Genome-wide investigation of the dmrt gene family reveals new insight into the gonad development in Plectropomus leopardus: dmrt2a regulate the development of oocytes

BACKGROUND: Plectropomus leopardus is a hermaphrodite fish with a unique pattern of gonadal development. However, the molecular mechanism of sexual differentiation in this species remains unclear. The Doublesex and Mab-3 related transcription factor (dmrt) gene family are known to play a crucial role in gonad differentiation and development. Notably, systematic investigations into the composition and function of the dmrt gene family in this hermaphrodite fish remain conspicuously lacking. METHODS: In this study, we systematically identified members of the dmrt gene family through genomic database mining in P. leopardus. Tissue and stage-specific expression profiles of dmrt paralogs were quantitatively analyzed using reverse transcription quantitative PCR (qPCR), revealing sexually dimorphic expression patterns in the gonads at various developmental stages. Furthermore, the expression distribution of dmrt2a at different developmental stages was explored using fluorescence in situ hybridization (FISH). Subsequently, dmrt2a was interfered with using RNAi technology, and the regulatory effect of dmrt2a on oocytes was verified by combining FISH and TUNEL assays. RESULTS: In this study, we identified six members of the dmrt gene family in P. leopardus and designated them as dmrt1, dmrt2a, dmrt2b, dmrt3, dmrta1 and dmrta2 based on the homology analysis results, respectively. Whole-tissue expression analysis revealed that the dmrt genes exhibit tissue-specific expression pattern in P. leopardus. Notably, dmrt1 and dmrt2a are highly expressed in the gonads, suggesting their potential role in gonadal development. Further qPCR results showed that dmrt genes are differentially expressed between males and females at different developmental stages. Among them, dmrt2a is highly expressed in the ovary at different developmental stages and is found to be a pivotal factor in ovarian development. FISH was used to further verify the expression of dmrt2a in oocytes. In addition, knockdown of dmrt2a in gonads caused oocyte apoptosis and decreased oocyte number, demonstrating the critical role of dmrt2a in oocyte development. CONCLUSIONS: This study demonstrates that dmrt2a plays a crucial regulatory role in the development of the oocytes in P. leopardus, supplementing the understanding of the functional roles of the dmrt gene family in vertebrate sex differentiation. These findings will help to understand the properties and functions of the dmrt genes in P. leopardus and provide a solid basis for further studies on the functional mechanisms of dmrt genes in hermaphroditic fish.