Response regulators are part of a two-component regulatory system. The type-A Arabidopsis response regulators act as negative regulators. To understand the function of type-A response regulators in the model monocot plant, rice (Japonica cultivar-group: Zhonghua11), we overexpressed two type-A OsRR genes, OsRR3 and OsRR5 (pACT1:OsRR3 and pACT1:OsRR5). We hoped to gain insight into their molecular function in cytokinin-signaling pathways.
Cytokinins play many vital roles in plant development and physiology. In plants, cytokinin signals are sensed and transduced by the two-component signal system. This signaling cascade is typically composed of three proteins: a sensory histidine kinase, a histidine phosphotransfer protein, and a response regulator. Through a comprehensive genome-wide analysis of the maize (Zea mays) genome, 48 genes were identified, including 11 ZmHKs, 9 ZmHPs, and 28 ZmRRs (21 A-type ZmRRs and 7 B-type ZmRRs).