3 research outputs found
Influence of sulfate supply on selenium uptake dynamics and expression of sulfate/selenate transporters in selenium hyperaccumulator and nonhyperaccumulator Brassicaceae
Summary
Stanleya pinnata not only hyperaccumulates selenium (Se) to 0.5% of its dry weight, but also exhibits higher tissue Seātoāsulfur (S) ratios than other species and its surroundings.
To investigate the mechanisms underlying this Se enrichment, we compared S. pinnata with the nonhyperaccumulators S. elata and Brassica juncea for selenate uptake in longā (9 d) and shortāterm (1 h) assays, using different concentrations of selenate and competitor sulfate. Different sulfate preātreatments (0, 0.5, 5 mM, 3 d) were also tested for effects on selenate uptake and sulfate transporters' expression.
Relative to nonhyperaccumulators, S. pinnata showed higher rates of root and shoot Se accumulation and less competitive inhibition by sulfate or by highāS pretreatment. The selenate uptake rate for S. pinnata (1 h) was threeā to fourāfold higher than for nonhyperaccumulators, and not significantly affected by 100āfold excess sulfate, which reduced selenate uptake by 100% in S. elata and 40% in B. juncea. Realātime reverse transcription PCR indicated constitutive upregulation in S. pinnata of sulfate transporters SULTR1;2 (root influx) and SULTR2;1 (translocation), but reduced SULTR1;1 expression (root influx).
In S. pinnata, selenate uptake and translocation rates are constitutively elevated and relatively sulfateāindependent. Underlying mechanisms likely include overexpression of SULTR1;2 and SULTR2;1, which may additionally have evolved enhanced specificity for selenate over sulfate
Influence of sulfate supply on selenium uptake dynamics and expression of sulfate/selenate transporters in selenium hyperaccumulator and nonhyperaccumulator Brassicaceae
Summary
Stanleya pinnata not only hyperaccumulates selenium (Se) to 0.5% of its dry weight, but also exhibits higher tissue Seātoāsulfur (S) ratios than other species and its surroundings.
To investigate the mechanisms underlying this Se enrichment, we compared S. pinnata with the nonhyperaccumulators S. elata and Brassica juncea for selenate uptake in longā (9 d) and shortāterm (1 h) assays, using different concentrations of selenate and competitor sulfate. Different sulfate preātreatments (0, 0.5, 5 mM, 3 d) were also tested for effects on selenate uptake and sulfate transporters' expression.
Relative to nonhyperaccumulators, S. pinnata showed higher rates of root and shoot Se accumulation and less competitive inhibition by sulfate or by highāS pretreatment. The selenate uptake rate for S. pinnata (1 h) was threeā to fourāfold higher than for nonhyperaccumulators, and not significantly affected by 100āfold excess sulfate, which reduced selenate uptake by 100% in S. elata and 40% in B. juncea. Realātime reverse transcription PCR indicated constitutive upregulation in S. pinnata of sulfate transporters SULTR1;2 (root influx) and SULTR2;1 (translocation), but reduced SULTR1;1 expression (root influx).
In S. pinnata, selenate uptake and translocation rates are constitutively elevated and relatively sulfateāindependent. Underlying mechanisms likely include overexpression of SULTR1;2 and SULTR2;1, which may additionally have evolved enhanced specificity for selenate over sulfate