Identification Of A Late Flowering Locus In Arabidopsis

The transition from vegetative to reproductive growth is the major development switch in plant life cycle.The time of flower initiation is critical for plants reproductive success.Molecular genetic studies on Arabidopsis thaliana revealed four main flowering controlling pathways: photoperiod,vernalization,autonomous,and gibberellins pathway.Although extensive works have been done,the knowledge of flowering time control is also limited.We isolated a late-flowering Arabidopsis mutant,named flx (flowering locus x).In this thesis,the genetic background of the mutant was "cleaned up" by backcrossing to wild type.The photoperiod and GA effect on flowering time of flx was studied,and FY gene was cloned and sequenced.In order to remove extraneous mutations,the flx plants were backcross to their wild-type parents.Each time flx is crossed to wild-type,one half of the mutant genome is replaced with wild-type genes.Subsequent analysis of the F₂ population allows the plants that are homozygous for the recessive mutation of interest to be recovered.The homozygous flx plants were selected for subsequent study.The effect of the photoperiod and GA on flx flowering time was studied. The mutant retains photoperiod responses,and the late flowering phenotype was significantly restored by GA.These findings suggested that flx did not involve photoperiod and gibberellins pathway.In addition,mapping results showed the flx is near the FY gene.We cloned and sequenced the FY gene in flx mutant.Sequencing results showed that FY gene was not mutated in flx,therefore flx appeared to identify a novel locus.