A CBL-interacting protein kinase TaCIPK27 confers drought tolerance and exogenous ABA sensitivity in transgenic Arabidopsis

Drought is one of the major environmental stresses to plants. The calcium sensor, calcineurin B-like (CBL) proteins, and their interacting protein kinases (CIPK) play important roles in responding to abiotic stresses. In this study, we functionally characterized a CIPK gene from Triticum aestivum designated TaCIPK27. The transcriptional levels of TaCIPK27 were increased both in roots and leaves after treatment with polyethylene glycol 8000, abscisic acid and H2O2. Besides, TaCIPK27 interacted with AtCBL1, AtCBL3, AtCBL4, AtCBL5 and AtCBL9 in yeast two-hybrid assays. Ectopic overexpression of TaCIPK27 positively regulates drought tolerance in transgenic Arabidopsis compared with controls, which was demonstrated by seed germination and survival rates experiments, as well as the detection of physiological indices including ion leakage, malonic dialdehyde and H2O2 contents and antioxidant enzyme activities under normal and drought conditions. Moreover, higher concentration of endogenous abscisic acid was detected under drought in TaCIPK27 transgenic plants. In addition, TaCIPK27 transgenic plants were more sensitive to exogenous abscisic acid treatment at seed germination and seedling stage. The expression levels of somedrought stress and abscisic acid related genes were up-regulated in TaCIPK27 transgenic plants. The results suggest that TaCIPK27 functions as a positive regulator under drought partly in an ABA-dependent pathway.