Transcriptome Analysis of Differentially Expressed Genes in Freshwater Pearl Mussel (Sinohyriopsis cumingii) with Four Different Shell Colors

Pearl culture has long been a major global industry. As a significant global producer, China mainly produces pearls from the freshwater mussel (<i>Sinohyriopsis cumingii</i>). <i>S. cumingii</i> with various shell colors can produce pearls of different colors; for example, mussels with a blue-white shell can produce white pearls, while those with a purple shell can produce light-purple pearls. Therefore, investigating the molecular genetics of shell color variation in <i>S. cumingii</i> can advance our understanding of the mechanisms underlying differences in shell and pearl coloration in these mussels. In this study, we selected juvenile <i>S. cumingii</i> with four differently colored inner shells and collected tissue samples for transcriptomic analysis. The results showed that many key genes involved in the regulation of pigment metabolism (such as ADAMTS, TYR, BCDO2, and FTH1), as well as those associated with metabolism and mineral absorption (such as TRPV6, HCP1, HEPH, and Zip4), exhibited significant differences. Furthermore, these DEGs (differentially expressed genes) may influence the synthesis and metabolism of melanin, carotenoids, porphyrins, and heme, thereby affecting shell color variation; they might also be one of the potential reasons why <i>S. cumingii</i> produces pearls of different colors.