Identification and Expression Profiling of Scorpion Ionotropic Receptors and Gustatory Receptors Based on the Transcriptomic Analysis.

Chemical signal perception plays a crucial role in arthropod reproduction and survival. The scorpion is one of the oldest terrestrial arthropods; however, its knowledge of the chemosensory genes remains unclear. Based on the transcriptomic analysis of widely distributed Mesobuthus martensii in China, 46 candidate gustatory receptors (GRs) and 80 candidate ionotropic receptors (IRs)/ionotropic Glutamate receptors (iGluRs) overall showed similar expression trends in different tissues between the third-instar and adult scorpions, which suggested that young scorpions possessed a relatively complete chemical perception capability. Most GRs showed higher transcript accumulation in the pectines, rather than other tissues, aligning with their known chemosensory function and highlighting the remarkable significance of pectines as crucial sensory organs. Conversely, IRs/iGluRs overall exhibited a more widespread distribution throughout the different tissues of the scorpion body. The phylogenetic tree further elucidated the evolutionary relationships among these chemosensory genes in arthropods. These findings contributed to a better understanding of the functionality and evolution of the chemosensory systems in scorpions, which would accelerate the functional investigations of scorpion chemosensory genes in the future.