Introduction of a 50 kbp DNA fragment into the plastid genome.

Plastid transformation technology has been used for the analysis and improvement of plastid metabolism. To create a transplastomic plant with a complicated and massive metabolic pathway, it is necessary to introduce a large amount of DNA into the plastid. However, to our knowledge, the largest DNA fragment introduced into a plastid genome was only 7 kbp long and consisted of just three genes. Here we report the introduction of foreign DNA of 23-50 kbp into the tobacco plastid genome with a bacterial artificial chromosome (BAC)-based plastid transformation vector. It was confirmed that the introduced DNA was passed on to the next generation. This is the first description of plastid transformation with a large amount of foreign DNA.