Cloning And Preliminary Analysis Of PHK4 Gene Of Chinese Cabbage

Plant living cells must constantly response to many kinds of intercellular and extracellular stimulants like hormones, chemicals, light rays and microbes during the various stages in life cycle. Histidine kinases are widely existed in higher plants and are important components of two-component signal transduction systems. In cytokinin signaling of Arabidopsis, the hybrid histidine kinases act as receptors binding to the cytokinins, and are activated and autophosphorylated. Then the phosphoryl groups are releyed by AHPs to the histidine-containing response regulators, which regulate the gene expression leading to the cell responses.In this research, the full-length genomic DNA of PHK4 (pekinensis putative histidine kinase) gene was isolated from Chinese cabbage which size is 8474 bp in length, and the complete amino acid sequence was deduced. Sequence analysis showed that PHK4 is homologous to AHK4 of Arabidopsis. Blast analysis showed that the homologous rate of coding sequence was 80% and that of amino acid sequence was 91% between them. Bioinformatics analysis on the function of PHK4 predicted that the deduced amino acid sequence contained four conserved domains among histidine kinases: CHASE, HisKA, HATPase and REC. Phylogenetic analysis showed that the evolutional relationship amomg PHK4, AHK4, AHK2 and AHK3 were closer. We presume that PHK4 is a histidine kinase and function as a cytokinin receptor in the cellular signal transduction pathway in Chinese cabbage.