Transcriptomic insights into hydrostatic-pressure-induced triploidy in large yellow croaker (Larimichthys crocea) across developmental stages

Induced triploidy is used in aquaculture to generate functionally sterile stocks and may alter the allocation of resources among growth, maintenance, and reproduction. However, the molecular responses associated with hydrostatic-pressure induction and triploidy remain poorly characterized in large yellow croaker ( Larimichthys crocea ). In this study, fertilized eggs assigned to the induction group were exposed to 7000 PSI hydrostatic pressure for 3 min at 2 min 30 s post-fertilization. Ploidy analysis confirmed triploid status in the pressure-induced groups and diploid status in the controls. RNA sequencing was performed on whole-body samples from 5-day-old larvae and dorsal fin tissue from 8-month-old fish, with three biological replicates for each treatment group and sampling context. A total of 1,194 differentially expressed genes (DEGs) were detected in larvae, including 859 upregulated and 335 downregulated genes in triploids, whereas 3,174 DEGs were identified in 8-month-old fish, including 1,497 upregulated and 1,677 downregulated genes. Larval DEGs were enriched in cell-cell adhesion, epithelial polarity, tight junction, protein digestion and absorption, and innate immune-related pathways. The larval protein-protein interaction network highlighted claudin-family genes and digestive proteases, with most hub genes showing higher expression in triploids, although CLDN15 and CLDN18 displayed the opposite pattern. In 8-month-old fish, DEGs were dominated by ribosome biogenesis, rRNA processing, spliceosome, RNA degradation, mitochondrial translation, glutathione metabolism, and amino acid and steroid metabolism. Hub genes involved in ribonucleoprotein assembly and mitochondrial ribosomes were consistently lower in triploid dorsal fin. These findings reveal stage- and tissue-context-dependent transcriptomic responses to triploidy and identify candidate molecular modules for subsequent validation of epithelial, translational, metabolic, and immune phenotypes in triploid large yellow croaker.