Comparative expression analysis of Calcineurin B-like family gene CBL10A between salt-tolerant and salt-sensitive cultivars in B. oleracea.

Calcineurin B-like proteins (CBLs) are plant calcium sensors that play a critical role in the regulation of plant growth and response to stress. Many CBLs have been identified in the calcium signaling pathway in both Arabidopsis and rice. However, information about BoCBLs genes from Brassica oleracea has not been reported. In the present study, we identified 13 candidate CBL genes in the B. oleracea genome based on the conserved domain of the Calcineurin B-like family, and we carried out a phylogenetic analysis of CBLs among Arabidopsis, rice, maize, cabbage and B. oleracea. For B. oleracea, the distribution of the predicted BoCBL genes was uneven among the five chromosomes. Sequence analysis showed that the nucleotide sequences and corresponding protein structure of BoCBLs were highly conserved, i.e., all of the putative BoCBLs contained 6-8 introns, and most of the exons of those genes contained the same number of nucleotides and had high sequence identities. All BoCBLs consisted of four EF-Hand functional domains, and the distance between the EF-hand motifs was conserved. Evolutionary analysis revealed that the CBLs were classified into two subgroups. Additionally, the CBL10A gene was cloned from salt-tolerant (CB6) and salt-sensitive (CB3) cultivars using RT-PCR. The results indicated that the cloned gene had a substantial difference in length (741bp in CB3 and 829bp in CB6) between these two cultivars. The deduced CBL10A protein in CB6 had four EF-hand structural domains, which have an irreplaceable role in calcium-binding and have calcineurin A subunit binding sites, while the BoCBL10A protein in CB3 had only two EF-hand structural domains and lacked calcineurin A subunit binding sites. The expression level of the BoCBL10A gene between salt tolerance (CB6)and sensitive varieties(CB3) under salt stress was significantly different (P<0.01 and P<0.05). The expression of BoCBL10A gene was relatively higher in salt-tolerant (CB6) cultivar under salt stress, with a longer period of up-regulation expression and a shorter time responding to salt, compared with the salt-sensitive (CB3) cultivar. We speculate that these differences in the coding region of BoCBL10A may lead to the different salt responses between these two cultivars.,Copyright © 2016. Published by Elsevier B.V.