Abstract: The invention provides compositions and methods enabling the provision of plants showing an altered flowering behavior, and, particularly, genetically modified plants showing an early or delayed flower formation when compared to not correspondingly modified, but otherwise similar wild-type plants, as well as a tissue-specific promoter which may be utilized in a method for producing these genetically modified plants. The invention is based on the finding that the flowering behavior of plants may be influenced by enhancing the saccharose-cleaving activity specifically in the apical meristem of the plants. In this context, an enhancement of the saccharose-cleaving activity specifically in the apoplast of the apical meristem of plants results in an early flower formation whereas an enhancement of the saccharose-cleaving activity specifically in the cytoplasm of cells of the apical meristem leads to a delayed flower formation compared with corresponding not modified wild-type plants.