Flowers are the reproductive organs of a plant. Their formation depends on strict nuclear events that, if compromised, can leave the plant sterile. A new study by researchers at the Nara Institute of Science and Technology (NAIST) shows how two transcription factors, AGAMOUS and CRABS CLAW, bind sequentially to the gene YUC4, which is responsible for synthesizing the plant hormone auxin. The findings, which can be read in Nature Communications, provide an epigenetic explanation for proper formation of the gynoecium, the female reproductive organ of flowering plants.