Fecha de publicación: -- Fuente: WIPO "tomato" The present invention belongs to the field of genetic engineering. Specifically, the present invention relates to a system for modifying or editing a target nucleotide base, a tool and a method, and more specifically, relates to an optimized QBE base editing system and the use thereof. The base editing system has high gene editing tool efficiency, high product purity, low Indel frequency, low off-target frequency and rich gene editing windows, and therefore has important value for expanding the application scenarios of base editing technology in the fields of life science basic research, agriculture, biomedicine and the like.