家蚕基因组为开展家蚕分子育种提供了宝贵的基因资源。然而，如何从上万个候选基因中鉴定出与丝蛋白产量相关的基因却异常困难。基于piggyBac转座子的随机突变体库在果蝇等模式物种基因筛选中得到了成功的应用。在前期研究中，我们应用piggyBac转座子构建了家蚕随机插入突变体库，并从中筛选出了一个“薄茧”突变体。初步鉴定出了4个转座子插入位点，但这些突变基因的功能并没有得到揭示。为此，本课题将继续研究：1）"薄茧“突变体表型性状分析；2）基因组文库Southern杂交，全面鉴定所有转座子插入位点；2）应用RNAi和Crispr/Cas9技术分析突变基因在蚕丝产量形成方面的功能；3）构建转基因家蚕，以提高蚕丝产量。该研究将揭示家蚕“薄茧”突变体形成的分子机制，鉴定出与蚕丝产量相关的功能基因。这不仅有利于解析家蚕蚕丝产量形成的分子机制，还有可能为家蚕育种提供新的靶基因，培育更加高产的家蚕新品种。

The silkworm genome provides important resources for molecular breeding of silkworm. However, it is very hard to identify genes responsible for silk synthesis from the silkworm genome. PiggyBac-based random insertional mutagenesis has been successfully used in model species including Drosophila. In our previous study, a piggyBac-based random insertional mutagenesis library was constructed in Bombyx mori, one mutant with “thin cocoon” was screened, and four insertion sites were identified. However, the functions of these mutant genes have not yet been studied. In this project, researches will be carried out from the following 3 aspects: 1) Phenotype analysis of the “thin cocoon” mutant; 2) Exploring the function of those mutant genes by RNAi and Crispr/Cas9 techniques; 3) Constructing transgenic silkworm to increase silk synthesis. This project will elucidate the molecular mechanisms of “thin cocoon” mutant and identify genes responsible for silk synthesis. It may not only help to understand the mechanism of silk synthesis, but also provide some useful genes for transgenic breeding of silkworm in the future.