Identification of Two Calmodulin cDNA Genes for Camellia Oleifera Abel

Camellia oleifera Abel is a woody shrub or small tree that has been widely cultivated for its edible oil production in China. After establishing the cDNA library using matured seeds of C. oleifera ‘Yanggulao No.1’, the two full-length cDNA genes, 953 base pairs (bp) and 1024bp, were cloned and identified as the calmodulin genes. They were named CaM1 and CaM2 because of their high similarity in nucleotides in the encoding regions of CaMs between the two cDNAs and other higher plant CaM from GenBank (Prunus avium and Actinidia kolomikta). Both genes contained two opening reading frames (ORFs) of 450bp with 25 nucleotide substitutions, encoding the identical protein of 149 amino acids (predicted Mw of 16.83 kDa). The characteristic is consistent with the hypothesis theory “Multigenes possess identical amino acid sequence”. The two amino acid sequences of the putative CoCaM protein were highly homologous and conservative while comparing with those of other higher plants. The protein was comprised of 19 amino acids with pI (theoretical isoelectric point) of 4.10 and should be classified into a hydrophilic and acidic protein. It possessed the structure domains including four EF-hand domains and contained enzyme-binding sites. The putative protein had some degree of identity among its hydrophilicity, flexible regions and antigenicity, and shows the high flexibility. The Blast analysis indicated that the protein shared more than 94 % amino acid sequence identity with those of other plant CaMs. The two genes, severed as the transducer of Ca²⁺-dependent signals, were expressed during the peak of lipid biosynthesis, which may be crucial during Camellia oleifera physiological processes of the immune responses to bacterial pathogens, gene expression, protein synthesis, cell proliferation and apoptosis.