An amino acid-tuned gustatory receptor relatively abundant in the silkworm gut is crucial for growth and development

BACKGROUND

Gustatory organs are distributed throughout the insect body, including mouthpart, tarsi, and gut. The highly differentiated gustatory receptors (GRs) expressed in these organs are used to perceive diverse phytochemicals, enabling the identification of feeding stimulants or deterrents essential to maintain necessary life activities. The silkworm, a representative Lepidoptera species, has been a classic model for studying the gustation of phytophagous insects. Previous studies have revealed that GRs expressed in silkworm mouthpart are involved in host-plant recognition. However, the gustation mechanism in the silkworm internal tissues is not well understood.

RESULTS

In this study, the gustatory receptor BmGr29, which is relatively highly expressed in the silkworm gut and has seven transmembrane domains, was identified. RNA in situ hybridization showed that this receptor was enriched in the silkworm midgut. Compared with wild-type (WT) individuals, the food intake, weight gain of larvae and the size, weight of pupa were significantly reduced in BmGr29-knock out (KO) mutants. Through autodocking and voltage clamp, it was found that BmGr29 was specifically tuned to two amino acids, proline and asparagine.

CONCLUSION

This study comprehensively analyzed the function of BmGr29 highly expressed in gut, a silkworm internal organ. The tuning between GRs and amino acids expanded our understanding about insect adaptations to plants, and provided perspectives to further research about feeding regulation mechanisms. © 2025 Society of Chemical Industry.