Transcriptome-based identification and expression profiling of olfaction-related genes in the semi-aquatic firefly...

The semi-aquatic firefly Pygoluciola qingyu, a bioluminescent insect inhabiting stream and wetland environments, is closely associated with the ecological quality of semi-aquatic habitats and wetland biodiversity. Its unique glow, combined with its ornamental value, also makes it a potential candidate for special aquaculture and ecological landscape enhancement. In this study, transcriptome sequencing of adult antennae and larval heads was performed using the Illumina platform. A total of 35,178 unigenes were obtained, and 8432 differential expression genes were revealed. The assembled unigenes were functionally annotated against the NR, GO, and KEGG databases. Also, 66 olfaction-related genes were identified, including 28 odorant receptors (ORs), 16 gustatory receptors (GRs), 8 ionotropic receptors (IRs), 12 odorant-binding proteins (OBPs), and 2 sensory neuron membrane proteins (SNMPs). OBP relative expression analysis based on RT-qPCR showed that PqinOBPs exhibited differential expression between sexes and among different tissues in adults, with some genes showing relatively higher expression levels in legs. In larval samples, several PqinOBPs displayed significant expression differences between head and body, with generally higher expression in the head. These results clarify the composition and expression profiles of olfaction-related genes in P. qingyu and provide a molecular basis for understanding olfactory perception mechanisms and ecological adaptation in this semi-aquatic firefly.