Expression of the alfalfa FRIGIDA-like gene, MsFRI-L delays flowering time in transgenic Arabidopsis thaliana.

In Arabidopsis, allelic variation at the FRIGIDA (FRI) locus is a major determinant of natural variation in flowering time. We have identified a FRIGIDA like protein gene, MsFRI-L, with unknown function from Medicago sativa L. Expression of MsFRI-L was increased in wild alfalfa under continuous cold conditions and the gene was expressed in all tissues including roots, stems, leaves and flowers, and weakest in flowers under light/dark conditions. Expression of MsFRI-L in transgenic Arabidopsis plants resulted in late flowering phenotypes under long day conditions or treated with vernalization. Subcellular analysis showed that MsFRI-L was localized in the nucleus. Transcript profiling of floral regulatory genes in MsFRI-L transgenic Arabidopsis showed enhanced expression of the flowering repressor FLOWERING LOCUS C and decreased expression of one key flowering time genes FLOWERING LOCUS T. These results suggest that MsFRI-L delays flowering time by regulating flowering genes expression under long day conditions.