Shinichi Arimura and colleagues have used a TALEN tool for genome editing developed in Japan. The gene encoding a citidine deaminase (CD) is linked to the TALEN domain, and a gene encoding for delivery to the chloroplast is ligated. Using this method, single nucleotide substitutions at the target site of a chloroplast genome could be achieved in all chloroplasts with 1000 copies per cell. Furthermore, in subsequent generations, no segrigants containing foreign genes were observed. Genome modification of chloroplasts has been possible since around 1990 through introducing genes by a particle gun. However, molecular breeding that is not regulated by the Cartagena Law had not yet been realized.
Nikkei Biotech news release, July 2, 2021