The CBL-interacting protein kinases’ (CIPKs) gene family plays an important role in plants under salt stress. In this study, a total of 31 PtrCIPK genes were identified in poplar. CIPKs’ gene family was divided into two categories, few intron classes and multi-intron classes. They all have the core components of the kinase domain and regulatory domain unique to the CIPK gene family and share most of the same motifs. PtrCIPKs have 17 fragment repeat events and have high homology with Arabidopsis thaliana and Betula platyphylla, and partial homology with Zea mays. Prediction of cis-acting elements found that the PtrCIPK gene family has the most elements in terms of stress. Under NaCl stress, all members of poplar CIPKs’ gene family were significantly expressed. There were fourteen up-regulated genes and four down-regulated genes. Candidate gene expression was significantly higher in the phloem than in other tissues. In this study, characterization of CBL-interacting protein kinases’ gene family and expression pattern reveal their important roles in response to salt stress in poplar.

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