CDPK1, an Arabidopsis thaliana calcium-dependent protein kinase, is involved in plant defense response

Growing evidences indicate that calcium-dependent protein kinases (CDPKs) are involved in many aspects of plant's growth, development and responses to biotic and abiotic stresses. However, the biological roles of most CDPKs remain unclear. Here we report that CDPK1 is induced by infection with both virulent and avirulent Pseudomonas syringae strains. To understand the biological function of CDPK1, we analyzed phenotypes of the T-DNA insertion line (cpk10) which did not express the CDPK1 gene. The cpk10 mutant exhibited deduced expression of the defense-related genes PR1, PR2, and AIG1 following inoculation with the avirulent pathogen Pst AvrRpt2. In addition, the CDPK1 gene was found to be expressed in guard cells and the cpk10 mutant showed alteration in stomata closure after Pst DC3000 infection. We also found that expression of CDPK1 is induced by plant hormones salicylic acid, methyl jasmonate, and abscisic acid. These results indicate that CDPK1 may be involved in plant defense response.