Genome-Wide Identification and Characterization of Calmodulin and Calmodulin-like Genes Family in Tea Plant and Their Roles under Abiotic Stress

As an important Ca2+ sensor, calmodulin (CaM) and calmodulin-like protein (CML) play core roles in plant growth, development, and response to environmental stimuli. The CaM/CML gene family has been well characterized in various plant species, such as Arabidopsis thaliana, rice, and tomato; however, in the tea plant, the CaM/CML gene family has not been systematically and comprehensively characterized. In the present study, a total of 5 CsCaM and 60 CsCML proteins were identified from the tea plant genome, which were unevenly distributed on the 14 chromosomes of the tea plant. All the proteins contained two to four EF-hand domains. Meanwhile, an integrated analysis of physicochemical properties, sequence structure, motif identification, phylogeny, gene duplication, promoter cis-elements, and RNA-seq expression profiles in the CsCaM/CML gene family was performed. Transcriptome analysis revealed that CsCaM/CMLs were differentially expressed in different tissues of the tea plant, suggesting their potential roles in plant growth and development. The expression profiles associated with various stress treatments revealed that CsCaM/CML genes were involved in a wide range of abiotic factors, including cold and drought stress. Quantitative real-time PCR (qRT-PCR) was also used to validate the differences in expression under abiotic stress. Overall, these findings enhanced our understanding of CsCaM/CML genes and provided useful information for further research into their molecular functions in abiotic stress response, and in multiple physiological processes in the tea plant.