A method of modifying morphology in a plant by introducing into a plant at least one chimaeric gene having a promoter sequence operably associated with a nucleic acid sequence, the promoter sequence being operable to direct expression in specific cells of the plant and the nucleic acid sequence encoding at least one gene product capable of altering the metabolism of or causing death of the specific cells and/or nearby cells. In particular, the promoter sequence is operable to direct expression in lateral bud or lateral shoot and the nucleic acid encoding at least one gene product capable of disrupting the metabolism of or causing the death of the lateral bud or lateral shoot or nearby cells. Preferably the promoter sequence has the sequence shown as SEQ ID No. 1 or SEQ ID No. 7 or SEQ ID No. 4, or a part thereof capable of regulating expression of a gene, or a sequence having at least 60%, preferably at least 75%, homology to SEQ ID No. 1 or SEQ ID No. 7 and being capable of regulating expression of a gene.