Single-Cell Deconvolution Reveals Phenotype-Associated Cellular States in the Silk Glands of Bombyx mori and Its Wild Ancestor

Silk production is a classic example of a domestication trait, yet the cell-type-specific driver of its enhancement in the silkworm <i>Bombyx mori</i> remains unresolved. To address this, we integrated extensive bulk RNA-seq data with a single-nucleus RNA-seq atlas of silk glands (SGs) from domestic <i>B. mori</i> and wild <i>B. mandarina</i> for deconvolution analysis. This identified phenotype-associated cell subpopulations (Scissor+ and Scissor- cells) that enrich in <i>B. mori</i> and <i>B. mandarina</i>, respectively. Transcriptomic characterization revealed that <i>B. mori</i> SG cells exhibit a pervasive "pro-synthesis" transcriptional state, with concerted upregulation of silk protein genes and metabolic pathways. Conversely, <i>B. mandarina</i> cells maintained a "protective-adaptive" state, enriched for stress response and xenobiotic metabolism genes. Pseudotime analysis further delineated the cell state transitions, pinpointing key dynamic gene expression linked to high silk yield. Our findings demonstrate that domestication reshaped the silk gland cellular landscape, promoting a systemic shift toward a synthesis-optimized cell state. This study offers a new framework at the cellular level to elucidate the evolution of complex traits under selection.