An object of the present inventioin is to search for a gene having a novel function that can cause an increase or decrease in material productivity, and particularly, fat and oil content. In the present invention, a chimeric protein obtained by fusing a transcription factor consisting of a protein comprising an amino acid sequence shown in any of the even-numbered SEQ ID NOS: 1 to 158 and a functional peptide capable of converting an arbitrary transcription factor into a transcriptional repressor is expressed in a plant.
