Optimization of Melon Genetic Transformation and Genome Editing

Melon is the widely cultivated fruit vegetable species, and it has acquired a many kinds of fruit traits, including fruit shape, aroma, and ripening patterns during the domestication. Therefore melon provides an excellent material for studies of fruits traits, which are one of the most important issues in crop development. Melon is important in plant science, because melon served as an excellent model for investigating sex determination, ripening process, and vascular fluxes since xylem and phloem saps can be readily collected. For effective use of the attractive materials, functional genomics tools are required in melon. Therefore, for the last decade, many studies has been addressed the tools, such as expressed sequence tag (EST) collections, and omics database, genetic linkage maps, DNA markers, bacterial artificial chromosome (BAC) libraries, a mutation library, a targeted induced local lesions in genomes (TILLING) platform for mutation screening, and transformation techniques. Although the transformation is a key technique for functional genomics research, the frequency is not enough for the practical use, due to the three problems such as tetraploidy, chimera, and escapes. Therefore the research efforts have been undertaken in order to establish the efficient transformation protocol in melon. Previous study showed the liquid culture system through somatic embryogenesis overcame these problems. In this study, to establish more sophisticated method, we improved the gene transfer method, that is, Agrobacterium strains, seed quality, the selection timing of embryogenic callus in two melon varieties. We have also tried to adopt this technique to the genome editing.