title: iTRAQ-based proteomic analysis reveals the mechanisms of silicon-mediated cadmium tolerance in rice (Oryza sativa) cells.
abstract: Silicon (Si) can alleviate cadmium (Cd) stress in rice (Oryza sativa) plants, however, the understanding of the molecular mechanisms at the single-cell level remains limited. To address these questions, we investigated suspension cells of rice cultured in the dark environment in the absence and presence of Si with either short- (12 h) or long-term (5 d) Cd treatments using a combination of isobaric tags for relative and absolute quantitation (iTRAQ), fluorescent staining, and inductively coupled plasma mass spectroscopy (ICP-MS). We identified 100 proteins differentially regulated by Si under the short- or long-term Cd stress. 70% of these proteins were down-regulated, suggesting that Si may improve protein use efficiency by maintaining cells in the normal physiological status. Furthermore, we showed two different mechanisms for Si-mediated Cd tolerance. Under the short-term Cd stress, the Si-modified cell walls inhibited the uptake of Cd ions into cells and consequently reduced the expressions of glycosidase, cell surface non-specific lipid-transfer proteins (nsLTPs), and several stress-related proteins. Under the long-term Cd stress, the amount of Cd in the cytoplasm in Si-accumulating (+Si) cells was decreased by compartmentation of Cd into vacuoles, thus leading to a lower expression of glutathione S-transferases (GST). These results provide protein-level insights into the Si-mediated Cd detoxification in rice single cells.
authors.affiliation: College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Ma
authors.affiliation: College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Huachun
authors.initials: H
authors.lastname: Sheng
authors.affiliation: College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Xiuli
authors.initials: X
authors.lastname: Li
authors.affiliation: College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China. Electronic address: ljwang@mail.hzau.edu.cn.
authors.forename: Lijun
authors.initials: L
authors.lastname: Wang
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects*; D002104:Cadmium / Q000633:toxicity*; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects; D005982:Glutathione Transferase / Q000378:metabolism; D007553:Isotope Labeling / Q000379:methods*; D008856:Microscopy, Fluorescence; D012275:Oryza / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D059828:Plant Cells / Q000187:drug effects / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism; D040901:Proteomics / Q000379:methods*; D012825:Silicon / Q000494:pharmacology*; D013312:Stress, Physiological / Q000187:drug effects; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D002104:Cadmium; D013482:Superoxide Dismutase; D005982:Glutathione Transferase; D012825:Silicon
keywords: Cadmium (Cd); Proteome; Rice (Oryza sativa) cells; Silicon (Si); iTRAQ