Genome-modified silkworm producing chimeric silk thread

A method of producing a genome-modified silkworm that produces a chimeric fibroin protein comprising a silkworm-derived fibroin protein and a fibroin protein derived from one or a plurality of species of other silk-spinning insects, the method comprising:

• a) introducing a Left-TALEN mRNA or a Left-TALEN expression vector, a Right-TALEN mRNA or a Right-TALEN expression vector, and a donor vector into an egg of a silkworm;
• b) selecting, from the silkworm after step a) a transformant comprising a fibroin gene derived from another silk-spinning insect;
• and
• c) selecting, from the transformant(s) of step b), an individual wherein the fibroin gene of the another silk-spinning insect is inserted at a target position in the genome of the silkworm;
• wherein the Left-TALEN mRNA comprises a Left-TALE region;
• wherein the Left-TALE region encodes, in the fibroin gene of the silkworm, a Left-TAL domain and a nuclease domain downstream of the Left-TAL domain, wherein the Left-TAL domain recognizes and binds to the base sequence of the 5′-side TAL binding region at the insertion site of the fibroin gene of the another silk-spinning insect;
• wherein the Left-TALEN expression vector comprises a promoter and the Left-TALE region located under the expression control by the promoter;
• wherein the Right-TALEN mRNA comprises a Right-TALE region;
• wherein the Right-TALE region encodes, in the fibroin gene of the silkworm, a Right-TAL domain and a nuclease domain downstream of the Right-TAL domain, wherein the Right-TAL domain recognizes and binds to the base sequence of the 3′-side TAL binding region at the insertion site of the fibroin gene of the another silk-spinning insect;
• wherein the Right-TALEN expression vector comprises a promoter and the Right-TALE region located under the expression control by the promoter;
• and
• wherein the donor vector comprises a 5′-side TAL corresponding region, a 3′-side TAL corresponding region, a 5′-side homologous region, a 3′-side homologous region, and the fibroin gene of the another silk-spinning insect.