The Lc regulatory gene affects the formation of anthocyanin in plants. XY355 promoter, a petal-specific promoter, was obtained from the genome of rape (Brassica napus) by polymerase chain reaction (PCR). A plant expression vector, pXY60, was constructed, which contained the maize Lc regulatory gene under the control of the XY355 promoter. The vector was introduced into tobacco (Nicotiana tabacum) and petunia (Petunia hybrida) by an Agrobacterium tumefaciens-mediated method. The flower colour of some transgenic tobacco plants was changed from light red to deep red and that of some transgenic petunia plants had changed from white to light purple.