Molecular cloning and functional characterization of a novel CBL-interacting protein kinase NtCIPK2 in the halophyte Nitraria tangutorum

CBL-interacting protein kinases (CIPKs) mediate many plant responses to abiotic stress. However, their functions are poorly understood in halophytes. In this study, we isolated a CIPK gene, NtCIPK2, from the halophyte Nitraria tangutorum. By sequence alignment and the construction of a phylogenetic tree, we found that NtCIPK2 is similar to CIPK2 proteins from other plants, and contains conserved domains and motifs. The promoter of NtCIPK2 harbors many cis-acting elements that might be recognized and bound by transcription factors that are related to hormones and stress responses. NtCIPK2 was ubiquitously and robustly expressed in all tested organs, and was induced by salinity, drought, heat, and cold stress. The overexpression of NtCIPK2 in Escherichia coli caused better growth against high salinity, alkalinity, and osmotic conditions, dehydration, and extreme temperatures (i.e., heat and cold) compared to the control. Thus, NtCIPK2 is a candidate gene that might improve the stress tolerance of crops and herbs through genetic manipulation.