Molecular Analysis of Rice CIPKs Involved in Both Biotic and Abiotic Stress Responses

Plant calcineurin B-like (CBL) proteins have been proposed as important Ca2+ sensors and specifically interact with CBL-interacting protein kinases (CIPKs) in plant-specific calcium signaling. Here, we identified and isolated 15 CIPK genes in a japonica rice variety Nipponbare based on the predicted sequences of rice CIPK gene family. Gene structure analysis showed that these 15 genes were divided into intron-less and intron-rich groups, and OsCIPK3 and OsCIPK24 exhibited alternative splicing in their mature process. The phylogenetic analyses indicated that rice CIPKs shared an ancestor with Arabidopsis and poplar CIPKs. Analyses of gene expression showed that these OsCIPK genes were differentially induced by biotic stresses such as bacterial blight and abiotic stresses (heavy metal such as Hg2+, high salinity, cold and ABA). Interestingly, five OsCIPK genes, OsCIPK1, 2, 10, 11 and 12, were transcriptionally up-regulated after bacterial blight infection whereas four OsCIPK genes, OsCIPK2, 10, 11 and 14, were induced by all treatments, indicating that some of OsCIPK genes are involved in multiple stress response pathways in plants. Our finding suggests that CIPKs play a key role in both biotic and abiotic stress responses.