Identification and abiotic stress analysis of calmodulin-binding transcription activator/signal responsive genes in non-heading Chinese cabbage (Brassica campestris ssp. chinensis Makino)

In cells, calmodulin (CaM) is the most remarkable Ca transducer. BcCAMTA gene family members are calmodulin-binding transcription activators, which contain new type of sequence-specific DNA-binding domain (CG-1), an ankyrin repeats and tow IQ calmodulin-binding motifs. In our study, 8 calmodulin-binding transcription activator (CAMTA) genes were identified from non-heading Chinese cabbage (Brassica campestris ssp. chinensis Makino, NHCC), and named as BcCAMTA1, BcCAMTA2.1, BcCAMTA2.2, BcCAMTA3.1, BcCAMTA3.2, BcCAMTA4, BcCAMTA5 and BcCAMTA6 through BcCAMTA genes cloning and according AtCAMTAs. Compared with the classification between Arabidopsis and Chinese cabbage, BcCAMTA family was divided into six subgroups (respectively named as BcCAMTA1-6). Subcellular localization prediction showed that most of the BcCAMTAs were located in the nucleus, except BcCAMTA2.2 and BcCAMTA6 that were located in the cytosol, indicating the different function among BcCAMTAs. The evolution and phylogenetic analysis of BcCAMTAs together with their orthologs from other species showed that CAMTA transcription factor family members duplicated in evolution of species, as well as BcCAMTAs, which showed closer evolutionary relationship with Arabidopsis and Chinese cabbage. Seedlings were exposed to four abiotic stresses including cold, drought, copper ion and nitrate stress to explore the transcriptional levels of BcCAMTA genes. The result exhibited that BcCAMTAs, except for BcCAMTA2, were up-regulated under cold stress in 4 h, among which showed the positive regulation to resist cold stress of NHCC. The expression of BcCAMTA2.1 and BcCAMTA3.2 were found significantly differential expression in five development stages of NHCC, and expressed highest in flowering stage.