Abstract
In Arabidopsis thaliana, Histidine to Aspartate (His-Asp) phosphorelay is a paradigm of signaling system that is considered to be involved in response to phytohormones, including ethylene and cytokinin. In the current framework of His-Asp phosphorelay, the type-B ARR (response regulator) family members appear to act as DNA-binding transcriptional regulators. Although A. thaliana has 11 type-B ARR family members, except for ARR1 and ARR2, no biological information is available with regard to others. As the main objective of this study, we extensively characterized other 9 type-B ARRs, through constructing a series of transgenic plants carrying each promoter::GUS fusion genes. Furthermore, we constructed a set of transgenic plants, aberrantly expressing the corresponding C-terminal DNA-binding activation domain of each ARR (e.g., ARR11 and ARR14). These results with regard to properties of type-B ARRs are discussed in comparison with special reference to the cytokinin-responsive His-Asp phosphorelay signal transdution in this higher plant.
