Abstract EN:

[. . . ] In the first project of my thesis, a characterization of the F-box protein FBLI 7 from Arabidopsis thaliana is described. We found that SCFFBLI 7 plays an essential role in the progression of pollen mitosis II (PMII) of male gametogenesis. A null mutation of Fbll 7 generates a single-sperm pollen grain instead of a normal two-sperm pollen grain. The jbll 7 single sperm cell preferentially fertilizes the egg cell and causing seed abortion due to underdeveloped endosperm. A mutation in FIE gene that enhances the endosperm proliferation has been shown to rescue this abortion. The essential role of FBLI 7 in maintaining the CDK activity is shown by a genetic interaction between FBLJ 7 and a CDK inhibitor KRP6, where krp6 rescues partially the jbll 7 pollen phenotype. The second project is aimed to set up a future understanding about the post-translational regulation CDK inhibitor KRP2. Among the seven Arabidopsis KRPs, KRP2 has been one of the most studied. Taking advantage of its obvious leaf serration phenotype in the KRP2 over expression background, a genetic screen is designed to find nove! regulators that regulate KRP2 stability.