Why is silk white instead of many colors?

In nature, the colors of cocoon are white, yellow, straw, orange, pink and green. The color of silk comes from the absorption of natural pigments when silkworm eats mulberry leaves.

Japanese scientists have found that the Y gene of Silkworm has been mutated. The DNA fragment was deleted. Y gene will enable silkworm to absorb carotenoids, a yellow chemical, from mulberry leaves.

Scientists have found that these mutant silkworms produce nonfunctional carotenoid binding protein (CBP), a protein known to be absorbed by accessory pigments.

Therefore, the researchers introduced the original Y gene into mutant silkworms through genetic engineering technology, and these silkworms produced functional CBP, so they spit out yellow silk. Moreover, after many rounds of hybridization, the yellow color of silk will be more vivid.

The preliminary research results of Japanese scientists have mastered the control method of yellow silk. I believe that with the deepening of research, when people master the method of controlling multiple colors, our silk will no longer need dyeing.