We describe here the Arabidopsis gene DAG1, encoding a zinc finger transcription factor of the Dof family, and show that it is involved in the control of seed germination. By a reverse genetics approach, we isolated an Arabidopsis mutant line with one T-DNA insertion in DAG1. Seeds from homozygous knockoutdag1-1 plants do not develop dormancy and germinate also in the absence of light. Segregation analysis indicates that the effect of the mutation is maternal. Accordingly, in situ mRNA hybridizations reveal expression of DAG1 in the vascular tissue of the flower and maturing fruit but not in the seed.