Physiological response and transcriptomics study of three Litopenaeus vannamei populations to alkaline stress and...

The development of alkali-tolerant shrimp strains is crucial for sustainable aquaculture in saline-alkaline waters. However, the population-specific genetic basis of alkali tolerance remains poorly understood. This study investigated the immuno-physiological and transcriptomic responses of three Litopenaeus vannamei populations (DF, XH and SIS) to alkaline stress (AG, 15 mmol/L alkalinity for 72 h), and recovery (AR, post-stress return to 1.2 mmol/L for 72 h). Alkaline stress induced significant gill and hepatopancreas damage, characterized by structural distortion and vacuolization. Physiologically, stress suppressed antioxidant capacity (SOD, CAT, GSH-Px) and elevated lipid peroxidation (MDA), while simultaneously activating immune defenses (increased ACP and ALP activities) and disturbing osmoregulation (altered NKA and CA activities). During recovery, tissue integrity and antioxidant capacity improved, and immune/osmoregulatory indicators partially recovered, though not fully to control levels. Transcriptomic analysis revealed population-specific response strategies: The XH (4932 and 4435 DEGs during stress and recovery, respectively) maintains homeostasis via synergistic activation of oxidative phosphorylation and glutathione metabolism across both stages to mitigate oxidative stress; The DF (13,047 and 2579 DEGs) activates innate immunity through pathways like C-type lectin receptor signaling under stress and relied on arachidonic acid metabolism-involved metabolic adaptation during recovery; The SIS population (11,842 and 3351 DEGs) potentially undergoes insulin-PI3K-Akt-mTOR-driven immunometabolic reprogramming under alkaline stress, and may mediate epithelial barrier repair via, for example, the Rap1 signaling pathway and other related pathways during the recovery phase. WGCNA identified 23 hub genes (e.g., APOD, ARSB, RPS15/19/5, SORD) that coordinate stress adaptation by immune responses, oxidative damage alleviation, and regulating energy metabolism. This study reveals dynamic changes in gene expression profiles and regulatory networks of different L. vannamei populations during acute alkaline stress and short-term recovery, providing key theoretical basis for elucidating their alkali tolerance molecular mechanisms.