Molecular cloning and characterization of BcCSP1, a Pak-choi (Brassica rapa ssp. chinensis) cold shock protein gene highly co-expressed under ABA and cold stimulation

Cold shock proteins (CSPs) are a kind of evolutionarily conserved nucleic acid-binding protein widely distributed from prokaryotes to eukaryotes. In this study, BcCSP1, a novel CSP, was isolated from a Pak-choi stress-induced cDNA library by the rapid amplification of cDNA end method. This gene had an open-reading frame (ORF) of 822 base pairs encoding 273 amino acids. BcCSP1 contained an N-terminal CSD domain and a glycine-rich region interspersed with seven CCHC-type zinc fingers at its C terminus. Multi-alignment and phylogenetic analyses showed that BcCSP1 shared high similarity to AtCSP1 and AtCSP3. Real-time polymerase chain reaction analysis showed that BcCSP1 was induced and co-expressed under cold stress and abscisic acid treatments. In addition, a BcCSP1-YFP fusion protein was localized to the nucleus and cytoplasm. These results indicated that BcCSP1 plays an important role in responses to cold and ABA treatments in Pak-choi. This work may be useful for future functional analysis of other CSP genes in Pak-choi.