Genome-wide identification and expression analysis of salinity stress-related protein kinase in cotton

Salinity stress is a worldwide problem that damages crop growth and development. As a principal regulatory component in eukaryotic cells, protein kinase is key to regulating crop tolerance to salinity stress. However, it is still unclear about the responses of protein kinase to salinity stress across different upland cotton species in China. This study was conducted to evaluate the functional expression of protein kinase genes in three cotton species (Gossypium hirsutum, Gossypium raimondii, and Gossypium arboretum) under salinity stress. A total of 134 genes that encode the protein kinase were recognized in cotton species. The results indicated that 67 genes belonged to G. hirsutum, 34 genes belonged to G. arboretum, and 33 genes belonged to G. raimondii, respectively. Protein kinase genes were unequally distributed on the chromosomes of the three cotton species. Based on the syntenic analysis, 58 protein kinase genes were duplicated in G. hirsutum, G. raimondii, and G. arboretum. The results of synonymous (Ks), non-synonymous (Ka), and Ka/Ks values for orthologous genes showed that the top 10 G. hirsutum protein kinase genes were mostly expressed. Co-expression network analysis of protein kinase genes confirmed their function in improving crop tolerance to salinity stress for different cotton species. It was concluded that protein kinase genes were stress-inducible and were linked to stress-responsive miRNAs in cotton species. The findings can be used for breeding new salt-tolerant cotton varieties in China. Protein kinases upregulated the responses of cotton plants to salinity stress.A total of 134 genes that encode the protein kinase were recognized in cotton species.Most protein kinase genes made clusters on the lower part and upper part arms of chromosomes.Protein kinase subfamily genes exert a positive function in improving cotton's tolerance to salt stress.