The Function Of A Calcium/Calmodulin-dependent Protein Kinase Gene TaCCaMK (Triticum Aestivum L.)

Calcium/calmodulin-dependent protein kinases (CCaMKs) play pivotal roles in arbuscular mycorrhiza (AM) and rhizobial symbioses in plants. CCaMK proteins confer similar functional domains to other calcium sensors such as calcium-dependent protein kinases (CDPKs) that are known to be involved in abiotic stress responses. The possible role of CCaMKs in perceiving calcium signals from abiotic stress is elusive. We show here the cloning and functional characterization a wheat CCaMK gene TaCCaMK, which maintained identical key functional amino acids to known CCaMKs. The exon-intron configurations were conserved between TaCCaMK and those from several other species, but intron sizes varied significantly, especially between monocots and eudicots. The expression of TaCCaMK was negatively regulated by NaCl, PEG, and ABA, suggesting that TaCCaMK may be involved in abiotic stress responses. With five predicted ABA responsive cis-elements, the TaCCaMK promoter was able to drive constitutive expression of the GUS reporter gene in transgenic Arabidopsis plants, which was repressible by ABA treatment. Arabidopsis plants over expressing TaCCaMK were less sensitive to ABA in seed germination and primary root elongation assays. Seeds of transgenic plants were also less sensitive to NaCl during germination and the seedlings were prone to chlorosis under higher NaCl concentrations when compared with the controls, possibly because of their reduced sensitivity to ABA. Taken together, our data indicates that, in addition to its possible role in AM formation, TaCCaMK is involved in signaling abiotic stresses, opening an opportunity to exploit it for agricultural application.