The Brassica napus Calcineurin B-Like 1/CBL-interacting protein kinase 6 (CBL1/CIPK6) component is involved in the plant response to abiotic stress and ABA signalling

A CBL-interacting protein kinase (CIPK) gene, BnCIPK6, was isolated in Brassica napus. Through yeast two-hybrid screening, 27 interaction partners (including BnCBL1) of BnCIPK6 were identified in Brassica napus. Interaction of BnCIPK6 and BnCBL1 was further confirmed by BiFC (bimolecular fluorescence complementation) in plant cells. Expressions of BnCIPK6 and BnCBL1 were significantly up-regulated by salt and osmotic stresses, phosphorous starvation, and abscisic acid (ABA). Furthermore, BnCIPK6 promoter activity was intensively induced in cotyledons and roots under NaCl, mannitol, and ABA treatments. Transgenic Arabidopsis plants with over-expressing BnCIPK6, its activated form BnCIPK6M, and BnCBL1 enhanced high salinity and low phosphate tolerance, suggesting that the functional interaction of BnCBL1 and BnCIPK6 may be important for the high salinity and phosphorous deficiency signalling pathways. In addition, activation of BnCIPK6 confers Arabidopsis plants hypersensitive to ABA. On the other hand, over-expression of BnCIPK6 in Arabidopsis cipk6 mutant completely rescued the low-phosphate-sensitive and ABA-insensitive phenotypes of this mutant, further suggesting that BnCIPK6 is involved in the plant response to high-salinity, phosphorous deficiency, and ABA signalling.