The calmodulin-binding transcriptional activator transcription factor family in foxtail millet (Setaria italica L.): Molecular characterization, codon bias, and evolutionary trajectory

Abstract

Calmodulin-binding transcriptional activator (CAMTA) is a calmodulin-binding transcription factor, which plays an important role in calcium/calmodulin transduction signaling pathway. Foxtail millet (Setaria italica L.) is an economically important C4 model crop, but the genome-wide identification and molecular evolution of the CAMTA family is not yet available. In this study, seven CAMTA genes were identified from the foxtail millet genome via bioinformatics methods. They were overall similar in structure but differed, and all showed tissue expression specificity. Regarding molecular evolution, codon bias contributed to the evolution of the CAMTA family, and interestingly, base mutation was not the main factor affecting their codon bias, and may also be affected by factors such as natural selection and other factors. Multiple traces indicated that polyploidization events primarily led to the expansion of the plant CAMTA family, with overall similar but differentiated expansion histories in different species, and that Selaginella moellendorfii possesses the most paralogous genes being the most distinctive. More intriguingly, we found the opposite quantitative evolutionary history of terrestrial plants to that of the algal CAMTA family. Therefore, we firstly analyzed the molecular properties of the CAMTA transcription factor family in foxtail millet and explored its molecular evolutionary trajectory, and constructed a flow of evolutionary trajectories from monospecies transition to the plant kingdom for reference.