Analysis of flowering time in ecotypes of Arabidopsis thaliana

There exists variation in the timing of the initiation of flowering among different ecotypes of Arabidopsis thaliana. We have examined the basis of this variation between the early flowering Columbia (Col) ecotype and the late flowering ecotypes Coimbra (Co-4), Geneva (Ge-2), and Zurich (Zu-0). In crosses of Col to Co-4, Ge-2, and Zu-0, the late flowering trait behaved as a single dominant gene: the F1 plants were late flowering and in segregating F2 populations a 3:1 ratio of late to early flowering plants was observed. This dominant gene resides in a region of chromosome 4 that contains a gene (FRIGIDA) conferring late flowering in certain other Arabidopsis ecotypes. Allelism tests indicate that the same gene is responsible for late flowering in Co-4, Ge-2, Zu-0, and the San Feliu (Sf-2) ecotype. These and previous results indicate that FRIGIDA accounts for much of the later flowering observed in various ecotypes of Arabidopsis.