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Sulphur and biothiol metabolism determines toxicity responses and fate of mercury in Arabidopsis
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  • Juan Sobrino-Plata,
  • Angel Baron,
  • Cristina Ortega-Villasante,
  • Victor Ortega-Campayo,
  • Cesar González-Berrocal,
  • Carlos Conesa,
  • Sandra Carrasco-Gil,
  • María Muñoz-Pinilla,
  • Javier Abadia,
  • Ana Alvarez-Fernandez,
  • Luis E. Hernandez
Juan Sobrino-Plata
Universidad Autonoma de Madrid
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Angel Baron
Universidad Autonoma de Madrid
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Cristina Ortega-Villasante
Universidad Autonoma de Madrid
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Victor Ortega-Campayo
Universidad Autonoma de Madrid-Cantoblanco Campus
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Cesar González-Berrocal
Universidad Autonoma de Madrid
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Carlos Conesa
Universidad Autonoma de Madrid
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Sandra Carrasco-Gil
Aula Dei Research Experimental Station-CSIC
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María Muñoz-Pinilla
Aula Dei Research Experimental Station-CSIC
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Javier Abadia
Aula Dei Research Experimental Station-CSIC
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Ana Alvarez-Fernandez
Aula Dei Research Experimental Station-CSIC
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Luis E. Hernandez
Universidad Autonoma de Madrid
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Abstract

Mercury (Hg) is one of the most hazardous pollutants released by humans and is of global environmental concern. Mercury causes oxidative stress and strong cellular damages in plants, which can be attenuated by the biosynthesis of thiol-rich peptides (biothiols), which include glutathione (GSH) and phytochelatins (PCs). We analysed Hg tolerance and speciation in five Arabidopsis thaliana genotypes, the wild-type Col-0, three knockdown γ-glutamylcysteine synthetase (γECS) mutants and a knockout PC synthase (PCS) mutant. Mercury-PC complexes were detected in roots by HPLC-ESI-TOFMS, with its abundance being limited in γECS mutants. Analysis of Hg-biothiol complexes in the xylem sap revealed that HgPC2 occurs in wild-type Col-0 Arabidopsis, suggesting that Hg could be translocated associated with thiol-rich metabolites. Twenty genes involved in sulphur assimilation, GSH and PCs synthesis were differentially expressed in roots and shoots, implying a complex regulation, possibly involving post-translational mechanisms independent of GSH cellular levels. In summary, the present study describes the importance of biothiol metabolism and adequate GSH levels in Hg tolerance, and identifies for the first time Hg-PC complexes in the xylem sap. This finding supports that Hg-biothiol complexes could contribute to Hg mobilisation within plants.

Peer review status:UNDER REVIEW

30 May 2020Submitted to Plant, Cell & Environment
02 Jun 2020Assigned to Editor
02 Jun 2020Submission Checks Completed
11 Jun 2020Reviewer(s) Assigned
06 Aug 2020Review(s) Completed, Editorial Evaluation Pending