Integrated Transcriptomic and Metabolomic Analyses Reveal the Adaptive Mechanisms of a Low-Salinity Selected Population of Pacific White Shrimp (Litopenaeus vannamei)

Litopenaeus vannamei is one of the most widely farmed shrimp species worldwide, but it traditionally exhibits limited adaptability to low-salinity environments. Genetic improvement through intraspecific hybridization has been proven effective in enhancing environmental adaptability. This study aimed to elucidate the molecular mechanisms underlying the low-salinity adaptation of a hybrid shrimp strain selected through intraspecific hybridization. Shrimp were reared for 12 weeks under salinity conditions of 1 practical salinity unit (PSU) and 15 practical salinity units (PSU). By conducting a combined analysis of transcriptomics and metabolomics, we explored the low-salt adaptation mechanism of the hybrid shrimp. We found that they enhanced their adaptability through self-osmotic regulation and energy regulation. Transcriptome results revealed that genes associated with calcium-activated chloride channels, chloride transporters, and sodium-driven chloride/bicarbonate exchangers were up-regulated, suggesting enhanced ion transport capacity under low salinity. The metabolomics results indicated that key enzymes involved in glycolysis and gluconeogenesis, including phosphofructokinase and phosphoenolpyruvate carboxykinase, showed increased abundance, indicating elevated energy metabolism to support osmotic adjustment. Overall, the selected hybrid shrimp enhanced osmotic regulation by strengthening energy metabolism to improve their low-salt adaptability. These findings provide valuable insights for future genetic breeding and sustainable shrimp aquaculture in low-salinity regions.