Molecular cloning and functional characterization of a novel cotton CBL-interacting protein kinase gene (GhCIPK6) reveals its involvement in multiple abiotic stress tolerance in transgenic plants

• GhCIPK6 is a novel cotton CBL-interacting protein kinase gene, exhibiting the same family signature.
• GhCIPK6 was isolated from a RNA-Seq profile of stress-induced somatic embryogenesis in cotton.
• Expression of the GhCIPK6 gene was induced by salt, drought and ABA treatments.
• GhCIPK6-overexpression plant exhibited the tolerance to salt, drought and ABA stresses.
• Overexpression of GhCIPK6 activated CBL/CIPK mediated stress response signalling pathways.

Plant CIPKs were specific Ser/Thr protein kinases, which were activated through interaction with calcineurin B-like protein (CBL) containing four EF hands for Ca2+ binding. The CBL/CIPK complexes play an important role in signal transduction in biotic and abiotic stresses, as well as developmental processes. Here a Ser/Thr protein kinase gene (defined as GhCIPK6), which was isolated from RNA-Seq profile during cotton somatic embryogenesis in our previous research was characterized. The GhCIPK6 gene contains an ORF of 1296 bp that putatively encodes a polypeptide of 431 amino acids with a predicted molecular mass of 48.46 kDa and isoelectric point of 9.12. Sequence alignment analysis confirmed that GhCIPK6 has no intron, and it was homologous to AtCIPK6. Expression analysis of the GhCIPK6 suggested that they might function in diverse tissues, including styles and anthers but not fibers. In addition, expression of the GhCIPK6 gene was induced by salt, drought and ABA treatments. Overexpression of GhCIPK6 significantly enhances the tolerance to salt, drought and ABA stresses in transgenic Arabidopsis, indicating that GhCIPK6 acts as a positive regulator in response to salt and drought stress, and is supposed to be a potential candidate gene to improve stress tolerance by genetic manipulation in cotton and other crops.