Transcriptome analysis of Indian freshwater pearl mussel Lamellidens marginalis to unravel the genes associated with biomineralization

Background:The freshwater pearl mussel Lamellidens marginalis is found throughout India and is culturing to produce freshwater pearls. Understanding the process of pearl biomineralization provides insight into the genes responsible for the secretion of the complex nacre. However, information on the transcriptome of L. marginalis pearl sac, mantle tissue and gonads are lacking. Methods and Results: The present study generated the transcriptome resources for L. marginalis and identified genes involved in the biomineralization process in the species. The Illumina paired-end sequencing generated 11.13 million raw reads, and the reads were assembled into 133,246 contigs and 26,373 unigenes. 21,033 out of 26,373 unigenes showed homology with previously reported molluscan proteins. Genes of several proteins associated with biomineralization, namely, pif, perlucin, calreticulin, calmodulin, chitin synthase, chitin dehydrogenase, carbonic anhydrase, tyrosinase, shell matrix protein, chitinase 3, chitinase domain-containing protein 1, chitinase-like protein PB1E7.04c, and putative chitinase-1 were identified in the study. Conclusion: This study's findings will help identify differentially expressed genes that govern the characteristics of the pearl and identify the type-I markers in the genes.