Function of a calcineurin B-like protein and its interacting protein kinase in regulating light responses in Arabidopsis

Abstract

In higher plants, calcineurin B-like (CBL) proteins and CBL-interacting protein kinases (CIPKs) represent important relays in calcium signaling. We have found that Arabidopsis cbl1/cipk1 double mutant plants exhibit hypersensitive hypocotyl responses specifically to red and blue light. Expression analyses revealed reduced expression of the light-inducible genes CHS and CAB3 in cbl1/cipk1 mutant plants. To further elucidate the pathway in which CBL1 and CIPK1 function, we focused on HYPERSENSITIVE TO RED AND BLUE 1 (HRB1) because it has been reported that hrb1 mutant plants show similar hypocotyl responses as the cbl1/cipk1 plants to both red and blue light. HRB1 has been also shown to function in cryptochrome and phytochrome signaling pathways. Interestingly, BiFC analyses showed molecular interaction between CIPK1 and HRB1 in planta. These results suggest that CBL1 and CIPK1 function in the light signaling pathway.

This work is supported by the Alexander von Humboldt Foundation and the DFG (AFGN).