Chinese researchers reveal how silkworms form green cocoons

CHONGQING -- A Chinese research team from Southwest University has revealed the genetic mechanism behind the green color of some silkworm cocoons, marking a new discovery in the field of biological coloration.

The study was recently published in the journal Molecular Biology and Evolution.

Compared with wild silkworms, domestic silkworms have more colorful cocoons, with varieties including white, green, and yellow-red, providing an outstanding model for exploring phenotypic diversification and biological coloration, according to the study.

A green cocoon, produced by the deposition of flavonoids, is rarer than other colors, and features better antibacterial properties, superior oxidation resistance and greater ultraviolet protection.

However, its genetic basis had not been fully revealed, said Tong Xiaoling with the State Key Laboratory of Silkworm Genome Biology at Southwest University.

Through genome-wide association analysis, the research team found a sugar transporter gene cluster that determines the formation of a green cocoon.

The researchers also analyzed the formation mechanism of cocoon color diversification based on a pan-genome system, and analyzed the evolution of cocoon color from wild to domestic silkworms.

The research is of great practical significance for breeding new silkworm varieties with high quality, and can also provide reference for studying the effects of flavonoids on human health, said Dai Fangyin with Southwest University.