ZmCIPK8, a CBL-interacting protein kinase, regulates maize response to drought stress

Plant CBL-interacting protein kinases (CIPKs) play an important role in stress signaling transduction and enhancing plant stress tolerance. However, the functions of most CIPKs in crop plants such as maize have not been studied. Here, a novel CIPK gene, ZmCIPK8, was cloned and characterized from maize (Zea mays). The ZmCIPK8 gene has 14 introns and its encoded protein shares high homology to Arabidopsis and rice CIPKs. Yeast two-hybrid and bimolecular fluorescence complementation assay demonstrated that ZmCIPK8 interacted with ZmCBL1, ZmCBL4 and ZmCBL9. Quantitative RT-PCR analysis revealed that the mRNA accumulation of ZmCIPK8 in maize leaves and roots was promoted by drought stress. GUS gene expression driven by the ZmCIPK8 promoter was in an organ-dependent pattern and induced in Arabidopsis seedlings under drought stress. Over-expression of ZmCIPK8 in tobacco induced the expression of the NAC, CBF, and Rd29A genes and enhanced drought tolerance of transgenic tobacco seedlings. Thus, ZmCIPK8 perhaps is involved in plant response to drought and other abiotic stress through regulating stress-related genes.