The Bitter Taste Receptor (T2R) Gene Repertoire in the Porcine Circumvallate Papillae Consists of Fourteen Genes, Including Two Newly Validated T2R61 and T2R62

Background/Objectives: Bitter taste perception is important for pig feeding behavior and survival. The type 2 taste receptors (T2Rs) are G protein-coupled receptors responsible for the sense of bitter taste perception in mammals. T2Rs are expressed in taste receptor cells located in the taste buds of the papillae of the tongue and in other tissues such as the gastrointestinal tract, respiratory epithelia, and immune system. In pigs, twelve T2R genes have previously been experimentally identified, although only a limited number of studies have investigated this gene family. We hypothesized that the full T2R gene repertoire in pigs has yet to be uncovered. Methods: Circumvallate papillae (CVP) were collected from 12 pigs, and a combination of bioinformatics analysis and experimental validation was used to identify and annotate T2R transcripts in the pig transcriptome. The CVP transcriptome was explored using reference-guided assembly to identify potential novel transcripts, and newly identified protein-coding transcripts were confirmed by PCR and Sanger sequencing. Results: The results confirmed significant expression of 10 of the 12 known T2Rs (3, 4, 7, 9, 10, 16, 20, 39, 41, and 60). Two novel T2R transcripts (ENSSSCT00000089410.2 and ENSSSCT00000091318.1) were discovered and referred to as T2R61 and T2R62. T2R62 contained larger exons than those annotated in the reference genome. The results also showed that porcine T2R20 is a member of the porcine T2R family highly similar to several human TAS2Rs, including TAS2R20 (TAS2R49). In total, the porcine T2R repository contains 14 transcripts supported by strong evidence. Conclusions: This study expands knowledge of the porcine T2R repertoire and provides insight into the genetic basis of taste perception, food selection, nutrition, and adaptation biology in pigs.