Influence of sulfate supply on selenium uptake dynamics and expression of sulfate/selenate transporters in selenium hyperaccumulator and nonhyperaccumulator Brassicaceae

Stanleya pinnata not only hyperaccumulates selenium (Se) to 0.5% of its dry weight, but also exhibits higher tissue Se-to-sulfur (S) ratios than other species and its surroundings. To investigate the mechanisms underlying this Se enrichment, we compared S. pinnata with the nonhyperaccumulators S. el...

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Bibliographic Details
Published in:The New phytologist 2018-01, Vol.217 (1), p.194-205
Main Authors: El Mehdawi, Ali F., Jiang, Ying, Guignardi, Zack S., Esmat, Ahmad, Pilon, Marinus, Pilon‐Smits, Elizabeth A. H., Schiavon, Michela
Format: Article
Language:English
Subjects:
Brassica
Brassica juncea
competition
DNA
Dry weight
Dynamics
hyperaccumulation
Nucleotide sequence
PCR
Pretreatment
Ratios
Reverse transcription
selenate
Selenium
Specificity
Stanleya elata
Stanleya pinnata
substrate specificity
sulfate
Sulfates
Sulfur
Sulphur
Tissue
Transcription
Translocation
Uptake
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Summary:Stanleya pinnata not only hyperaccumulates selenium (Se) to 0.5% of its dry weight, but also exhibits higher tissue Se-to-sulfur (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 long-(9 d) and short-term (1 h) assays, using different concentrations of selenate and competitor sulfate. Different sulfate pre-treatments (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 high-S pretreatment. The selenate uptake rate for S. pinnata (1 h) was three- to four-fold higher than for nonhyperaccumulators, and not significantly affected by 100-fold excess sulfate, which reduced selenate uptake by 100% in S. elata and 40% in B. juncea. Real-time 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 sulfate-independent. Underlying mechanisms likely include overexpression of SULTR1;2 and SULTR2;1, which may additionally have evolved enhanced specificity for selenate over sulfate.
ISSN:0028-646X
1469-8137
DOI:10.1111/nph.14838