Arabidopsis CIPK14 positively regulates glucose response.

Calcium is a ubiquitous intracellular secondary messenger in plants. Calcineurin B-like proteins (CBLs), which contain four Ca(2+)-binding EF hand motifs, are Ca(2+) sensors and regulate a group of Ser/Thr protein kinases called CBL-interacting protein kinases (CIPKs). Although the CBL-CIPK network has been demonstrated to play crucial roles in plant development and responses to various environmental stresses in Arabidopsis, little is known about their function in glucose signaling. In the present study, we identified CIPK14 gene from Arabidopsis that play a role in glucose signaling. The subcellular localization of CIPK14 was determined using green fluorescence protein (GFP) as the reporter. Furthermore, the expression levels of CIPK14 in response to salt, drought, cold, heat, ABA, methyl viologen (MV) and glucose treatments were examined by quantitative RT-PCR and it was found to respond to multiple stimuli, suggesting that CIPK14 may be a point of convergence for several different signaling pathways. Moreover, knock-out mutation of CIPK14 rendered it more sensitive to glucose treatment. Yeast two-hybrid assay demonstrated that CIPK14 interacted with three CBLs and also with two key kinases, sucrose non-fermenting 1-related kinase (SnRK) 1.1 and SnRK1.2 implicated in glucose signaling. This is the first report to demonstrate that CIPK also plays a role in glucose signaling.
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