Abstract
In 2000, plant specific transcriptional repressors were first isolated, and next year, the repression domain named EAR-motif, was identified. Using the EAR-motif, the CRES-T system, which is useful tool to induce the knock out phenotype of each transcription factors, was developed. By contrast, biological functions of transcriptional repressors have not been fully analyzed. We present here a functional role of WUSCHEL (WUS) as a representative of transcriptional repressors.
WUS is known as a regulator of stem cell populations in shoot meristems. All activities of WUS, including maintenance of meristems and induction of AG, were eliminated when the WUS-box was mutated (WUSm1), indicating that the WUS-box is essential for WUS function. The fusion of exogenous repression domain (SRDX) complemented the defective activity regarding the induction of stem cell identity in WUSm1. By contrast, fusion of an exogenous activation domain (VP16) to WUSm1 induced flowers similar to those induced by the ectopic expression of AG. These results demonstrate that WUS is a bifunctional transcription factor, which acts mainly as a repressor and as an activator in the case of induction of AG.
