Identification and expression analysis revealed drought stress-responsive Calmodulin and Calmodulin-like genes in maize

Calmodulin (CaM) and Calmodulin-like (CML) genes are the primary families of Calcium (Ca2+) sensors which are found to be involved in response to various stresses. Some genes involved in Ca2+ signal transduction have been genome-wide characterized in various species. However, the detailed identification, characterization, and expression profilings of ZmCaM and ZmCML genes in maize remain poorly understood, especially in the response to drought stress. In this study, a total of 7 ZmCaMs and 46 ZmCMLs are identified in maize and unevenly located on 10 chromosomes. ZmCaM and ZmCML proteins are divided into 9 groups. Protein structures analysis shows that the EF-hand motif number of ZmCaMs/ZmCMLs ranges from 3 to 4 and 2 to 4, respectively. A large number of cis-regulatory elements are found in the promoter regions of ZmCaM and ZmCML genes. ZmCaM and ZmCML genes display highly diversified tissue-specific expression patterns. Furthermore, ZmCaM2, ZmCML3, ZmCML6, ZmCML8, ZmCML19, ZmCML24, ZmCML27, ZmCML28, ZmCML36, ZmCML39, and ZmCML40 are induced significantly under drought stress through RNA-seq data and RT-qPCR. Taken together, these results will help to understand the critical roles of ZmCaM and ZmCML genes played in drought resistance and provide valuable candidate genes that could be used to develop drought-resistant maize.