Reliable and precise techniques for targeting modification of plant genomes have been explored in plant breeding communities. Initiated in the animal genome first, now the genome editing tool using a nuclease has been reported in some plant species including Arabidopsis, Maize, Tobacco, and other model systems. When the artificial nuclease is introduced into a plant cell and breaks the genomic sites randomly, endogenously operating DNA-repair mechanisms including non-homologous end joining(NHEJ) or homologous recombination(HR) are anticipated, leading to insertion of foreign DNA or deletion of the target locus, which collectively allows changes in plant traits of interest. Traditionally custom designed for induction of double-strand DNA break(DSB) at a predetermined locus was based on zinc-finger nuclease which contains nonspecific cleavage domains with target specificities of DNA binding zinc finger domains(three to four). The binding domains containing more than 20 DNA bases with high affinity to the target gene enable recognition of the locus efficiently. From this project, we focus on a petunia chalcone synthase(CHS) as a model system. The engineered nuclease will target the CHS gene, which is expected to be modified either constitutely or transiently. The derived transformed plants will be genetically or phenotypicly screened, along with molecular confirmation analysis by using various tools. We eventually extend the tools to various crop species and target genes, which makes the brand-new breeding technique more reliable and robust.