Transcriptomic and validation analysis reveal two new bitter taste receptors (T2R) in pigs

Bitter taste perception is important for pig feeding behavior and survival. The family 2 taste receptors (T2R) are a family of G protein-coupled receptors that are responsible for the sense of bitter taste. They are present in taste receptor cells located in the taste buds of the tongue papillae and other parts, for example: the gastrointestinal tract, respiratory epithelia, and more. In this study, we hypothesize that the full T2R gene repertoire in pigs has yet to be uncovered. Based on that, we have used a combination of bioinformatics tools and experimental validation to identify and annotate the T2R transcripts in the pig transcriptome derived from circumvallate papillae (CVP). We have explored the transcriptome of the pig CVP by reference guided assembly to identify potential novel transcripts of T2R genes in 12 pig samples and further confirmed the new protein coding transcripts by PCR and Sanger sequencing. The results confirmed 2 novel T2R transcripts (ENSSSCT00000089410.2, from gene T2R61, and ENSSSCT00000091318.1, from gene T2R62) and additionally, the T2R62 was found to contain larger exons than those annotated in the reference genome. Furthermore, the results resolved that the porcine T2R20 is indeed a member of the porcine T2R family highly similar to multiple human TAS2Rs including TAS2R20 (also referred as TAS2R49). Our research has expanded the knowledge on the porcine T2Rs repertoire and bears potential to inspire further studies on the genetic basis of taste perception, food selection, nutrition, and adaptation biology in pigs.