ABSTRACT: Temperature profoundly influences the physiology, survival, and distribution of marine ectotherms, including mollusks. Transient receptor potential (TRP) channels are conserved thermosensory proteins in metazoans, yet their evolutionary diversification and functional roles in gastropod mollusks remain unclear. In this study, we present a comprehensive phylogenetic classification and expression analysis of TRP-like channel genes in Pacific abalone (Haliotis discus hannai). Through the extensive mining of genome and transcriptome datasets, we identified 49 TRP-like genes and categorized them into nine families from two major groups: Group 1 (TRPA, TRPC, TRPM, TRPN, TRPS, TRPV, and TRPVL) and Group 2 (TRPP and TRPML), along with two unclassified TRP-like genes. Phylogenetic analysis incorporating sequences from lophotrochozoans, choanoflagellates, fungi, and green algae outlined a lineage-specific TRP-like gene expansion in mollusks. Spatial expression profiling revealed distinct tissue-specific patterns: TRPC-, TRPM-, and TRPP-like genes were enriched in sensory organs (i.e., the eyes and tentacles), whereas TRPM- and TRPV-like genes were expressed predominantly in respiratory and metabolic tissues (i.e., the gills and hepatopancreas). Under acute thermal stress, RNA sequencing and real-time quantitative PCR identified several thermoresponsive TRP paralogs, including TRPA1- and TRPV-like genes, exhibiting distinct transcriptional regulation. These results elucidate the evolutionary complexity and functional diversification of TRP channels in marine gastropods, and highlight the potential role of these molecules in thermal sensing and adaptation. This study provides a molecular framework for understanding TRP-mediated environmental responses in mollusks, contributing to broader insights into marine invertebrate resilience under climate change.
