During crop domestication, mutations occurred in cis-regulatory elements (CREs) were often selected. These were beneficial because they caused subtle changes on gene expressions with minimal pleiotropic effects. However, the complexity of transcriptional regulation due to redundant and modular organization of CREs hampered the exploration of better alleles to improve crop traits. In this paper, authors took a simple strategy to rapidly generate a series of variants in promoters of developmental regulators in tomato, and successfully produced the continuum of phenotypic variations. I would like to discuss potentials and limitations of this strategy to facilitate crop improvements as well as studies in other fields.