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Sulphur and biothiol metabolism determine toxicity responses and fate of mercury in Arabidopsis
Environmental and Experimental Botany ( IF 4.5 ) Pub Date : 2021-02-01 , DOI: 10.1016/j.envexpbot.2020.104302
Juan Sobrino-Plata , Ángel Barón-Sola , Cristina Ortega-Villasante , Víctor Ortega-Campayo , Cesar González-Berrocal , Carlos Conesa-Quintana , Sandra Carrasco-Gil , María Muñoz-Pinilla , Javier Abadía , Ana Álvarez-Fernández , Luis E. Hernández

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), including 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 the notion that Hg-biothiol complexes could contribute to Hg mobilisation within plants.

中文翻译:

硫和生物硫醇代谢决定拟南芥中汞的毒性反应和归宿

摘要 汞(Hg)是人类释放的最危险的污染物之一,是全球环境关注的焦点。汞会在植物中引起氧化应激和强烈的细胞损伤,这可以通过富含硫醇的肽(生物硫醇)的生物合成来减弱,包括谷胱甘肽 (GSH) 和植物螯合素 (PC)。我们分析了五种拟南芥基因型、野生型 Col-0、三种敲低 γ-谷氨酰半胱氨酸合成酶 (γECS) 突变体和敲除 PC 合酶 (PCS) 突变体的汞耐受性和物种形成。通过 HPLC-ESI-TOFMS 在根中检测到汞-PC 复合物,其丰度在 γECS 突变体中受到限制。木质部汁液中 Hg-生物硫醇复合物的分析显示 HgPC2 发生在野生型 Col-0 拟南芥中,表明 Hg 可能与富含硫醇的代谢物相关联。参与硫同化、GSH 和 PCs 合成的 20 个基因在根和芽中差异表达,这意味着复杂的调控,可能涉及独立于 GSH 细胞水平的翻译后机制。总之,本研究描述了生物硫醇代谢和足够的 GSH 水平在 Hg 耐受性中的重要性,并首次确定了木质部汁液中的 Hg-PC 复合物。这一发现支持了汞-生物硫醇复合物可能有助于植物内汞动员的观点。本研究描述了生物硫醇代谢和足够的 GSH 水平在 Hg 耐受性中的重要性,并首次确定了木质部汁液中的 Hg-PC 复合物。这一发现支持了汞-生物硫醇复合物可能有助于植物内汞动员的观点。本研究描述了生物硫醇代谢和足够的 GSH 水平在 Hg 耐受性中的重要性,并首次确定了木质部汁液中的 Hg-PC 复合物。这一发现支持了汞-生物硫醇复合物可能有助于植物内汞动员的观点。
更新日期:2021-02-01
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