Bioinformatics analysis of calcium-dependent protein kinase (CPK) in Aeluropus littoralis L.

Calcium-dependent protein kinase (CPK), as a member of Ser/Thr kinases superfamily, plays a vital role in responding and adapting to biotic and abiotic stresses. The halophyte plant, Aeluropus littoralis, has been considered an attractive model to improve genetic resources of crops and plant stress genomic research. In order to identify the A. littoralis CPK gene family, the whole genome sequences were used to analyze the phylogenetic relationships, exon/intron structure, protein motif/domain organization and the prediction of protein-protein interaction networks. Fourteen AlCPK genes were identified in A. littoralis that were homologous to nine Arabidopsis thaliana CPK genes. The protein domain analysis of AlCPK showed that all studied genes belong to the CPK family due to having several EF-hand (except for AlCPK29.2, which does not have an EF-hand domain) and Kinase domains. AlCPK29.2 protein had the lowest molecular weight and aliphatic index, the highest instability index and gravy among the studied proteins. Gene structure analysis showed that most of AlCPKs (69.8%) have more than seven exons. Besides, AlCPK8 protein was predicted with two N-myristoylation and two palmitoylation motifs, while CPK34.1 protein lacked N-myristoylation, and palmitoylation motif and AlCPK5.1 protein had three palmitoylation motifs. Transcriptome analysis of 34 members of the AtCPK gene family in five abiotic stresses showed that AtCPK genes had diverse expression at different treatments, which could be evidence for AtCPK tissue/ stress-specific expression. The ABF4 gene was identified as one of the components of ABA signaling in AlCPK protein-protein interactions. The findings of this research can be used to classify the roles and pathways of the stress response by studying AlCIPK gene expression under different abiotic stresses.