Characterization of Embryo Transcriptome of Gynogenetic Olive Flounder Paralichthys olivaceus

Olive flounder Paralichthys olivaceus is an important commercially cultured marine flatfish in China, Korea, and Japan. Gynogenesis, via meiogynogenesis and mitogynogenesis, shows advantages in breeding and sex control, but the low survival rate, especially for mitogynogenesis, limits its application. In this study, we sequenced the embryo transcriptomes of gynogenetic haploid, meiogynogenetic diploid, mitogynogenetic diploid, and common diploid flounder and investigated their respective genetic characteristics by analyzing differentiated expressed genes. Compared with common diploid, the gynogenetic haploid showed significant downregulation in notch signaling and wingless-related integration site (Wnt) signaling pathways, which may be the source of haploid syndrome. In both meiogynogenesis and mitogynogenesis, several upregulated genes including complement C3, formin-2, and intelectin may be related to increased survival compared to the haploid. The downregulation of immune system and energy metabolism-related genes caused retarded development of gynogenetic diploids compared with the common diploid. These data provided new and important information for application of artificially induced gynogenesis to aquaculture.