Identification of the differentially expressed genes of Pinctada maxima individuals with different sizes through transcriptome analysis

The oyster species Pinctada maxima is cultured for the production of large pearls with high economic value. Pearl weight and thickness are related to the growth of P. maxima. The molecular mechanism underlying the growth of this species, however, remains poorly understood given the limited availability of the genetic and genomic information of this species. Here, the molecular mechanism of the asynchronous growth of P. maxima was investigated. The transcriptomes of large and small P. maxima individuals were sequenced using the Illumina HiSeq 2000 platform. A total of 145,877 unigenes were generated for the transcriptomes, and 1,921 differentially expressed genes (DEGs) were identified. Compared with the slow-growing group, the fast-growing group showed 879 and 1,042 significantly up- and down-regulated DEGs, respectively. The differential expression patterns of nine selected genes were obtained through real-time quantitative polymerase chain reaction analysis and showed consistency with those obtained through RNA-Seq analysis. The results of this study provide further insight on the complexity of the differential growth patterns of P. maxima individuals and will help guide the design of breeding programs for this economically important species.