Identification of CBL Genes from Foxtail Millet (Setaria italica [L.] Beauv. ) and Its Expression under Drought and Salt Stresses

CBL/CIPK signal network system plays an important role in plant stress response. In this study, we identified seven candidate CBL genes designated as SiCBL1–7 from foxtail millet (Setaria italica [L.] Beauv.) genome using bioinformatics methods. The distributions of the predicted foxtail millet CBL genes were uneven in the nine chromosomes. Sequence analysis showed that the protein sequences and structure of foxtail millet CBL genes were very conservative. All the putative CBL genes contained 7–8 introns. Most exons of those SiCBL genes contained the same base number and shared highly similar sequence identity. All foxtail millet CBL genes consisted of four EF-Hand functional domains and the distance between the EF-hand motifs was conservative. Evolutionary analysis revealed that the CBL genes existed in the early evolutionary stage of terrestrial plants and all CBL genes were divided into four subgroups. The expression patterns of those SiCBL genes under drought and salt stresses, were displayed by RT-PCR and the results showed that four SiCBL genes (SiCBL1, SiCBL2, SiCBL3, and SiCBL5) were strongly induced by drought and three SiCBL genes (SiCBL1, SiCBL3, and SiCBL7) were induced by salt stress. SiCBL3 maybe takes an important role in foxtail millet under drought because of its constitutive high level expression. Foxtail millet CBL genes reported in this study would enrich CBL members in plant kingdom and lay a foundation for studying the function and mechanisms of the CBL/CIPK network system response to stresses.