Molecular characterization of photoperiodic flowering in strawberry (Fragaria sp.)

The initiation of flowering is a critical developmental transistion for most plant species, affecting reproductive potential and evolutionary success. The timing of this event in strawberry (Fragaria sp.) is conditioned by a number of factors, including photoperiod. Sensitivity to photoperiod varies among strawberry genotypes, which are generally divided into three categories: short-day, everbearing, and day-neutral. The genetic basis for these variations is not known, but existing model plant systems such Arabidopsis thaliana and rice reveal a well-conserved network of genes and proteins governing the perception of photoperiod and the regulation of floral initiation. A number of these genes were identified and characterized in strawberry and other relatives in the family Rosaceae, and their expression in strawberry under long and short photoperiods assayed. Expression profiles suggest that while many of the critical genes governing photoperiodic flowering are conserved between strawberry and model species, their expression and relationships to one another are unlike those of any previously characterized plant species.