with cell wall. •SbIII reduced root exudates but increased frond P accumulation in P. cretica. [ABSTRACT FROM AUTHOR]