title: Selenium inhibits the phytotoxicity of mercury in garlic (Allium sativum).
abstract: To investigate the influence of selenium on mercury phytotoxicity, the levels of selenium and mercury were analyzed with inductively coupled plasma-mass spectrometry (ICP-MS) in garlic tissues upon exposure to different dosages of inorganic mercury (Hg(2+)) and selenite (SeO3(2-)) or selenate (SeO4(2-)). The distributions of selenium and mercury were examined with micro-synchrotron radiation X-ray fluorescence (μ-SRXRF), and the mercury speciation was investigated with micro-X-ray absorption near edge structure (μ-XANES). The results show that Se at higher exposure levels (>1mg/L of SeO3(2-) or SeO4(2-)) would significantly inhibit the absorption and transportation of Hg when Hg(2+) levels are higher than 1mg/L in culture media. SeO3(2-) and SeO4(2-) were found to be equally effective in reducing Hg accumulation in garlic. The inhibition of Hg uptake by Se correlates well with the influence of Se on Hg phytotoxicity as indicated by the growth inhibition factor. Elemental imaging using μ-SRXRF also shows that Se could inhibit the accumulation and translocation of Hg in garlic. μ-XANES analysis shows that Hg is mainly present in the forms of Hg-S bonding as Hg(GSH)2 and Hg(Met)2. Se exposure elicited decrease of Hg-S bonding in the form of Hg(GSH)2, together with Se-mediated alteration of Hg absorption, transportation and accumulation, may account for attenuated Hg phytotoxicity by Se in garlic.
authors.affiliation: CAS Key Laboratory of Nuclear Analytical Techniques, Key Lab for Biomedical Effects of Nanomaterial and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Jiating
authors.initials: J
authors.lastname: Zhao
authors.forename: Yuxi
authors.initials: Y
authors.lastname: Gao
authors.forename: Yu-Feng
authors.initials: YF
authors.lastname: Li
authors.forename: Yi
authors.initials: Y
authors.lastname: Hu
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Peng
authors.forename: Yuanxing
authors.initials: Y
authors.lastname: Dong
authors.forename: Bai
authors.initials: B
authors.lastname: Li
authors.forename: Chunying
authors.initials: C
authors.lastname: Chen
authors.forename: Zhifang
authors.initials: Z
authors.lastname: Chai
mesh_terms: D000042:Absorption; D001673:Biodegradation, Environmental; D005737:Garlic / Q000378:metabolism*; D005978:Glutathione / Q000737:chemistry; D013058:Mass Spectrometry; D008628:Mercury / Q000737:chemistry / Q000493:pharmacokinetics* / Q000633:toxicity*; D012643:Selenium / Q000737:chemistry / Q000493:pharmacokinetics*; D013052:Spectrometry, X-Ray Emission; D056928:X-Ray Absorption Spectroscopy
chemical_list: D008628:Mercury; D005978:Glutathione; D012643:Selenium
keywords: Antagonism; Garlic; Mercury; Phytotoxicity; Selenium