Tissue‐Specific Transcriptomic Changes Associated With Mating Status in Overwintering Bombus terrestris Queens

ABSTRACT

Mating status is a key determinant of reproductive physiology in annual bumble bee queens, but its tissue‐specific molecular effects after overwintering remain unclear. We analyzed RNA‐seq data from the brains and ovaries of mated Bombus terrestris queens (BtQ) and unmated (virgin) queens (Bv) using tissue‐wise combined biological replicates ( n  = 2 per mating‐status group). Differentially expressed genes were identified with edgeR, and functional patterns were evaluated by Gene Ontology and KEGG enrichment analyses. Global clustering separated samples primarily by tissue and secondarily by mating status, indicating that tissue identity was the dominant source of transcriptomic variation. In the brain, BtQ‐upregulated genes were enriched for DNA biosynthetic process, DNA polymerase complex, spliceosome, and rRNA‐processing‐related categories, whereas Bv‐upregulated genes were associated with extracellular region, serine‐type endopeptidase inhibitor activity, membrane, transmembrane transport, and oxidoreductase activity. In the ovary, Bv‐upregulated genes were enriched for nucleic acid binding, homologous recombination‐mediated double‐strand break repair, tRNA methylation, germ‐line stem cell division, and transposable element silencing. By contrast, BtQ‐upregulated ovarian genes were enriched for heme binding, DNA biosynthetic process, monooxygenase activity, plasma membrane, oxidoreductase activity, DNA polymerase complex, defense response to bacterium, extracellular region, and iron ion binding, together with additional lipid‐ and metabolism‐related categories. Overall, mating status reshaped overwintering brain and ovary transcriptomes through distinct tissue‐specific programs, with the ovary showing the clearest contrast between a maintenance‐oriented state in unmated queens and a biosynthetic, redox, membrane‐associated, immune, and metabolic state in mated queens.