We aim to investigate the tolerance and enrichment mechanism of cesium (Cs) in hyperaccumulation plants. In this study, Brassica juncea and Vicia faba were subjected to varying doses of Cs for 21 days to investigate the differences in bio-accumulations, subcellular distribution and chemical forms of Cs in two cultivars by differential centrifugation, and extraction of Cs in different chemical forms, respectively. The results showed that 49.87%-61.08% of the Cs were in the leaf of B. juncea, while in V. faba, 1.58%-79.29% of the Cs was in the root. The translocation factor (TF) arrived 2.79 to 3.71 in B. juncea, while it only reached 0.26 to 0.62 in V. faba. Cs subcellular distribution of the two plants was in sequence as follows: soluble fraction > cell wall >> organelles. Cs was more easily distributed to metal-sensitive fractions of V. faba. The inorganic Cs (F-ethanol), and water-soluble Cs (F-dH2O) are the main existing types of Cs in the two plants. In B. juncea, the relative content of inorganic Cs, and organic acids/CsH2PO4 (F-dH2O) were higher than that of V. faba in the stem. This suggests that Cs may induce related transporter gene expression (such as phosphate transporter, organic cation, high affinity nitrate transporter, amino acid permease, etc.) to help the transport of Cs between root to shoot.
Keywords: Accumulation; Brassica juncea; Cesium; Chemical forms; Subcellular distribution; Vicia faba.
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