Flowering

Abstract

The transition from vegetative growth to flowering in higher plants is controlled by environmental conditions and developmental regulation. The complexity of this transition is created by an intricate network of signalling pathways that monitor the developmental state of the plant as well as environmental conditions (light, temperature, and photoperiod). Arabidopsis thaliana (Brassicaceae family) is an excellent model system in which to approach this complexity. Currently four genetic pathways have been identified: the light-dependent, the autonomous, the vernalization and the gibberellin pathway, all integrated by the function of regulatory genes at the integration pathway. The integrated signal of the floral induction is transmitted to the floral meristem identity genes and floral morphogenesis is performed. The promotion of flowering, by both increasing the number of flowers and advancing time of flowering, as well as creating novelty in the flower structure, are major desirable traits in ornamental plant breeding. The possibility of using molecular techniques to transfer genes in major ornamentals has greatly increased the resources available to plant breeders. Moreover, native genes can be over expressed or suppressed. The recent explanations of the mechanisms of flowering in Arabidopsis have led new sets of genes to be available. These include genes which affect flowering and flower architecture. In a few cases these genes can change the flowering time of species unrelated to the plant from which they were isolated.