Calcium-dependent protein kinases (CDPKs) sense the calcium concentration changes in plant cells and play important roles in signaling pathways for disease resistance and various stress responses as indicated by emerging evidences. Among the 20 wheat CDPK genes studied, 10 were found to respond to drought, salinity and ABA treatments. Consistent with previous observations, one CDPK gene was shown to respond to multiple abiotic stresses in wheat suggesting that CDPKs could be converging points for multiple signaling pathways. Among the 12 wheat CDPK genes that were responsive to Blumeria graminis tritici (Bgt) infection or the treatment of hydrogen peroxide (H(2)O(2)), eight also responded to abiotic stresses, suggesting a cross-talk between biotic and abiotic stress signaling pathways. Phylogenetic analysis indicated that some of these genes were closely related to CDPKs from other species, whose functions have been partially studied, suggesting similar functions wheat CDPK genes. Combining the up-to-date knowledge of CDPK functions and our observations, a model was developed to project the possible roles of wheat CDPK genes in the signaling of biotic and abiotic stress responses.
Keywords: CDPK; calcium; disease resistance; kinase; signal transduction; stress response; wheat.