Mapping Of A Late-flowering Locus In Arabidopsis

The transition to flowering is the most critical process during the plant life cycle. The genetic and molecular analyses of Arabidopsis thaliana have revealed four interdependent genetic pathways for flowering: photoperiod, vernalization, autonomous, and gibberellin pathway. Although many flowering time gene have been cloned by isolating and identifying early- and later-flowering mutants, our understanding of flowering time control is still limited. A late-flowering Arabidopsis mutant (refer to as flx) was isolated from EMS-mutagenized plants of the Col ecotype in our lab. In this study, F₂ population was generated, mutant F₂ individuals were genotyped for SSLP molecular markers polymorphism, and the vernalization effect on flowering time on flx was studied.For mapping the flx locus, homozygous flx plants (ecotype Columbia) were outcrossed to wild type plants (ecotype Landsberg), and the resulting F₁ plants were allowed to self-fertilize to generate F₂ population. 370 late-flowering plants in the F₂ population were selected, and mutant F₂ individuals were genotyped for SSLP molecular markers polymorphic between Col and Ler. Analysis of the relationships of the gene flx with the molecular markers showed that the flx locus is located near of the markers T24H18-25983 on chromosome 5.In addition, the effect of the vernalization on flowering time of mutant flx and wild type plants was studied. The experiment showed that the late-flowering phenotype of the mutant could be restored by 5 weeks treatment of vernalization, but the 6 weeks treatment could not further accelerate the transition. This result implies that the FLX gene is not a component of the vernalization pathways.