title: Proteomic identification of OsCYP2, a rice cyclophilin that confers salt tolerance in rice (Oryza sativa L.) seedlings when overexpressed.
abstract: BACKGROUND
  High Salinity is a major environmental stress influencing growth and development of rice. Comparative proteomic analysis of hybrid rice shoot proteins from Shanyou 10 seedlings, a salt-tolerant hybrid variety, and Liangyoupeijiu seedlings, a salt-sensitive hybrid variety, was performed to identify new components involved in salt-stress signaling.
  
  
  RESULTS
  Phenotypic analysis of one protein that was upregulated during salt-induced stress, cyclophilin 2 (OsCYP2), indicated that OsCYP2 transgenic rice seedlings had better tolerance to salt stress than did wild-type seedlings. Interestingly, wild-type seedlings exhibited a marked reduction in maximal photochemical efficiency under salt stress, whereas no such change was observed for OsCYP2-transgenic seedlings. OsCYP2-transgenic seedlings had lower levels of lipid peroxidation products and higher activities of antioxidant enzymes than wild-type seedlings. Spatiotemporal expression analysis of OsCYP2 showed that it could be induced by salt stress in both Shanyou 10 and Liangyoupeijiu seedlings, but Shanyou 10 seedlings showed higher OsCYP2 expression levels. Moreover, circadian rhythm expression of OsCYP2 in Shanyou 10 seedlings occurred earlier than in Liangyoupeijiu seedlings. Treatment with PEG, heat, or ABA induced OsCYP2 expression in Shanyou 10 seedlings but inhibited its expression in Liangyoupeijiu seedlings. Cold stress inhibited OsCYP2 expression in Shanyou 10 and Liangyoupeijiu seedlings. In addition, OsCYP2 was strongly expressed in shoots but rarely in roots in two rice hybrid varieties.
  
  
  CONCLUSIONS
  Together, these data suggest that OsCYP2 may act as a key regulator that controls ROS level by modulating activities of antioxidant enzymes at translation level. OsCYP2 expression is not only induced by salt stress, but also regulated by circadian rhythm. Moreover, OsCYP2 is also likely to act as a key component that is involved in signal pathways of other types of stresses-PEG, heat, cold, or ABA.
authors.affiliation: Plant Molecular Biology & Proteomics Lab, Institute of Biotechnology, Hangzhou Academy of Agricultural Sciences, Hangzhou 310024, PR China. ruansl1@hotmail.com
authors.forename: Song-Lin
authors.initials: SL
authors.lastname: Ruan
authors.forename: Hua-Sheng
authors.initials: HS
authors.lastname: Ma
authors.forename: Shi-Heng
authors.initials: SH
authors.lastname: Wang
authors.forename: Ya-Ping
authors.initials: YP
authors.lastname: Fu
authors.forename: Ya
authors.initials: Y
authors.lastname: Xin
authors.forename: Wen-Zhen
authors.initials: WZ
authors.lastname: Liu
authors.forename: Fang
authors.initials: F
authors.lastname: Wang
authors.forename: Jian-Xin
authors.initials: JX
authors.lastname: Tong
authors.forename: Shu-Zhen
authors.initials: SZ
authors.lastname: Wang
authors.forename: Hui-Zhe
authors.initials: HZ
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D021983:Cyclophilins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D015227:Lipid Peroxidation; D008969:Molecular Sequence Data; D012275:Oryza / Q000187:drug effects / Q000378:metabolism*; D018384:Oxidative Stress; D010641:Phenotype; D010940:Plant Proteins / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000378:metabolism; D020543:Proteome; D017382:Reactive Oxygen Species / Q000378:metabolism; D054712:Salinity; D055051:Salt-Tolerant Plants / Q000187:drug effects / Q000378:metabolism*; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological
chemical_list: D010940:Plant Proteins; D020543:Proteome; D017382:Reactive Oxygen Species; D012965:Sodium Chloride; D021983:Cyclophilins