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

<h4>Background/objectives</h4>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. <i>T2Rs</i> 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 <i>T2R</i> genes have previously been experimentally identified, although only a limited number of studies have investigated this gene family. We hypothesized that the full <i>T2R</i> gene repertoire in pigs has yet to be uncovered.<h4>Methods</h4>Circumvallate papillae (CVP) were collected from 12 pigs, and a combination of bioinformatics analysis and experimental validation was used to identify and annotate <i>T2R</i> 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.<h4>Results</h4>The results confirmed significant expression of 10 of the 12 known <i>T2Rs (3</i>, <i>4</i>, <i>7</i>, <i>9</i>, <i>10</i>, <i>16</i>, <i>20</i>, <i>39</i>, <i>41</i>, and <i>60</i>). Two novel <i>T2R</i> transcripts (ENSSSCT00000089410.2 and ENSSSCT00000091318.1) were discovered and referred to as <i>T2R61</i> and <i>T2R62</i>. <i>T2R62</i> contained larger exons than those annotated in the reference genome. The results also showed that porcine <i>T2R20</i> is a member of the porcine <i>T2R</i> family highly similar to several human <i>TAS2Rs</i>, including <i>TAS2R20</i> (<i>TAS2R49</i>). In total, the porcine <i>T2R</i> repository contains 14 transcripts supported by strong evidence.<h4>Conclusions</h4>This study expands knowledge of the porcine <i>T2R</i> repertoire and provides insight into the genetic basis of taste perception, food selection, nutrition, and adaptation biology in pigs.