Transcriptomic analysis of distinct mantle regions in yellow- and black-shelled Asian clam (Corbicula fluminea): Identification of genes associated with Shell biomineralization and pigment deposition

Corbicula fluminea exhibits two distinct shell color morphs: yellow and black. This study reveals molecular mechanisms behind shell color variation in the Asian clam C. fluminea (yellow vs. black morphs) through comparative transcriptomics of edge/central mantle tissues. Transcriptome assembly identified 24, 174 annotated genes and 2, 234 novel genes. Comparative analyses revealed 238 common differentially expressed genes (DEGs) shared between the YC vs YE and BC vs BE comparisons, along with 575 DEGs in BC vs YC and 460 DEGs in BE vs YE. Transcriptomic profiling demonstrated that Biomineralization genes (calcium/organic matrix-related) showed region-specific expression, driving shell formation. Melanogenesis pathway enrichment and pigmentation genes (tyrosinase, calmodulin, sulfotransferase) may play an important role in pigmentation in C. fluminea. This study expands our understanding of shell biomineralization and pigment deposition in C. fluminea, providing important insights into the genetic and biochemical regulation of shell diversity in bivalves.