Abstract:The frequent occurrence of summer heatwaves and Pseudomonas plecoglossicida-induced visceral white-nodules disease (VWND) during aquaculture practices have emerged as critical challenges hindering the sustainable development of the small yellow croaker (Larimichthys polyactis) aquaculture. The glutamine fructose-6-phosphate transaminase-1 (gftp1) gene is a critical regulator of signal transduction and stress responses To investigate the response characteristics of gfpt1 gene in L. polyactis to heat stress and P. plecoglossicida infection, this study cloned the coding sequence (CDS) of L. polyactis gfpt1 for the first time. The CDS spans 2,049 bp, encoding a 682-amino acid protein containing the conserved PLN02981 superfamily domain. Homology alignment revealed the highest sequence similarity (99.37%) with L. crocea. Expression analysis revealed that the gfpt1 gene is widely expressed across tissues but exhibits significant tissue-specific expression variation, with the highest expression observed in the liver. Quantitative real-time PCR (qRT-PCR) further demonstrated dynamic transcriptional responses of gfpt1 in L. polyactis liver to heat stress (32°C) and P. plecoglossicida challenge. Under heat stress, gfpt1 expression was significantly upregulated, peaking at 6 h, followed by a gradual decline. In contrast, P. plecoglossicida infection induced a distinct temporal pattern: gfpt1 expression decreased significantly at 6 h post-infection, followed by a significant upregulation peaking at 48 h (P<0.05), which was then followed by a significant downregulation at 96 h (P<0.05). These findings indicate that gfpt1 plays a regulatory role in both heat stress and pathogenic responses, albeit through divergent mechanisms. By integrating molecular cloning and bioinformatics analysis, this study provides pioneering insights into the molecular mechanisms underlying fish responses to environmental stressors and pathogenic invasion. These findings provide critical insights into the physiological regulatory mechanisms underlying fish responses to environmental stressors and pathogen invasion, laying a foundation for advancing aquaculture resilience research.
