Influence of Se concentrations and species in hydroponic cultures on Se uptake, translocation and assimilation in non-accumulator ryegrass

The success of biofortification and phytoremediation practices, addressing Se deficiency and Se pollution issues, hinges crucially on the fate of selenium in the plant media in response to uptake, translocation and assimilation processes. We investigate the fate of selenium in root and shoot compart...

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Published in:Plant physiology and biochemistry 2016-11, Vol.108, p.372-380
Main Authors: Versini, Antoine, Di Tullo, Pamela, Aubry, Emmanuel, Bueno, Maïté, Thiry, Yves, Pannier, Florence, Castrec-Rouelle, Maryse
Format: Article
Language:English
Subjects:
Biological Transport
Chemical Sciences
Hydroponics - methods
Lolium - drug effects
Lolium - metabolism
Selenic Acid - pharmacokinetics
Selenious Acid - pharmacokinetics
Selenium - metabolism
Selenium - pharmacokinetics
Selenium - toxicity
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Summary:The success of biofortification and phytoremediation practices, addressing Se deficiency and Se pollution issues, hinges crucially on the fate of selenium in the plant media in response to uptake, translocation and assimilation processes. We investigate the fate of selenium in root and shoot compartments after 3 and 6 weeks of experiment using a total of 128 plants grown in hydroponic solution supplied with 0.2, 2, 5, 20 and 100 mg L−1 of selenium in the form of selenite, selenate and a mixture of both species. Selenate-treated plants exhibited higher root-to-shoot Se translocation and total Se uptake than selenite-treated plants. Plants took advantage of the selenate mobility and presumably of the storage capacity of leaf vacuoles to circumvent selenium toxicity within the plant. Surprisingly, 28% of selenate was found in shoots of selenite-treated plants, questioning the ability of plants to oxidize selenite into selenate. Selenomethionine and methylated organo-selenium amounted to 30% and 8% respectively in shoots and 35% and 9% in roots of the identified Se, suggesting that selenium metabolization occurred concomitantly in root and shoot plant compartments and demonstrating that non-accumulator plants can synthesize notable quantities of precursor compound for volatilization. The present study demonstrated that non-accumulator plants can develop the same strategies as hyper-accumulator plants to limit selenium toxicity. When both selenate and selenite were supplied together, plants used selenate in a storage pathway and selenite in an assimilation pathway. Plants might thereby benefit from mixed supplies of selenite and selenate by saving enzymes and energy required for selenate reduction. •Large amounts of selenate moved rapidly to shoots to circumvent Se toxicity.•Non-accumulator plants can synthesize precursor compound for volatilization.•The selenate-selenite reduction step is inhibited in mixed supplies.
ISSN:0981-9428
1873-2690
DOI:10.1016/j.plaphy.2016.07.029