Plant & Animal Genomes XVI Conference Plant & Animal Genomes XVI ConferenceJanuary 12-16, 2008
Town & Country Convention Center
San Diego, CA
Day length controls flowering time in many plants. In Arabidopsis, the day-length response depends on the induction of the FLOWERING LOCUS T (FT) gene by the gene CONSTANS (CO).
In contrast to annual plants like Arabidopsis, forest trees display a perennial growth behaviour characterized by a very extended juvenile phase before flowering, and, in temperate regions of the world, an annual cycling between growth and dormancy. We have shown that the CO/FT regulatory module is functionally conserved in the aspen tree where it controls the timing of flowering. However, unexpectedly, it also controls the short-day induced growth cessation and bud set normally occuring in the fall. We show that the differences in critical daylength for growth cessation can be explained by a difference in the phase of expression of the aspen ortholog of the gene CO leading to induction of FT at the different critical daylengths. The difference in critical daylength between tree provenances is a highly adaptive trait, and this is one of very few examples where the ecogenetic mechanism to such a variation has been determined. Taken together, these data suggest that FT is not a specific regulator of flowering, but might have a more general role in regulating biological processes controlled by variations in day length. We are now investigating the ecogenetic basis for the difference in phase of CO expression and FT activation displayed by various aspen tree provenances and we will discuss these findings.