Isolation and Characterization of a Calcium-Dependent Protein Kinase Gene, FvCDPK1, Responsive to Abiotic Stress in Woodland Strawberry (Fragaria vesca)

Plant calcium-dependent protein kinases (CDPKs) play vital roles in calcium signal transduction during various developmental processes and during responses to biotic and abiotic stresses. Here, we isolated and characterized a CDPK gene designated FvCDPK1 from a wild diploid strawberry accession Heilongjiang-3 (Fragaria vesca L.). The FvCDPK1 gene contains 12 exons and 11 introns, and the sequences of most exons are highly conserved in higher plants. The full-length cDNA of FvCDPK1 contains 1,825 nucleotides with an open reading frame of 1,653 bp encoding a polypeptide of 550 amino acids. The deduced FvCDPK1 protein contains the basic features of typical plant CDPKs: a catalytic kinase domain and a regulatory calmodulin-like domain containing four EF-hand calcium-binding motifs. Phylogenetic analysis confirmed that FvCDPK1 belongs to the plant CDPK family. When transiently expressed in onion epidermal cells, the FvCDPK1-GFP fusion protein was found to be localized in the nucleus. Expression analysis indicated that FvCDPK1 was expressed in fruits at different developmental and ripening stages, as well as in several tissues such as roots, runners, flowers, leaves, and meristems. Moreover, expression levels of FvCDPK1 were higher in meristems than in other vegetative tissues. Under abiotic stress conditions, however, FvCDPK1 was found to be upregulated upon abscisic acid, NaCl, cold-, or high-temperature treatments. Taken together, our data suggest that FvCDPK1 might play a role in various responses to abiotic stresses in strawberry.