Expression of the alfalfa CCCH-type zinc finger protein gene MsZFN delays flowering time in transgenic Arabidopsis thaliana

Zinc finger proteins comprise a large family and function in various developmental processes. CCCH type zinc finger protein is one kind of zinc finger protein, which function is little known. MsZFN gene encoding a CCCH type zinc finger protein was first discovered by its elevated transcript level in a salt-induced alfalfa SSH cDNA library. The previous experiment had showed that MsZFN protein was localized to the nucleus and little is known about the function of MsZFN protein and its homologous proteins in other plants including model plant, Arabidopsis thaliana. In the current study, we found that MsZFN transcript levels increased in alfalfa under continuous dark conditions and that expression was strongest in leaves and weakest in unopened flowers under light/dark conditions. Expression of MsZFN in transgenic Arabidopsis plants resulted in late flowering phenotypes under long day conditions. Yeast two-hybrid and bimolecular fluorescence complementation assays indicated that MsZFN protein can interact with itself. Transcript analyses of floral regulatory genes in MsZFN+ transgenic Arabidopsis showed enhanced expression of the flowering repressor FLOWERING LOCUS C and decreased expression of three key flowering time genes, FLOWERING LOCUS T, SUPPRESSOR OF OVEREXPRESSION OF CONSTANS and GIGANTEA. These results suggest that MsZFN primarily controls flowering time by repressing flowering genes expression under long day conditions.