Enhanced silk yield in transgenic silkworm ( <scp> <i>Bombyx mori</i> </scp> ) via ectopic expression of <scp> <i>BmGT1‐L</i> </scp> in the posterior silk gland
Xin Tang, H. Liu, Z. Shi, Q. Chen, Xiaoli Kang, Yang Wang, Ping Zhao
Abstract
The silkworm is an economically important insect producing plentiful silk fibre in the silk gland. In this study, we reported a cross-talk between the fat body, silk gland and midgut through a glycine-serine biosynthetic pathway in the silkworm. Amino acid sequence and functional domains of glycine transporter gene BmGT1-L were mapped. Our results indicated that BmGT1-L was specifically expressed in the midgut microvilli and persistently expressed during the feeding stages. RNA interference of BmGT1-L activated glycine biosynthesis, and BmGT1-L overexpression facilitated serine biosynthesis in the BmN4-SID1 cell. In addition, silkworms after FibH gene knock-out or silk gland extirpation showed markedly decreased BmGT1-L transcripts in the midgut and disturbed glycine-serine biosynthesis as silk yield decreased. Finally, BmGT1-L ectopic expression in the posterior silk gland promoted glycine biosynthesis, and enhanced silk yield via increasing fibroin synthesis. These results suggested that cross-talk between tissues can be used for enhancing silk yield in the silkworm.