Transcriptomes of silkworm Xuesong KD and Perforated small cocoon whole silkworm at the newly - molted third - instar larvae stage.

The newly identified silkworm mutant, perforated small cocoon (psc), was discovered in the normal silkworm strain XueSong KD (XSKD). During the larval stage, the psc mutant exhibits a smaller body size compared to the wild-type XSKD at the same developmental stage. The cocoons formed by psc are smaller in size and have a reduced whole cocoon weight compared to XSKD. Additionally, the cocoons display small holes at one or both ends, or the cocoon layer at the ends is thinner than other parts. In some cases, the cocoon is even transparent enough to reveal the pupa inside, consistent with the characteristics of "perforated cocoons" (also known as thin-headed or pierced cocoons), hence the name psc.Starting from the third instar feeding stage, the psc mutants showed significantly less weight gain compared to XSKD within the same developmental timeframe. This trend persisted in subsequent stages, though the differences became less pronounced. Genetic analysis revealed that the psc mutation is controlled by a single recessive gene (psc).Transcriptome analysis was performed using whole larvae of psc at the third instar initiation stage, with wild-type XSKD larvae at the same stage serving as the control. Three biological replicates were included for each sample. Using thresholds of |log2(fold change)| > 1 and FPKM > 100 for screening differentially expressed genes (DEGs), 716 DEGs were identified, including 354 upregulated genes and 362 downregulated genes.