Molecular Cloning and Expression of a cDNA Encoding a Hybrid Histidine Kinase Receptor in Tropical Periwinkle Catharanthus roseus

Abstract Signalling pathways involving histidine kinase receptors (HKRs) are widely used by prokaryotes and fungi to regulate a large palette of biological processes. In plants, HKRs are known to be implicated in cytokinin, ethylene, and osmosensing transduction pathways. In this work, a full length cDNA named CRCIK was isolated from the tropical species CATHARANTHUS ROSEUS (L.) G. Don. It encodes a 1205 amino acid protein that belongs to the hybrid HKR family. The deduced amino acid sequence shows the highest homology with AtHK1, an osmosensing HKR in ARABIDOPSIS THALIANA. In return, CrCIK protein shares very low identity with the other 10 ARABIDOPSIS HKRs. Southern blot analysis indicates that the CRCIK corresponding gene is either present in multiple copies or has very close homologues in the genome of the tropical periwinkle. The gene is widely expressed in the plant. In C. ROSEUS C20D cell suspension, it is slightly induced after exposure to low temperature, pointing to a putative role in cold-shock signal transduction.