DNA sequences capable of encoding an enzyme protein functioning as a rice dihydrodipicolinate synthase (DHDPS). An example of the above DNA sequences is one having the base sequence represented by SEQ ID NO:1 in the Sequence Listing. Moreover, a DNA having the base sequence represented by SEQ ID NO:5 in the Sequence Listing and one having the base sequence represented by SEQ ID NO:7 each capable of encoding the protein with a DHDPS activity are obtained. By culturing vegetable cells having, transferred thereinto, a vector which carries a DNA fragment having such a DNA integrated into the downstream of a promoter, a transformed plant with a high lysine content can be regenerated.