Transcriptome-based analysis reveals relationship between duck eggshell color and eggshell strength.

BACKGROUND: The strength of duck eggshells is essential for their storage, transportation, and processing, with various studies indicating a correlation between eggshell color and strength. RESULTS: Our research has demonstrated that green-shelled duck eggs exhibit higher eggshell strength compared to white-shelled eggs in the M2 Line Pekin Duck population. To this end, we established mRNA transcriptome profiles of 10 eggshell gland tissues and 10 liver tissues and constructed gene expression networks in the two tissues. RNA-Seq analysis suggests that genes associated with ion transport, transmembrane transport, and liver cell proliferation and differentiation in the eggshell gland could play important roles in eggshell formation. The liver of green shell duck has stronger cell proliferation ability to maintain its homeostasis, and the eggshell gland has stronger ability to secrete eggshell matrix protein, which may be the reason why the eggshell is stronger than that of white shell duck. Through Weighted gene co-expression network analysis (WGCNA), three related modules were found in eggshell gland and liver, respectively, and three key genes were screened in each tissue (eggshell gland: FKBP10, PPARG, MAP3K5, liver: PHLDA1, FLT3, CACNB4). They have important regulatory effects on eggshell color and eggshell strength respectively. CONCLUSIONS: Through transcriptome analysis, we identified key genes associated with eggshell color (ESB) (Gland: ABCG2, SLC51B; Liver: COX1, DIO3, RBPJ) and eggshell strength (ESS) (Gland: MAP3K5, PPARG, FKBP10; Liver: PHLDA1, FLT3, CACNB4). We propose that these genes regulate ESB and ESS by modulating antioxidant capacity and bile acid synthesis in the liver and shell gland, leading to enhanced biliverdin deposition and stronger eggshells in green-shelled ducks. Additionally, the upregulation of ion transport, transmembrane transport, and liver cell proliferation-related genes in green-shelled ducks further supports the observed superiority in eggshell strength.