The CBL-interacting protein kinase CaCIPK7 enhances drought resistance in pepper

As a second messenger, calcium (Ca2+) is decoded and transmitted by calcineurin B-like proteins (CBLs) and CBL-interacting protein kinases (CIPKs) to mediate drought response. In this study, we characterized the stress -induced gene CaCIPK7 from pepper (Capsicum annuum L.). CaCIPK7 silencing reduced drought tolerance and abscisic acid (ABA) sensitivity in pepper. However, CaCIPK7-overexpressing pepper and tomato presented drought-tolerant and ABA-sensitive phenotypes. CaCIPK7 overexpression decreased the accumulation of reactive oxygen species (ROS) and water loss under drought stress. The activities of ROS-scavenging enzymes and the levels of the ascorbate and glutathione cycle were elevated in CaCIPK7-overexpressing plants. CaCIPK7 expression increased the transcript levels of ABA and drought-related genes. Furthermore, CaCIPK7 interacted with CaCBL1/2/4/6/7 at the plasma membrane. CaMYB4 and CaMYB88 also induced CaCIPK7 expression by directly binding to the promoter. These results demonstrate that CaCIPK7 is involved in pepper response to drought tolerance via ROS scavenging and the ABA pathway.