Comparative transcriptome analysis of hybrid Jinhu grouper (Epinephelus fuscoguttatus ♀ x Epinephelus tukula ♂) and Epinephelus fuscoguttatus under temperature stress

The Jinhu grouper, a hybrid of tiger grouper (Epinephelus fuscoguttatus female) and potato grouper (E. tukula male), is a new germplasm with excellent characters. To understand the molecular mechanism underlying the responses of Jinhu grouper and tiger grouper to temperature stress, we performed comparative transcriptome analyses of liver, muscle, and brain tissues at three temperatures (18 C-degrees, 24 C-degrees, and 30 C-degrees). In total, 28,331 genes and 4380 differentially expressed genes among temperature treatments were obtained using the Illumina NovaSeq 6000 platform. GO and KEGG enrichment analyses indicated that binding, catalytic activity, metabolic process, carbon metabolism, complement and coagulation cascade, AMPK signaling pathway, FoxO signaling pathway, and ECM-receptor interaction may be involved in temperature adaptation in tiger grouper and Jinhu grouper. We also found differences in the expression of several PPAR signaling pathway-related genes (such as acsl1, slc27a2, and ppard) in tiger grouper and Jinhu grouper, and HSP genes (hsp30, hsp70, hsp90aa1, hsp90b1, hspa5, hspa4, hspa8, hspa9, and hspa13) were highly expressed in the brain tissue of Jinhu grouper. It is speculated that Jinhu grouper has better temperature tolerance than tiger grouper. In addition, a weighted gene co-expression network analysis was used to identify target modules (i.e., EF.greenyellow, EF.sienna3, EF.brown, EFET.salmon, EFET.red, and EFET.pink) significantly associated with temperature stress in the liver, muscle, and brain tissues of tiger grouper and Jinhu grouper, and a series of hub genes were detected in the network diagrams of these six target modules. These results deepen our understanding of the complex molecular mechanisms underlying the response to temperature stress in tiger grouper and Jinhu grouper.