show Abstracthide AbstractYun7Ge (Yun7Ge is represented by Ge in the high-throughput sequencing results) is a giant egg mutant found in the silkworm variety Yun7 (Yun7 is represented by Se in the high-throughput sequencing results). The amount of laid eggs and the hatching rate of Yun7Ge are reduced, which is not conducive to the reproduction. The target gene controlling giant egg trait is located on the Z chromosome (chromosome 1) was determined through genetic analysis. To find mutant gene and explore the relationship between mutant gene and giant egg trait, the differentially expressed genes (DEGs) in the oviducts of Yun7 and Yun7Ge were analyzed by high-throughput sequencing, and two replicates were set for each sample. |log 2|>1, the value of FPKM>100 and the genes were up-regulated or down-regulated in giant eggs of the two replicates as the standard for screening DEGs. A total of 65 DEGs were screened. Among these DEGs, 7 genes were up-regulated and 58 genes were down-regulated in giant eggs. These DEGs were classified according to the chromosome where the genes are located. The results showed that there was only one DEG (PHYHD1) on chromosome Z, and it was almost not expressed in giant eggs. Interestingly, there were 35 DEGs on chromosome 2, including 25 chorion genes, and these 25 genes are all down-regulated. After knocking out the PHYHD1 using CRISPR/Cas9, the chorion genes were significantly down-regulated. These results indicate that the silencing of PHYHD1 leads to the down-regulation of many chorion protein genes, which may be the direct cause of giant eggs. Overall design: To find mutant gene and explore the relationship between mutant gene and giant egg trait, the differentially expressed genes (DEGs) in the oviducts of Yun7 and Yun7Ge were analyzed by high-throughput sequencing, and two replicates were set for each sample.